Assessment on Use of Spectrum in the 10-17 Ghz Band for the GSO Fixed-Satellite Service in Region 1

Report ITU-R S.2365-0 (09/2015)

Assessment on use of spectrum in the 10-17 GHz band for the GSO fixed-satellite service in Region 1

S Series Fixed satellite service

ii Rep. ITU-R S.2365-0

Foreword

The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and economical use of the radio- frequency spectrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the basis of which Recommendations are adopted. The regulatory and policy functions of the Radiocommunication Sector are performed by World and Regional Radiocommunication Conferences and Radiocommunication Assemblies supported by Study Groups.

Policy on Intellectual Property Right (IPR)

ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Annex 1 of Resolution ITU-R 1. Forms to be used for the submission of patent statements and licensing declarations by patent holders are available from http://www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation of the Common Patent Policy for ITU-T/ITU-R/ISO/IEC and the ITU-R patent information database can also be found.

Series of ITU-R Reports (Also available online at http://www.itu.int/publ/R-REP/en)

Series Title BO Satellite delivery BR Recording for production, archival and play-out; film for television BS Broadcasting service (sound) BT Broadcasting service (television) F Fixed service M Mobile, radiodetermination, amateur and related satellite services P Radiowave propagation RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space applications and meteorology SF Frequency sharing and coordination between fixed-satellite and fixed service systems SM Spectrum management

Note: This ITU-R Report was approved in English by the Study Group under the procedure detailed in Resolution ITU-R 1.

REPORT ITU-R S.2365-0

Assessment on use of spectrum in the 10-17 GHz band for the GSO fixed-satellite service in Region 1 (2015)

TABLE OF CONTENTS Page

1 Introduction ...... 3

2 Overview of current unplanned FSS allocations in Region 1 ...... 3

3 Assessment of spectrum in the 10-17 GHz band for unplanned FSS ...... 4 3.1 Possible bands for consideration ...... 4

4 General FSS characteristics ...... 5 4.1 VSAT transmission type ...... 6 4.2 Wideband transmission type ...... 6 4.3 Point-to-Point transmission type ...... 6 4.4 FSS characteristics for single entry analysis ...... 6 4.5 FSS (Earth-to-space) characteristics for cumulative analysis ...... 8 4.6 GSO FSS satellite locations and distributions ...... 9 4.7 FSS earth station deployment density ...... 9

5 Frequency band 10.0-10.5 GHz ...... 11 5.1 Review of Recommendations ...... 12 5.2 Sharing studies for the band 10-10.5 GHz ...... 12 5.3 Summary of studies for the band 10.0-10.5 GHz ...... 18

6 Frequency band 10.5-10.6 GHz ...... 18 6.1 Review of Recommendations and Reports ...... 18 6.2 Sharing studies for the band 10.5-10.6 GHz ...... 19 6.3 Summary of studies for the band 10.5-10.6 GHz ...... 19

7 Frequency band 10.6-10.68 GHz ...... 20 7.1 Review of Recommendations ...... 21 7.2 Sharing studies for the band 10.6-10.68 GHz ...... 21 7.3 Summary of studies for the band 10.6-10.68 GHz ...... 36

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Page

8 Frequency band 13.25-13.4 GHz ...... 37 8.1 Review of Recommendations/Reports ...... 37 8.2 Sharing studies for the band 13.25-13.4 GHz ...... 38 8.3 Summary of studies for the band 13.25-13.4 GHz ...... 145

9 Frequency band 13.4-13.75 GHz ...... 147 9.1 Review of Recommendations/Reports ...... 147 9.2 Sharing studies for the band 13.4-13.75 GHz ...... 148 9.3 Summary of studies for the band 13.4-13.75 GHz ...... 199

10 Frequency band 14.5-14.8 GHz ...... 199 10.1 Review of Recommendations ...... 199 10.3 Summary compatibility of studies between FSS (Earth-to-space) and existing services in the band 14.5-14.8 GHz ...... 343

11 Frequency band 14.8-15.35 GHz ...... 347 11.1 Review of Recommendations for the band of 14.8-15.35 GHz ...... 348 11.2 Sharing studies for the band 14.8-15.35 GHz ...... 348 11.3 Summary of studies for the band 14.8-15.35 GHz ...... 366

12 Frequency band 15.35-15.4 GHz ...... 367

13 Frequency bands 15.4-15.43 GHz, 15.43-15.63 GHz and 15.63-15.7 GHz ...... 367 13.1 Review of Recommendations and Reports ...... 368 13.2 Sharing studies for the band 15.4-15.7 GHz ...... 368 13.3 Summary of studies for the band 15.4-15.7 GHz ...... 394

14 Frequency band 15.7-16.6 GHz ...... 395 14.1 Review of Recommendations/Reports ...... 395 14.2 Sharing studies for the band 15.7-16.6 GHz ...... 396 14.3 Summary of studies for the band 15.7-16.6 GHz ...... 401

15 Frequency band 16.6-17.0 GHz ...... 401 15.1 Review of Recommendations/Reports ...... 402 15.2 Sharing studies for the band 16.6-17.0 GHz ...... 402 15.3 Summary of studies for the band 16.6-17 GHz ...... 403

Annex ...... 404 Rep. ITU-R S.2365-0 3

Reference documents [1] Recommendation ITU-R P.525-2 – Calculation of free-space attenuation [2] Recommendation ITU-R P.528-3 – Propagation curves for aeronautical mobile and radionavigation services using the VHF, UHF and SHF bands [3] Recommendation ITU-R S.465-6 – Reference radiation pattern for earth station antennas in the fixed- satellite service for use in coordination and interference assessment in the frequency range from 2 to 31 GHz [4] Report ITU-R S.2364-0 – GSO FSS deployment characteristics in the 14-14.5 GHz band [5] Report ITU-R S.2196-0 – Methodology on the modelling of earth station antenna gain in the region of the antenna main-lobe and the transition region between the minimum angle of the reference antenna pattern and the main-lobe [6] Recommendation ITU-R M.2068-0 – Characteristics of and protection criteria for systems operating in the mobile service in the frequency range 14.5-15.35 GHz

1 Introduction The existing unplanned fixed-satellite service (FSS) bands are extensively used for a myriad of applications. The very small aperture terminal (VSAT) services, video distribution, broadband networks, internet services, satellite news gathering, and backhaul links have triggered the rapid rise in the demand. Satellite traffic is typically symmetrical in a large variety of applications, i.e. similar amounts of Earth-to-space (uplink) and space-to-Earth (downlink) traffic are transmitted. WRC-12 adopted two new Resolutions (Resolutions 151 (WRC-12) and 152 (WRC-12)) to study, as a matter of urgency, possible primary allocations for unplanned FSS to address the asymmetry in Regions 2 and 3 as well as look for additional Earth-to-space and space-to-Earth operations for the unplanned FSS in Region 1. It should be noted that a world-wide allocation for FSS has a significant advantage over a regional one. For example, equal FSS allocation for Regions 1 and 3 is typical and important in terms of planning and construction of satellite networks, as well as achieving effective coverage area. Having spectrum on a harmonized basis across the world facilitates economies of scale and provides the needed flexibility to support mobility applications where VSAT terminals operate on platforms moving across oceans and continents. Also, in terms of improving spectral efficiency and convenience of communications set up (system architecture), it is desirable that an additional spectrum for FSS be allocated in a continuous part of the spectrum that is contiguous to the existing FSS allocations. This Report provides an assessment for additional primary allocations for FSS spectrum for Region 1 as instructed by Resolution 151 (WRC-12).

2 Overview of current unplanned FSS allocations in Region 1 In Region 1 there are equal allocations between uplink and downlink spectrum, however there is a difference of 250 MHz and 300 MHz of unplanned FSS spectrum when compared with Regions 2 and 3, respectively, as shown in Table 2-1.

4 Rep. ITU-R S.2365-0

TABLE 2-1 The current unplanned FSS bands in the 10-15 GHz range in Region 1 Frequency bands Bandwidth (GHz) (MHz) Earth-to-space direction (uplink) 13.75-14.5 750 Total spectrum in the uplink 750 space-to-Earth direction (downlink) 10.95-11.2 250 11.45-11.7 250 12.5-12.75 250 Total spectrum in the downlink 750 Region 2 spectrum in the downlink 1000 Region 3 spectrum in the downlink 1050 Spectrum difference from other ITU Regions 250/300

3 Assessment of spectrum in the 10-17 GHz band for unplanned FSS Resolution 151 (WRC-12) provides for study of frequency bands in the 10-17 GHz range for their suitability in addressing the shortage in the uplink and downlink spectrum in Region 1 when compared with the rest of the world’s FSS allocations. Therefore, this Report provides a compilation of those studies in order to identify suitable frequency bands which could resolve this issue, while ensuring compatibility with the existing services in identified bands and allocations.

3.1 Possible bands for consideration The bands considered in this Report are 10-17 GHz in Region 1 for FSS Earth-to-space and space-to- Earth operations. Additional unplanned FSS spectrum in the Earth-to-space and space-to-Earth directions that is contiguous (or near contiguous) to the existing allocations is most appropriate to address this uplink/downlink spectrum insufficiency for the following reasons: – it would help to ensure compatibility with the existing ground infrastructure; – the necessity to invest in new user equipment would be minimized; – the design of the satellite could be simplified and this reduces the cost of the satellite project. These above measures effectively translate to a reduction in costs to the end users. Table 3-1 shows the frequency arrangement used to separate the sharing studies into manageable segments. Rep. ITU-R S.2365-0 5

TABLE 3-1 Summary of possible bands for additional FSS uplink/downlink bands

Frequency bands Bandwidth Current Allocation to FSS (GHz) (MHz) 10.0-10.45 450 No 10.45-10.5 50 No 10.5-10.55 50 No 10.55-10.6 50 No 10.6-10.68 80 No 13.25-13.4 150 No 13.4-13.75 350 No 14.5-14.8 300 Yes, uplink but limited to feeder links for the broadcasting-satellite service outside Europe. (RR No. 5.510), and per Resolution 152 resolves 2, “...appropriate measures need to be taken with regard to the Appendix 30A Plan and List ...” 14.8-15.35 550 No 15.35-15.4 50 No** 15.4-15.43 30 No* 15.43-15.63 200 Yes, but limited to feeder links of non-geostationary systems in the mobile-satellite service (RR No. 5.511A) 15.63-15.7 70 No* 15.7-16.6 900 No 16.6-17.0 400 No * Allocated to FSS for which complete information for advance publication has been received by the BR by 21 November 1997. ** Footnote RR No. 5.340 applies.

4 General FSS characteristics This section provides information on the FSS characteristics that should be used in sharing studies. The FSS characteristics as provided in Table 4-1, should be used to generate results based on the potential interference from one FSS earth station while the FSS characteristics as provided in Tables 4-2, should be used to generate results based on cumulative interference (static and dynamic analysis) from all FSS earth stations and space stations. The model contained herein defines three main types of transmissions (VSAT, Wideband, and Point- to-Point) currently active on fixed satellite systems and the relative frequency of use of these transmission types. For each of the transmission types, typical earth station characteristics are outlined. The characteristics in the tables below are taken from a statistical analysis of all the transmissions from 73 active satellites in 14.0-14.5 GHz band. There was an overall total of 25,937 transmissions which gives an average of 355 transmissions per satellite. The use of transmission types serves to provide an accurate description of FSS earth station operations and their transmissions.

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4.1 VSAT transmission type Very small aperture terminals (VSATs) are earth stations with small diameter antennas that commonly transmit carriers with lower e.i.r.p. densities and smaller bandwidths. Transmissions by VSATs are typically return links carrying data from remote sites back to a hub station or links between VSAT terminals. The VSAT transmission type constitutes about 69.3% of uplink FSS transmissions, which represents 15.28% of the total bandwidth. Transmissions were considered to be of the VSAT transmission type if the transmitting earth station was less than 3 m in diameter and the bandwidth was less than 3 MHz. A total of 17,982 transmissions met the criteria of the VSAT transmission type and the statistical analysis of their characteristics is provided in later sections.

4.2 Wideband transmission type Wideband transmissions are typically data or video carriers from hub stations. These stations transmit wideband carriers have large diameters and the ability to transmit higher e.i.r.p. densities. In addition to the hub station transmissions, earth stations used for SNG can also transmit wideband carriers. Although the SNGs have small diameters, some have high gains and can transmit higher e.i.r.p. densities. The Wideband transmission type constitutes about 4.9% of uplink FSS transmissions, which represents 56.8% of the total bandwidth. Any transmission in the sample with a bandwidth of 18 MHz or larger was classified as belonging to the Wideband transmission type. The 18 MHz limit was used because it is half of a typical transponder bandwidth. In order for the satellite to receive transmissions with large bandwidths, a higher e.i.r.p. must be transmitted. Earth stations with higher gains, including the high-gain SNG terminals, are required to achieve this higher e.i.r.p. A total of 1,258 transmissions met the criteria of the Wideband transmission type and the statistical analysis of their characteristics is provided in later sections.

4.3 Point-to-Point transmission type Point-to-Point transmissions include all other transmissions that are not classified as belonging to the VSAT or Wideband transmission types. The earth stations transmitting Point-to-Point links typically have diameters and e.i.r.p. densities larger than VSATs but smaller than hub stations transmitting Wideband carriers. The Point-to-Point transmission type constitutes about 25.8% of uplink FSS transmissions, which represents 27.92% of the total bandwidth. In the analysis, all transmissions that did not meet the criteria of the VSAT or Wideband transmission types were classified as Point-to-Point links. Transmissions from earth stations in this transmission type have bandwidths less than 18 MHz and varying antenna diameters. A total of 6,697 transmissions met the criteria of the Point-to-Point transmission type and the statistical analysis of their characteristics is provided in later sections.

4.4 FSS characteristics for single entry analysis Table 4-1 contains some maximal characteristics for the FSS in the 10-17 GHz band. The impact of each transmission type should be evaluated individually. Table 4-1 includes a sampling of transmitting earth station antenna patterns and characteristics for use in FSS networks. Recommendations ITU-R S.1855 and ITU-R S.728 are used for the off-axis antenna pattern or off- axis e.i.r.p. density mask as appropriate. Recommendation ITU-R BO.1213 is considered primarily for modelling the main lobe characteristics of an FSS earth station antenna. The maximum power spectral density (PSD) values for the future FSS allocation can be expected to range between ‒60 and ‒47 dBW/Hz depending on the application envisaged. For the VSAT Rep. ITU-R S.2365-0 7 transmission type, the application generally requires a PSD of around –50 dBW/Hz. In some cases, this could be exceeded (e.g. ‒42 dBW/Hz). For the Wideband and Point-to-Point transmission types, the PSD values are typically lower but could go as high as –50 dBW/Hz. The FSS GSO satellite downlink characteristics in the 10-17 GHz band are considered to have the maximum allowable pfd at the Earth’s surface for the frequency band under consideration as specified by RR No. 21.16. This pfd level was designed to protect terrestrial systems that share existing FSS frequencies on a co-primary basis. Typically, FSS GSO satellite downlink transmissions have e.i.r.p. density levels usually between –35 and –20 dBW/Hz depending on the transmission requirements, which are significantly lower than the –13 dBW/Hz level that would be derived from RR No. 21.16.

TABLE 4-1 Single Entry characteristics for the FSS in the 10-17 GHz band

Satellite Downlink e.i.r.p. spectral density –20 (dBW/Hz) Transmissions per satellite1 355 Earth station Transmission type VSAT Wideband Point-to-Point Percentage of total satellite transmissions 69.3 4.9 25.8 Range of peak antenna gains2 (dBi) 37.2 – 50.5 51.7 – 60.8 43.9 – 57.2 Range of antenna sizes (m) 0.6 ‒ 2.8 3.2 – 9.1 1.3 – 6.0 3 dB beamwidth at 14 GHz3 (°) 1.15 0.85 0.74 Maximum power spectral density at –424 –49 –505 antenna port (dBW/Hz) Alternative maximum power spectral –59 –55 –50 –60 –57 –53 –60 –57 –53 density at antenna port (dBW/Hz)6 Maximum e.i.r.p. density at the transmit 1.5 3.0 3.5 antenna port (dBW/Hz)7 Minimum elevation angle 10° Off-axis radiation pattern S.1855 S.580 S.580 Off-axis power limits Rec. ITU-R S.7288 Main lobe characteristics Rec. ITU-R BO.1213

8 Rep. ITU-R S.2365-0

Notes to Table 4-1: 1 Accounts for current frequency reuse involving spot beams. Current frequency reuse is on the order of 1.2. 2 The peak antenna gain is estimated at the centre of the band (14.25 GHz) and 65% efficiency. 3 The 3dB beamwidth was calculated assuming non-uniform illumination using 70° as the coefficient relating the ratio λ/D to the beamwidth (θ3dB=70λ/D). 4 This level is derived based on Recommendation ITU-R S.728 and is 8 dB higher than one known administration’s domestic rules for routine licensing of VSAT earth stations. Currently, there are a small number of ESs operating at this power level. 5 This level is equivalent to one known administration’s domestic rules for routine licensing of FSS earth stations. 7 The maximum e.i.r.p. density at the antenna port is the actual maximum e.i.r.p. seen in operation. It corresponds to gains values of 43.5 dBi (1.2 m), 52 dBi (3.3 m), and 53.5 dBi (3.9 m) for VSAT, Wideband, and Point-to-Point respectively, transmitting the maximum PSD quoted in the table. 8 Recommendation ITU-R S.728-1 ‒ Maximum permissible level of off-axis e.i.r.p. density from very small aperture terminals (VSATs)

4.5 FSS (Earth-to-space) characteristics for cumulative analysis Table 4-2 provides the antenna diameter sizes to be considered as well as the average bandwidths, the percentages of the total transponder bandwidth consumed by the global deployment, and mean of peak envelope power density of the particular ES diameter. The standard deviations of PSD and e.i.r.p. density can be derived from the cumulative data graphs provided in Report ITU-R S.2364 [4]. The total transponder bandwidth of the system operator was examined to determine how much of the total bandwidth was used by a certain transmission type. These numbers were provided by two FSS providers as being representative for their global networks.

TABLE 4-2 Typical characteristics for the FSS (Earth-to-space) in the 10-17 GHz band

Transmission Type VSAT Wideband Point-to-Point Number of Transmissions in the FSS 17 982 1 258 6 697 Model1 Average Bandwidth of Transmission 0.58 30.84 2.94 (MHz) Total Spectrum Usage 10 440 38 801 19 072 (MHz) Percentage of Spectrum Usage (%) 15.28 56.80 27.92 Mean of peak PSD@ antenna envelope power –54.19 –56.43 –57.52 port (dBW/Hz) density

e.i.r.p. Density Mean of peak envelope power –9.23 –3.40 –5.62 (dBW/Hz) density Rep. ITU-R S.2365-0 9

TABLE 4-2 (end)

Transmission Type VSAT Wideband Point-to-Point Average 0.6 30.8 2.9 Bandwidth Standard (MHz) 0.8 6.5 3.5 Deviation Average 1.73 6.13 3.62 Antenna size (m) Standard 0.37 0.98 0.79 Deviation 1 500 MHz, dual polarization.

4.6 GSO FSS satellite locations and distributions For the purpose of this study, 120 FSS satellites could be assumed at 3° spacing even if in some portions of the orbital arc less than or greater than 3° spacing is employed.

4.7 FSS earth station deployment density In addition, if a frequency band is used by an earth station employing a continuous carrier in a specific beam towards a specific space station, no other earth stations could use simultaneously this frequency in this specific beam towards this specific space station. Therefore, in order to have two earth stations operating, in the same area, the same frequency simultaneously, we need to have two space stations and so on. Depending on the parameters of the transmit earth stations, we could assume to have a space station every 2-4° on the GSO arc with a minimum elevation angle of 10-20°. With such assumptions, Europe could only be potentially served from space stations of around 30 different geostationary orbital locations. According to current surfaces on the majority of beams from space stations covering Europe, the average beam coverage surface is around 10 000 000 km2. Therefore, considering around 30 maximum earth stations operating simultaneously in Europe on the same frequency and same polarization at the same time on the same beam, the current density over Europe is around 3E-6 transmit (3-degree compliant) earth stations per km2. This number can increase when dual polarization is taken into account and also depends on the victim receiver bandwidth considered.

4.7.1 Frequency reuse factor The use of spot beams on FSS GSO satellites could increase the effective amount of available amount of total global bandwidth at a geostationary orbital location. This effective increase of available spectrum is dependent upon sufficient isolation between beams. For instance, if there is a geographical overlap between two spot beams of the same frequency of one or more satellites in an orbital slot then a earth station to that orbital slot, at that same frequency, operating in the area of the geographical overlap would be seen by both spot beams and thereby reduce the amount of overall available bandwidth (for uplink and downlink transmission) by the bandwidth carrier of this earth station operating in that geographical overlap. With sufficient isolation between spot beams originating from a geostationary orbital location, two spot beams would double the available amount of total global bandwidth if all spectrum is implemented on-board the aircraft in each beam. However, it should be recognized that, in practice, the use of multiple beams using the same frequencies in the 14.00-14.50 GHz is currently not universal and the current frequency reuse, of about 1.1 per satellite, introduced by the use of spot beams and dual polarization has been accounted for in the transmission

10 Rep. ITU-R S.2365-0 data presented. However, this frequency reuse factor may not be representative of an FSS deployment based on future satellites, with multiple spot beams and increased frequency reuse and the frequency reuse factor should be re-evaluated as information on future satellite technologies and capacities becomes available.

4.7.2 Possible evolution of the Frequency reuse factor To assess the Frequency reuse factor (FRF) trend expected in the future, a survey was made using the launch date of the satellites considered in the study providing an overall Frequency reuse factor of 1.1. As shown in the graph below, the overall FRF is slightly increasing by around 4% every 5 years during the last 14 years. Using a linear extrapolation of the same trend into the future, the FRF could be predicted to be equal to 1.4 in around 20 years, to 1.6 in around 40 years, to 2 in around 70 years and to 5 during the 23rd century. Therefore, considering the trend observed on the evolution of the FRF during these last decades and the stability period of an ITU environment, it had been proposed to consider a maximum FRF of 1.5 in the studies performed under this report in order to assess the potential future impact of a possible FSS allocation.

FIGURE 4-1 Frequency reuse factor trend observed the last decades

It is to be noted that the usage and deployment of multi spot beams technology with implementation of all or part of the same frequency band in each spot beam will increase the overall capacity of satellite communication systems. Technical reports claim that the advent of high-throughput satellites (HTS) enables network service providers to offer a new generation of communications solutions. Rep. ITU-R S.2365-0 11

Each spot beam uses the same frequencies so that a single HTS spacecraft could provide five to ten times the capacity of traditional satellites. This new type of satellite is mainly envisaged in Ka bands as utilization of narrow spot beams is required to increase satellite capacity as well as compensate the important degradation of the signal due to the rain. As the rain degradation is limited in C and Ku bands compare to Ka band, most of the new satellites are expected to have large regional beams which limit the number of possible additional beams using simultaneously the same frequency bands due to sufficient required isolation between beams. Nevertheless some HTS satellites are envisaged in C and Ku bands with four to five times more capacity than traditional satellites. Another point to consider is that although the frequency reuse factor is partially dependent on the capacity and capabilities of a single FSS satellite, the frequency reuse factor is completely dependent on the total capacity and capabilities of the aggregate FSS satellites at a GSO orbital location. It is important to note that multiple FSS GSO satellites are currently co-located and occupy the same orbital slot in the 14-14.5 GHz band. Most of the time, these co-located satellites are used as backup in case of satellite failure to not disrupt the service, customers are transferred to a backup satellite on the same frequency and same coverage. The advent of high-throughput satellites (HTS) enables network service providers to offer a new generation of communications solutions. Depending on the configuration of the service areas and innovative ground and space technologies, future communication systems will be probably capable of maximizing the available frequency for transmissions. In an HTS, each spot beam uses the same frequencies in multiple carriers enabling a single HTS spacecraft to provide five to ten times the capacity of traditional satellites at Ku (14.0-14.5 GHz) band. It appears that a future frequency reuse factor for each GSO location of 5 is reasonable to assume for future HTS on a per orbital slot basis. The frequency reuse factor of 1.5 was calculated per FSS satellite basis. Therefore, assuming that in the future half of the GSO satellites may use HTS technologies, the overall frequency reuse factor would become 2.5. For the purpose of compatibility analysis under agenda item 1.6, the range for frequency reuse factor per satellite orbital slot would range from 1.5 (1.7 dB) to 2.5 (4 dB).

5 Frequency band 10.0-10.5 GHz The allocations of this band in RR Article 5 are shown below.

TABLE 5-1 Excerpts from Article 5 of the Radio Regulations on allocation to services in 10.0-10.5 GHz Allocation to services Region 1 Region 2 Region 3 10-10.45 10-10.45 10-10.45 FIXED RADIOLOCATION FIXED MOBILE Amateur MOBILE RADIOLOCATION RADIOLOCATION Amateur Amateur 5.479 5.479 5.480 5.479 10.45-10.5 RADIOLOCATION Amateur Amateur-satellite 5.481

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5.479 The band 9 975-10 025 MHz is also allocated to the meteorological-satellite service on a secondary basis for use by weather radars. 5.481 Additional allocation: in Germany, Angola, Brazil, China, Costa Rica, Côte d'Ivoire, El Salvador, Ecuador, Spain, Guatemala, Hungary, Japan, Kenya, Morocco, Nigeria, Oman, Uzbekistan, Paraguay, Peru, the Dem. People’s Rep. of Korea, Romania, Tanzania, Thailand and Uruguay, the band 10.45-10.5 GHz is also allocated to the fixed and mobile services on a primary basis. (WRC-07)

5.1 Review of Recommendations A list of relevant Recommendations that may be useful for sharing studies is summarized in Table 5-2.

TABLE 5-2 Summary of relevant Recommendations that may be useful for sharing studies in the band 10-10.5 GHz Service Relevant Recommendation Fixed Recommendation ITU-R F.699 Recommendation ITU-R F.758 Recommendation ITU-R F.1107 Recommendation ITU-R F.1245 Recommendation ITU-R F.1333 Recommendation ITU-R F.1336 Recommendation ITU-R F.1777 Recommendation ITU-R F.747 Recommendation ITU-R F.1568 Mobile Recommendation ITU-R M.1824 Radiolocation Recommendation ITU-R M.1796

5.2 Sharing studies for the band 10-10.5 GHz 5.2.1 FSS (s-E) and FS According to RR Article 5, FS is allocated on a primary basis in frequency band 10.0-10.45 GHz in Regions 1 and 3, and also has additional primary allocation in some countries in frequency band 10.45-10.5 GHz according to RR No. 5.481.

5.2.1.1 Technical characteristics and typical parameters of FS stations Table 5-3 provides technical characteristics and typical parameters of digital point-to-multipoint (PMP) FS systems in frequency band 10.0-10.68 GHz in accordance with Recommendation ITU-R F.758. Permissible long-term aggregate interference level Iag for terrestrial FS stations from GSO-FSS satellites is determined by criteria Iag/N = −10 dB, where N – receiver noise power density typical of FS station under Recommendation ITU-R F.758. Rep. ITU-R S.2365-0 13

TABLE 5-3 Technical characteristics and typical parameters of digital FS systems in frequency band 10.0-10.68 GHz FS system PMP FS system Parameter (1) (2) Frequency band (GHz) 10.15-10.68 Reference ITU-R Recommendation F.747, F.1568 Central Terminal Station Modulation Stations 64-QAM 64-QAM Channel spacing and receiver noise bandwidth (MHz) 1.75; 2.5; 5; 1.75; 2.5; 5; 28; 28; 30 30 Tx output power range (dBW) −3 −12 Tx output power density range (dBW/MHz) −5.43 −14.4 Feeder/multiplexer loss range (dB) 0.5 0 Antenna type and gain range (dBi) 15 18 (microstrip (panel) sectoral) (1) 2.32 Dant /  3.27 e.i.r.p. range (dBW) 11.5 6 e.i.r.p. density range (dBW/MHz) 9.07 3.57 Receiver noise figure typical (dB) 5 5

Receiver noise power density typical (=NRX) −139 −139 (dBW/MHz) Normalized Rx input level for 1 × 10−6 BER −112.5 −112.5 (dBW/MHz) Nominal long-term interference power density −149 −149 (dBW/MHz) (1) Ratio Dant /  is estimated for given maximum antenna gain value in accordance with Recommendation ITU-R F.699.

In calculations for terminal stations the antenna pattern according to Recommendation ITU-R F.1245 was used. In calculations for central stations omni-directional antenna in the azimuth plane and antenna pattern according Recommendation ITU-R F.1336 for vertical plane were used. Information about antenna elevation angles of FS stations that were used during calculations is based on BR IFIC data. According to BR IFIC No. 2737 data (Terrestrial services) from 05.02.2013 there are 9 798 records of terrestrial FS stations in frequency band 10.0-10.68 GHz in Region 1 and information about the antenna elevation angle is indicated for 9 528 stations. Weight coefficient W e0 for FS receiver stations with different antenna elevation angle values is provided in Table 5-4.

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TABLE 5-4 Distribution of FS stations under antenna elevation angle value in frequency band 10.0-10.68 GHz in Region 1

FS antenna elevation Number of FS stations Weight coefficient angle recorded in the MIFR for W  (degree) Region 1 e0 Frequency band 10.0-10.68 GHz 3…25.5 74 0.0078 2…3 49 0.0051 1…2 54 0.0057 –1 … +1 9 176 0.9631 –24.5… –1 175 0.0184

Considering that the typical elevation of the central station antenna of P-MP systems is in the range from 0 to ‒3 degrees, in calculations for this type of stations were used weighting coefficients shown in Table 5-5.

TABLE 5-5 Distribution of FS central stations of P-MP systems under antenna elevation angle value in frequency band 10.0-10.68 GHz

FS antenna elevation Number of FS stations Weight coefficient angle recorded in the MIFR for (degree) Region 1 Frequency band 10.0-10.68 GHz ‒1…0 8952 0.9647 ‒2…‒1 192 0.0207 ‒2…‒3 98 0.0106 ‒24.5 … ‒3 38 0.0041

5.2.1.2 Compatibility studies 5.2.1.2.1 Calculation results of probability of causing harmful interference to FS terrestrial stations The calculation of average probability Р of interference criterion exceeding of FS stations was done under methodology that is accurately described in Document 4А/317 (2007-2012 study period) that provides estimation of probability of causing harmful interference to FS terrestrial stations from geostationary BSS satellites in the frequency band 21.4-22.0 GHz. This document was considered and approved under study for WRC-12 agenda item 1.13. The following input parameters are used for estimation of probability Р in present case: – latitude φ of FS terrestrial stations allocation varies from 0° to 74° with step 2°; – antenna elevation angle e of FS terminal station takes values 0° (for FS antenna elevation angles from –1° to +1°), 2° (for FS antenna elevation angles from 1° to 2°), 3°( for FS antenna Rep. ITU-R S.2365-0 15

elevation angles from 2° to 3°), 5° (for FS antenna elevation angles from 3°). Interference from satellites visible at the elevation angle less than minus 1° was not taken into account for FS terminal stations; – antenna beam azimuth angles of FS terrestrial station changing within the range from 0° to 360° with step 0.2°; – interference from 4 nearest satellites was taken into account, assuming all satellites positions at GSO are equiprobable and equally separated with angle γ = 3º or 10º (satellite separation); – avoidance angle from the point of exact direction to GSO  = ±1.5° (RR Article 21, Table 21-1); – minimum propagation attenuation due to atmospheric gases is calculated according to Recommendation ITU-R SF.1395 (assuming h = 0.1 km) for frequency band 10.7-11.7 GHz (which is the closest to 10.0-10.68 GHz). The effect of signal refraction in atmosphere was not considered. Rain attenuation was not taken into account. Calculation results of probability of permissible interference criterion exceeding for FS terrestrial stations was fulfilled for two cases: – without assumption of FS station antenna beam avoidance from exact pointing on GSO; – in assumption that FS station antenna beams should avoid an exact GSO direction for not less, than ε = 1.5º (similarly to Table 21-1 of RR Article 21). All other azimuth A values are equiprobable except for two prohibited sections χ(ε,φ), where ε = ±1.5º. The calculation results of probability of causing harmful interference to FS PMP systems from GSO-FSS (space-to-Earth) in frequency band 10.0-10.68 GHz are provided in Tables 5-6 and 5-7 for different FSS (space-to-Earth) e.i.r.p. spectral density values.

TABLE 5-6 Probability of interference criterion exceeding for FSS (space-to-Earth) spectral density e.i.r.p. 40 dBW/MHz, %(NRX(1) = 141 dBW/MHz; NRX(2) = 140 dBW/MHz; NRX(3),(4) = 139 dBW/MHz)

FS system type and PMP FS system antenna gain GSO-FSS (1) (2) satellite separation 15 18 Condition (dBi) (dBi) 3 without initial avoidance 98.891% 8.045% 3 with avoidance 1.5° 96.46% 6.790% 10 without initial avoidance 98.8912% 7.156% 10 with avoidance 1.5° 96.46% 5.791%

16 Rep. ITU-R S.2365-0

TABLE 5-7 Probability of interference criterion exceeding for FSS (space-to-Earth) spectral density e.i.r.p. 34 dBW/MHz, % (NRX(1) = 141 dBW/MHz; NRX(2) = 140 dBW/MHz; NRX(3),(4) = 139 dBW/MHz)

FS system type and PMP FS system antenna gain GSO-FSS (1) (2) satellite separation 15 18 Condition (dBi) (dBi) 3 without initial avoidance 0% 1.102% 3 with avoidance 1.5° 0% 0.488% 10 without initial avoidance 0% 8.309·10-3% 10 with avoidance 1.5° 0% 4.02·10-3%

5.2.1.3 Summary When GSO-FSS (space-to-Earth) spectral density e.i.r.p. is 40 dBW/MHz towards the horizon or with elevation angle lower than 10°, the probability of long-term aggregate interference criterion exceeding Iag/N = −10 dB for stations of PMP FS systems in frequency band 10.15-10.68 GHz varies: – from 7.156% to 98.981% without the FS station antenna beam avoidance from an exact GSO direction; – from 5.791% to 96.46% with FS station antenna beam initial avoidance from an exact GSO direction for angle not less than 1.5°. When GSO-FSS (space-to-Earth) spectral density e.i.r.p. is 34 dBW/MHz towards the horizon or with elevation angle lower than 10°, the probability of long-term aggregate interference criterion exceeding Iag/N = −10 dB for stations of PMP FS systems in frequency band 10.15-10.68 GHz varies: – from 0% to 1.102% without the FS station antenna beam avoidance from an exact GSO direction; – from 0% to 0.488% with FS station antenna beam initial avoidance from an exact GSO direction for angle not less than 1.5°. 34 dBW/MHz corresponds to a pfd value of –128 dBW/m2 per 1 MHz, which is only 2 dB lower than the RR Article 21 Table 21-4 limits for GSO FSS (space-to-Earth) in the frequency band 10.7-11.7 GHz. It is necessary to take into consideration that the given estimation is overestimated as the majority of FS stations operate with margin of signal to noise ratio and also because in calculation were not considered interfering signal rain attenuation and its correlation with wanted signal attenuation on FS link. However it should be taken into account that fixed stations possible additional SNR margin cannot be assured and in particular the fade margin of fixed station link is assigned for particular performance requirements and is not designed for interference mitigation. It is also necessary to take into account that the majority of GSO-FSS not radiate their maximal spectral density e.i.r.p. towards the horizon or with low elevation due to the power limitation onboard the satellite. Therefore, compatibility conditions between FSS (space-to-Earth) and FS stations are possible based on following pfd limits into FSS space stations. Rep. ITU-R S.2365-0 17

− –128 dBW/m2 per 1 MHz for angles of arrival from 0 to 5 degrees; − –128+0.6(δ-5) dBW/m2 per 1 MHz for angles of arrival from 5 to 25 degrees; − –116 dBW/m2 per 1 MHz for angles of arrival from 25 to 90 degrees. 5.2.2 FSS (s-E) and MS No sharing studies were submitted to the ITU-R for FSS (s-E) satellite systems and mobile systems in the band 10.0-10.5 GHz.

5.2.3 FSS (s-E) and RLS No sharing studies were submitted to the ITU-R for FSS (s-E) satellite systems and radiolocation systems in the band 10.0-10.5 GHz.

5.2.4 FSS (s-E) and RAS operating in adjacent frequency band The protection criteria for the stations of the radio astronomy continuum observations in the frequency band 10.60-10.68 GHz is a pfd of –180 dBW/m2 in 1 MHz (Table 1 of Annex 1 to Recommendation ITU-R RA.769). The threshold pfd level for protection of the stations of the radio astronomy for VLBI observations is –133 dBW/m2 per MHz (Table 3 of Annex 1 to Recommendation ITU-R RA.769). Table 5-8 contains the calculation results of the adjacent band interference from a FSS satellite to the stations of the radio astronomy service (Continuum and VLBI). TABLE 5-8 FSS e.i.r.p. (dBW/MHz) 40 Adjacent band power ratio (dB) 35* e.i.r.p. in adjacent band (dBW/MHz) 5 Minimum spreading factor 162.1 Maximun pfd at earth surface (adjacent band) (dBW/m2 in 1 MHz) –157.1 Continuum Assumed bandwidth (MHz) 100 Threshold pfd in assumed bandwidth (dBW/m2) –160 Threshold pfd in 1 MHz (dBW/m2) –180 Threshold excess (dB) 22.9 VLBI Reference bandwidth (Hz) 1 Threshold pfd in assumed bandwidth (dBW/m2) –193 Threshold pfd in 1 MHz (dBW/m2) –133 Threshold excess (dB) –24.1 * Typical characteristic of out-of-band emission suppression.

The calculation results showed that additional attenuation of out-of-band emissions is required to ensure compatibility of the radio astronomy service (Continuum). Based on the assumption that attenuation of the main emissions of FSS satellite in the adjacent band is 35 dB additional filtering of the out-of-band emissions by 23 dB in the radio astronomy band is required. In order to protect RAS it is required 58 dB limitation of the out-of-band emissions of FSS satellite in the radio astronomy band.

18 Rep. ITU-R S.2365-0

It is important to note that bands 10.7-10.95 GHz, adjacent to the RAS band. is currently allocated to FSS and operating satellites are designed in a way to fully protect the RAS band. Therefore, it is not expected difficulty to share with RAS considering a minimum frequency separation of 100 MHz with a possible new FSS allocation in the band 10-10.5 GHz.

5.3 Summary of studies for the band 10.0-10.5 GHz No sharing studies were submitted to the ITU-R for FSS (s-E) satellite systems and mobile systems in the band 10.0-10.5 GHz. No sharing studies were submitted to the ITU-R for FSS (s-E) satellite systems and radiolocation systems in the band 10.0-10.5 GHz.

6 Frequency band 10.5-10.6 GHz The allocations of these bands in RR Article 5 are as shown below.

TABLE 6-1 Excerpts from Article 5 of the Radio Regulations on allocation to services in 10.5-10.6 GHz Allocation to services Region 1 Region 2 Region 3 10.5-10.55 10.5-10.55 FIXED FIXED MOBILE MOBILE Radiolocation RADIOLOCATION 10.55-10.6 FIXED MOBILE except aeronautical mobile Radiolocation

6.1 Review of Recommendations and Reports A list of relevant Recommendations and Reports that may be useful for sharing studies is summarized in Table 6-2.

TABLE 6-2 Summary of relevant Recommendations that may be useful for sharing studies in the band 10.5-10.6 GHz

Service Relevant Recommendation Relevant Reports Fixed Recommendation ITU-R F.699 Recommendation ITU-R F.758 Recommendation ITU-R F.1107 Recommendation ITU-R F.1245 Recommendation ITU-R F.1333 Recommendation ITU-R F.1336 Recommendation ITU-R F.1777 Recommendation ITU-R F.747 Recommendation ITU-R F.1568 Mobile Recommendation ITU-R M.1824 Rep. ITU-R S.2365-0 19

TABLE 6-2 (end)

Service Relevant Recommendation Relevant Reports Radiolocation Recommendation ITU-R M.1796 Report ITU-R М.2221 Recommendation ITU-RM.1461 Radioastronomy Recommendation ITU-R RA.769 Report ITU-R М.2221 Recommendation ITU-R RA.1031-2 Recommendation ITU-R RA.1513-1

The frequency band 10.5-10.6 GHz was considered previously in the studies carried out under WRC-12 agenda item 1.25. These studies addressed the sharing feasibility of the mobile satellite service (MSS) (space-to-Earth) with the existing services. The studies showed that the sharing with the radiolocation service (RLS) and also with radioastronomy service (RAS) operating in the adjacent frequency band (10.6-10.7 GHz) is quite complicated. The study results are given in Report ITU-R М.2221 and also in the CPM Report to WRC-12.

6.2 Sharing studies for the band 10.5-10.6 GHz 6.2.1 FSS (s-E) and FS See § 5.2.1.

6.2.2 FSS (s-E) and MS No sharing studies were submitted to the ITU-R for FSS (s-E) satellite systems and mobile systems in the band 10.5-10.6 GHz.

6.2.3 FSS (s-E) and RLS The characteristics of RLS stations operating in the frequency band 10.5-10.6 GHz are given in Recommendation ITU-R M.1796. The issue of providing protection for G16, G17, G18 and G19 stations given in the indicated Recommendation is addressed in Report ITU-R М.2221. The pfd level of –146 dBW/m2 per 1 MHz is required for RLS station protection. Taking that into account in accordance with RR Article 21 Table 21.4 for GSO FSS (space-to-Earth) the following pfd limitations are applied in the frequency band 10.7-11.7 GHz: − –126 dBW/m2 per 1 MHz for angles of arrival from 0 to 5 degrees; − –126+0.5(δ-5) dBW/m2 per 1 MHz for angles of arrival from 5 to 25 degrees; − –116 dBW/m2 per 1 MHz for angles of arrival from 25 to 90 degrees. 6.2.4 FSS (s-E) and radio astronomy service operating in the adjacent frequency band The studies as contained in the section concerning the sharing between FSS (space-to-Earth) and RAS in the band of 10.0-10.5 GHz are applicable to the 10.5-10.6 GHz band.

6.3 Summary of studies for the band 10.5-10.6 GHz No sharing studies were submitted to the ITU-R for FSS (s-E) satellite systems and mobile systems in the band 10.5-10.6 GHz. In order to protect the existing RLS systems in the band 105.10.6 GHz, a pfd level of –146 dBW/m2 per 1 MHz is required for FSS (s-E) systems.

20 Rep. ITU-R S.2365-0

7 Frequency band 10.6-10.68 GHz The allocations of these bands in RR Article 5 are as shown below.

TABLE 7-1 Excerpts from Article 5 of the Radio Regulations on allocation to services in 10.6-10.68 GHz Allocation to services Region 1 Region 2 Region 3 10.6-10.68 EARTH EXPLORATION-SATELLITE (passive) FIXED MOBILE except aeronautical mobile RADIO ASTRONOMY SPACE RESEARCH (passive) Radiolocation 5.149 5.482 5.482A

5.149 In making assignments to stations of other services to which the bands:

13 360-13 410 kHz, 4 950-4 990 MHz, 102-109.5 GHz, 25 550-25 670 kHz, 4 990-5 000 MHz, 111.8-114.25 GHz, 37.5-38.25 MHz, 6 650-6 675.2 MHz, 128.33-128.59 GHz, 73-74.6 MHz in Regions 1 and 3, 10.6-10.68 GHz, 129.23-129.49 GHz, 150.05-153 MHz in Region 1, 14.47-14.5 GHz, 130-134 GHz, 322-328.6 MHz, 22.01-22.21 GHz, 136-148.5 GHz, 406.1-410 MHz, 22.21-22.5 GHz, 151.5-158.5 GHz, 608-614 MHz in Regions 1 and 3, 22.81-22.86 GHz, 168.59-168.93 GHz, 1 330-1 400 MHz, 23.07-23.12 GHz, 171.11-171.45 GHz, 1 610.6-1 613.8 MHz, 31.2-31.3 GHz, 172.31-172.65 GHz, 1 660-1 670 MHz, 31.5-31.8 GHz in Regions 1 and 3, 173.52-173.85 GHz, 1 718.8-1 722.2 MHz, 36.43-36.5 GHz, 195.75-196.15 GHz, 2 655-2 690 MHz, 42.5-43.5 GHz, 209-226 GHz, 3 260-3 267 MHz, 48.94-49.04 GHz, 241-250 GHz, 3 332-3 339 MHz, 76-86 GHz, 252-275 GHz 3 345.8-3 352.5 MHz, 92-94 GHz, 4 825-4 835 MHz, 94.1-100 GHz, are allocated, administrations are urged to take all practicable steps to protect the radio astronomy service from harmful interference. Emissions from spaceborne or airborne stations can be particularly serious sources of interference to the radio astronomy service (see Nos. 4.5 and 4.6 and Article 29). (WRC-07) 5.482 In the band 10.6-10.68 GHz, the power delivered to the antenna of stations of the fixed and mobile, except aeronautical mobile, services shall not exceed –3 dBW. This limit may be exceeded, subject to agreement obtained under No. 9.21. However, in Algeria, Saudi Arabia, Armenia, Azerbaijan, Bahrain, Bangladesh, Belarus, Egypt, United Arab Emirates, Georgia, India, Indonesia, Iran (Islamic Republic of), Iraq, Jordan, Libyan Arab Jamahiriya, Kazakhstan, Kuwait, Lebanon, Morocco, Mauritania, Moldova, Nigeria, Oman, Uzbekistan, Pakistan, Philippines, Qatar, Syrian Arab Republic, Kyrgyzstan, Singapore, Tajikistan, Tunisia, Turkmenistan and Viet Nam, this restriction on the fixed and mobile, except aeronautical mobile, service is not applicable. (WRC-07) Rep. ITU-R S.2365-0 21

5.482A For sharing of the band 10.6-10.68 GHz between the Earth exploration-satellite (passive) service and the fixed and mobile, except aeronautical mobile, services, Resolution 751 (WRC-07) applies. (WRC-07)

7.1 Review of Recommendations A list of relevant Recommendations that may be useful for sharing studies is summarized in Table 7-2.

TABLE 7-2 Summary of relevant Recommendations that may be useful for sharing studies in the band 10.6-10.68 GHz Service Relevant Recommendation Earth exploration-satellite Recommendation ITU-R RS.515 (passive) Recommendation ITU-R RS.1803 Recommendation ITU-R RS.1861 Recommendation ITU-R RS.2017 Fixed Recommendation ITU-R F.699 Recommendation ITU-R F.758 Recommendation ITU-R F.1107 Recommendation ITU-R F.1245 Recommendation ITU-R F.1333 Recommendation ITU-R F.1336 Recommendation ITU-R F.1777 Recommendation ITU-R F.747 Recommendation ITU-R F.1568 Mobile Recommendation ITU-R M.1824 Radiolocation Recommendation ITU-R M.1796 Space research (passive) Recommendation ITU-R RS.2064 Radioastronomy Recommendation ITU-R RA.769 Recommendation ITU-R RA.1031-2 Recommendation ITU-R RA.1513-1

7.2 Sharing studies for the band 10.6-10.68 GHz 7.2.1 FSS and EESS (passive) 7.2.1.1 EESS (passive) characteristics A similar calculation has been performed at the last WRC-12 study cycle concerning agenda item 1.25 (MSS bands between 4 and 16 GHz): for this Agenda item, the band 10.6-10.7 GHz was examined in order for potential MSS operating below 10.6 GHz not to cause excessive out-of-band emission within the passive band 10.6-10.7 GHz. The band 10.6-10.68 GHz is allocated to the Earth exploration-satellite service (EESS passive), radio astronomy and space research (passive) services and also terrestrial services (fixed and mobile). The band 10.6-10.7 GHz is of primary interest to measure rain, snow, sea state, and ocean wind. The band 10.68-10.7 GHz has a provision, RR No. 5.340, relevant for passive services.

22 Rep. ITU-R S.2365-0

At WRC-07, RR No. 5.482A was added, which introduces the limits applicable for the fixed and mobile services in order to protect the EESS (passive) for the band 10.6-10.68 GHz (Resolution 751 (WRC-07) applies). In view of the limits in Resolution 751 (WRC-07), the band 10.6-10.68 GHz should not be considered for FSS uplink operations. The following two Recommendations establish the interference criteria for passive sensors: 1) Recommendation ITU-R RS.515-5 ‒ Frequency bands and bandwidths used for satellite passive services 2) Recommendation ITU-R RS.2017 ‒ Performance and interference criteria for satellite passive remote sensing The technical characteristics of the EESS (passive) systems in frequency band 10.6-10.68 GHz are presented in: 1) Recommendation ITU-R RS.1803 ‒ Technical and operational characteristics for passive sensors in the EESS (passive) to facilitate sharing of the 10.6-10,68 GHz and 36-37 GHz bands with the fixed and mobile services. 2) Recommendation ITU-R RS.1861 ‒ Typical technical and operational characteristics of EESS (passive) systems using allocation between 1.4 and 275 GHz. The first criterion is the acceptable interference power received by the EESS sensor which is −166 dBW in the reference bandwidth of 100 MHz. This is a maximum interference level from all sources. The second criterion is the frequency of occurrence limit on the threshold being exceeded. These interference levels should not be exceeded for more than 0.1% of sensor viewing area (data availability of 99.9%) for measurement area defined as a square on the Earth of 10 000 000 km2. The compatibility analyses with EESS (passive) are based on technical characteristics derived from Recommendation ITU-R RS.1861: the Table hereunder shows specifications for five microwave radiometric systems.

TABLE 7-3 EESS (passive) sensor characteristics in the 10.6-10.7 GHz band

Sensor C1 Sensor C2 Sensor C3 Sensor C4 Sensor C5 Sensor type Conical scan Orbit parameters Altitude 817 km 705 km 833 km 835 km 699.6 km Inclination 98° 98.2° 98.7° 98.85° 98.186° Eccentricity 0 0.0015 0 0 0.002 Repeat period N/A 16 days 17 days N/A 16 days Sensor antenna parameters Number of beams 1 2 1 Reflector diameter 0.9 m 1.6 m 2.2 m 0.6 m 2.0 m Maximum beam gain 36 dBi 42.3 dBi 45 dBi 36 dBi 44.1 dBi Polarization H, V H, V, R, L H, V −3 dB beamwidth 2.66° 1.4° 1.02° 3.28 1.2° Rep. ITU-R S.2365-0 23

TABLE 7-3 (end)

Sensor C1 Sensor C2 Sensor C3 Sensor C4 Sensor C5 Sensor antenna parameters Instantaneous field of 56 km × 51 km × 48 km × 76 km × 41 km × view 30 km 29 km 28 km 177 km 21 km Main beam efficiency 94.8% 95% 93% Off-nadir pointing 47.5° 44.3° 47.5° 47° 55.4° angle 2.88 s scan Beam dynamics 20 rpm 40 rpm 31.6 rpm 40 rpm period Incidence angle at 55° 52° 55° 58.16° 65° Earth –3 dB beam 56.7 km 27.5 km 42.9 km N/A 23 km dimensions (cross-track) (cross-track) (cross-track) (cross-track) Swath width 1 594 km 1 450 km 1 600 km 2 000 km 1 450 km See Rec. Sensor antenna pattern ITU-R Fig. 8a Fig. 8b See Rec. ITU-R RS.1813 RS.1813 Cold calibration ant. N/A 29.1 dBi N/A 29.6 dBi gain Cold calibration angle (degrees re. satellite N/A 115.5º N/A 115.5º track) Cold calibration angle (degrees re. nadir N/A 97.0º N/A 97.0º direction) Sensor receiver parameters Sensor integration time 1 ms 2.5 ms 2.47 ms N/A 2.5 ms Channel bandwidth 100 MHz 100 MHz centred at 10.65 GHz Measurement spatial resolution Horizontal resolution 38 km 27 km 15 km 38 km 23 km Vertical resolution 38 km 47 km 15 km 38 km 41 km

24 Rep. ITU-R S.2365-0

FIGURE 7-1 Sensor C1 antenna pattern envelope for the 10.6-10.7 GHz band

FIGURE 7-2 Sensor C2 antenna pattern envelope for the 10.6-10.7 GHz band

7.2.1.2 FSS (space-to-Earth) and (Earth-to-space) characteristics See § 4. Rep. ITU-R S.2365-0 25

7.2.1.3 Compatibility analysis 7.2.1.3.1 FSS (space-to-Earth) into EESS (passive) 7.2.1.3.1.1 Study #1 For the purpose of this study, according to RR No. 21.16, Table 21-4, the power flux-density at the Earth’s surface produced by FSS emission equals –140 dBW/m2 per 4 kHz for the band 10.7-11.7 GHz (for angles of arrivals above the horizontal plane from 25 degrees to 90 degrees) as assumption. It is proposed that this value is adopted for this compatibility analysis. This value would correspond to a GSO FSS e.i.r.p. of 46.10 dBW/MHz. Two geometric situations are examined: – the first situation is when the EESS (passive) sensor receives all the FSS downlink energy through the backlobe.

AMSR-E CMIS SENSOR- EESS (passive) sensor SENSOR-5 SENSOR-2 SENSOR-3 1 Forward link e.i.r.p. (dBW/MHz) 46.10 46.10 46.10 46.10 Distance GSO FSS – Satellite EESS passive (km) 35 084.00 35 079.00 34 951.00 34 967.00 Space attenuation (dB) 203.85 203.85 203.82 203.82 Backlobe sensor satellite antenna gain (dBi) –17.00 –17.00 –17.00 –15.00 Received power at the EESS sensor (dBW/MHz) –174.75 –174.75 –174.72 –172.72 Margin (dB) –11.25 –11.25 –11.28 –13.28

– the second situation is when the EESS (passive) sensor receives downlink FSS backscattered energy (a backscatter coefficient of 10% has been used).

EESS (passive) sensor AMSR-E SENSOR-2 Reflected area (km2) 2.00E+03 FSS ground pfd (dBWm2/4 kHz) –140.00 Backscatter coeff (%) 10.00 Power reflected in 100 MHz (1 MHz) –33.01 Distance ground – Satellite EESS passive (km) 1 124.00 Space attenuation (dB) 173.96 Passive sensor satellite antenna gain (dBi) 42.30 Received power at the EESS sensor (dBW/MHz) –164.67 Negative margin (dB) –21.33

The margins are all negative in both configurations, from –11 down to –21 dB.

7.2.1.3.1.2 Study #2 This study examines the potential of the proposed FSS space-to-Earth allocation for interference to EESS (passive) sensors in the 10.6-10.7 GHz band. The 10.6-10.7 GHz band is currently allocated for EESS (passive). The proposed FSS allocation overlaps with the EESS (passive) allocations, which creates a potential for interference from FSS into space-borne EESS (passive) sensors.

26 Rep. ITU-R S.2365-0

The potential for interference is of great concern due to the high sensitivity of EESS (passive) sensors. Figure 7-3 shows the potential interference scenarios (in dotted lines) to EESS (passive) sensors that will be discussed in this Report.

FIGURE 7-3 Interference scenarios from proposed FSS allocations to EESS (passive) sensors

FSS satellite EESS spacecraft

FSS to EESS Interference

FSS (ES)

7.2.1.3.1.2.1 FSS interference to EESS (passive) 10.6-10.7 GHz band Recommendation ITU-R RS.2017 establishes protection criterion of –166 dBW/100 MHz for the EESS (passive) receivers in the 10.6-10.7 GHz band. Interference analysis was performed to determine whether the interference from proposed FSS satellite into EESS (passive) receivers exceed the protection criterion. In accordance with Recommendation ITU-R RS.1861, Table 7-3 of this report shows specifications for five microwave radiometric systems. As an example case, the characteristics of Sensor C5 will be used in the following analyses. Both FSS characteristics in Tables 7-4 and 7-5 are used in the analysis:

TABLE 7-4 Characteristics of FSS networks in the10 GHz band in accordance with RR Table 21-4 Orbital separations of FSS satellites 4 degrees (Note 1) Transmitting power level e.i.r.p. density levels at the FSS satellites as the function of the off-nadir angles to give the same pfd levels as the ones for the band 10.7-11.7 GHz in Table 21-4 (Note 2) NOTE 1 – Taking into account the current situation of FSS satellite networks in around 11 to 12 GHz band, this can be considered as a realistic assumption. NOTE 2 − The same pfd levels as the ones for the band 10.7-11.7 GHz in Table 21-4 as shown below; Power flux-density level assumption at the Earth’s surface: –150 dB(W/m2 per 4kHz) for 0 <=  <= 5 –150 + 0.5*( – 5) dB(W/m2 per 4kHz) for 5 <  <= 25 –140 dB(W/m2 per 4kHz) for 25 <  <= 90 where  is the angle of arrival of the incident wave above the horizontal plane, in degrees. Rep. ITU-R S.2365-0 27

TABLE 7-5 Characteristics of FSS networks in the 10 GHz band in accordance the table in §4 Orbital separations of FSS satellites 4 degrees (Note 1) Transmitting power level e.i.r.p. density levels at the FSS satellites of –20 dBW/Hz (Note 2) NOTE 1 – Taking into account the current situation of FSS satellite networks in around 11 to 12 GHz band, this can be considered as a realistic assumption. NOTE 2 – From liaison statement from WP 4A, Doc. 7B/89.

Two types of interference analysis were performed: – Direct interference from FSS (space-to-Earth) into EESS (passive) sensors (including the interference into antenna back-lobe). – Interference due to the reflected wave from the Earth’s surface into EESS (passive) sensors. 7.2.1.3.1.2.2 FSS (space-to-Earth) direct interference into EESS (passive) sensors The interference criterion of –166 dBW/100 MHz in Recommendation ITU-R RS.2017 is used. The analysis calculates the interference power levels at given EESS (passive) sensors locations as a result of the transmissions of multiple FSS satellites. Since this interference direction from FSS satellites vary, averaged receiving antenna gain of 0 dBi of EESS (passive) sensors is assumed for the evaluation of aggregate interference. To check the worst-case geometrical conditions, the orbit latitude 0 degree (i.e. EESS (passive) sensors is located in the same plane as that of geostationary orbit) is assumed. The relationship between the altitude of an EESS (passive) sensors and power levels from FSS satellites are shown in Table 7-6. As shown in Table 7-6, the interference level of –166 dBW/100 MHz is exceeded in both cases.

TABLE 7-6 Aggregate interference from multiple FSS (Space-to-Earth) into EESS (passive) receivers

FSS characteristics FSS characteristics assumption in Table 1 assumption in Table 2 Note (pfd level in RR Table 21-4) (Note 1) Interference power –123.92 dBW/100 MHz –128.54 dBW/100 MHz Interference level into EESS criterion of (passive) sensors at –166 dBW/100 the altitude of 699 km MHz is exceeded. (Note 2) NOTE 1 – e.i.r.p. density of –20 dBW/Hz is used for elevation angle greater than 25 degrees. For other angles, the same pfd levels in RR Table 21-4 is assumed. NOTE 2 – Characteristics of Sensor C5 in Table 7-4.

Single entry interference was also examined and results are shown in Table 7-7. Taking into account the antenna pattern of Recommendation ITU-R RS.1813, the back lobe gain (the lowest back lobe gain level with which the off-axis angle is greater than 60 degrees) was calculated as –22.09 dBi for the case of sensor C5.

28 Rep. ITU-R S.2365-0

It should also be noted that, even in the case of single entry FSS satellite interference, the interference power levels exceed the interference criterion of –166 dBW/100 MHz.

TABLE 7-7 Single entry interference from single FSS (space-to-Earth) into EESS (passive) receivers

FSS characteristics FSS characteristics assumption in Table 2a assumption in Table 2b Note (pfd level in RR Table 21-4) (Note 1) Interference power –160.11 dBW/100 MHz –165.99 dBW/100 MHz Interference level into EESS criterion of (passive) sensors at –166 dBW/100 the altitude of 699 km MHz is exceeded. (Note 2) NOTE 1 – e.i.r.p. density of –20 dBW/Hz is used for elevation angle greater than 25 degrees. For other angles, the same pfd levels in RR Table 21-4 is assumed. NOTE 2 – Characteristics of Sensor C5 in Table 7-4.

7.2.1.3.1.2.3 FSS Interference due to the reflected wave from the Earth’s surface into EESS (passive) sensors To take into account the reflection from the Earth’s surface, the reflection factor should be investigated. Report ITU-R P.1008 describes that, in the majority of cases, the reflection factor is 0.1 to 1.2, which corresponds to –10 dB to 0.8 dB. The following analyses used the value of 0.8 dB as the worst-case. Appropriateness of the worst-case value may need to be investigated further, taking into account this specific interference environment. As an example case, the reflection angle of 0 degree is considered since this is the worst-case and simplest case. The calculation result of single entry interference power level is shown in the Tables 7-8 and 7-9. As shown in Tables 7-8 and 7-9, the worst-case single entry interference power levels due to the reflected wave from the Earth’s surface into EESS (passive) sensors do not satisfy the criterion in Recommendation ITU-R RS.2017. It should be noted aggregate interference power level may also be checked in further studies, taking into account number of proposed FSS satellites in geostationary orbits can be visible from EESS (passive) sensors. Rep. ITU-R S.2365-0 29

TABLE 7-8 Single entry interference power level calculation results (with assumption in Table 1)

Parameters Values Note Power flux-density –140 dB(W/m2 per Angle of arrival of 90 degrees 4 kHz) EESS (passive) sensors 97.66 dBm2 Altitude of 699 km footprint area Elliptical area with off-axis of 5 degrees and 10 degrees is taken into account Reflection factor 0.8 dB Worst-case value in Report ITU-R P.1008 (NOTE 1) Free-space loss 169.88 dB Altitude of 699 km EESS (passive) sensors 44.1 dBi From Sensor C5 receiving antenna gain Interference power level –123.33 dBW/100 MHz > –166 dBW/100 MHz NOTE 1 – Appropriateness of the worst-case value may need to be investigated further, taking into account this specific interference environment.

TABLE 7-9 Single entry interference power level calculation results (with assumption in Table 2)

Parameters Values Note FSS satellite e.i.r.p. density –20 dBW/Hz From Table 2B Span loss 162.06 dBm2 GSO altitude of 35 786 km EESS (passive) sensors footprint 97.66 dBm2 Altitude of 699 km area Elliptical area with off-axis of 5 degrees and 10 degrees is taken into account Reflection factor 0.8 dB Worst-case value in Report ITU-R P.1008 (Note 1) Free-space loss 169.88 dB Altitude of 699 km EESS (passive) sensor receiving 44.1 dBi From Sensor C5 in Table 1 antenna gain Interference power level –129.38 dBW/100 MHz > –166 dBW/100 MHz NOTE 1 – Appropriateness of the worst-case value may need to be investigated further, taking into account this specific interference environment. 7.2.1.3.1.2.4 Summary of study #2 With respect to the interference from the proposed FSS (space-to-Earth) into EESS (passive) sensors in the 10.6-10.7 GHz band, the following two interference scenarios were considered: – direct interference from FSS (Earth-to-space) satellite emissions into EESS (passive) sensors (including the interference into antenna back-lobe); – interference due to the reflected wave from the Earth’s surface into EESS (passive) sensors. Regarding direct interference from FSS satellite emission into EESS (passive) sensors, the interference criterion to protect EESS (passive) sensors was not satisfied in either the single entry or aggregate case.

30 Rep. ITU-R S.2365-0

Regarding the single entry interference due to the reflected wave from the Earth’s surface into EESS (passive) sensors, the worst-case analysis showed that the interference levels from the proposed FSS (space-to-Earth) into EESS (passive) sensors do not satisfy the interference criterion to protect EESS (passive) sensors.

7.2.1.3.1.3 Summary of FSS (space-to-Earth) interference into EESS (passive) sensors The interference criterion to protect EESS (passive) sensors in Recommendation ITU-R RS.2017 was not satisfied either for the single entry interference or aggregate interference from proposed FSS satellites (space-to-Earth) into EESS (passive).

7.2.1.3.2 FSS (Earth-to-space) into EESS (passive) This study examines the potential of the proposed FSS Earth-to-space allocation for interference to EESS (passive) sensors in 10.6-10.7 GHz band. The 10.6-10.7 GHz band is currently allocated for EESS (passive). The proposed FSS allocation overlaps with the EESS (passive) allocations.

7.2.1.3.2.1 FSS interference to EESS (passive) 10.6-10.7 GHz band Recommendation ITU-R RS.2017 establishes protection criterion of –166 dBW/100 MHz for the EESS (passive) receivers in the 10.6-10.7 GHz band. Interference analysis was performed to determine whether the interference levels from proposed FSS earth stations into EESS (passive) receivers exceed the protection criterion. In accordance with Recommendation ITU-R RS.1861, Table 7-3 of this report shows specifications for five microwave radiometric systems. As an example case, the characteristics of Sensor C5 is used in the following analyses. As the simplest interference scenario, single entry interference from one FSS earth station into EESS (passive) sensors is taken into account.

7.2.1.3.2.2 FSS (Earth-to-space) interference into EESS (passive) sensors The interference criterion of –166 dBW/100 MHz in Recommendation ITU-R RS.2017 is used. The analysis calculates the interference power levels at given EESS (passive) sensors locations as a result of the transmissions of single FSS earth station. Since these interference directions from FSS earth station vary, averaged receiving antenna gain of 0 dBi of EESS (passive) sensors is assumed for the evaluation of aggregate interference. For the conservatism, the back lobe e.i.r.p. density of ‒6 dBW/40kHz (in accordance with Recommendation ITU-R S.728) of transmitting FSS earth station is assumed. If the interference level from back lobe emission of transmitting FSS earth station exceeds the interference criterion of –166 dBW/100 MHz, such affected area should be calculated, in order to check if such area exceeds the statistical criteria of 0.1% in Recommendation ITU-R RS.2017. The relationship between the altitude of an EESS (passive) sensors and power levels from an FSS earth station are shown in Table 7-10. As shown in Table 7-10, the interference criteria of 0.1% with −166 dBW/100 MHz in Recommendation ITU-R RS.2017 are exceeded. Rep. ITU-R S.2365-0 31

TABLE 7-10 Interference from FSS earth station (Earth-to-Space) into EESS (passive) receivers

Point-to- FSS Earth Station Transmission Type VSAT Wide Band Note Point FSS Earth Station Characteristics Percentage of Total Satellite Transmissions 69.3 4.9 25.8 (%) Range of Peak Antenna Gains (dBi) 37.2 to 50.5 51.7 to 60.8 43.9 to 57.2 Range of Antenna sizes (m) 0.6 to 2.8 3.2 to 9.1 1.3 to 6.0 3dB Beamwidth at 14GHz (degrees) 1.15 0.85 0.74 Maximum Power Spectral Density at –42 –49 –50 antenna port (dBW/Hz) Maximum e.i.r.p. Density (dBW/Hz) 1.5 3 3.5 Minimum Elevation Angle (degrees) 10 10 10 Rec. ITU-R Rec. ITU-R Rec. ITU-R Off-axis Radiation Pattern S.1855 S.580 S.580 Rec. ITU-R Rec. ITU-R Rec. ITU-R Off-axis Power Limits S.728 S.728 S.728 Rec. ITU-R Rec. ITU-R Rec. ITU-R Main Lobe Characteristics BO. 1213 BO. 1213 BO. 1213 Average Band width (MHz) 0.58 30.84 2.94 Antenna Gain (dBi) 50.5 60.8 57.2 Power Density (dBW/Hz) –49.0 –57.8 –53.7 EESS Sensor Characteristics Altitude (km) 699.6 699.6 699.6 Frequency (GHz) 10.6 10.6 10.6 Maximum Beam Gain (dBi) 44.1 44.1 44.1 Antenna Pattern Rec. ITU-R Rec. ITU-R Rec. ITU-R RS.1813 RS.1813 RS.1813 Back Lobe Gain (dBi) 0 0 0 Interference Calculation Elevation Angle (degrees) 0 0 0 Slant Range (km) 3068.2 3068.2 3068.2 Max. value Pass Loss (dB) 122.6 122.6 122.6 Max. value FSS earth station off-axis e.i.r.p. Lowest (back lobe of Rec. ITU-R S.728) –6 –6 –6 value (dBW/40 kHz) Interference Power Density at EESS Sensor Lowest (dBW/100 MHz) values, –117.0 –99.8 –110.0 but ‒166 is exceeded Activity Factor (%) 100 100 100 Note 1 Interference Criteria in Rec. ITU-R –166 –166 –166 RS.2017 (dBW/100MHz) All the Surface Area of Sphere of the EESS 629,504,840 629,504,840 629,504,840 Sensor Altitude (km2)

32 Rep. ITU-R S.2365-0

TABLE 7-10 (end)

Point-to- FSS Earth Station Transmission Type VSAT Wide Band Note Point Interference Calculation Geocentric Angle within the Range where Certain Point on the Earth’s Surface is 25.6 25.6 25.6 visible from EESS Sensor (degrees) Surface Area of Sphere of the EESS Sensor Altitude where Geocentric Angle is smaller 31,111,738 31,111,738 31,111,738 than the above Value (km2) Percentage of Surface Area of Sphere of the EESS Sensor Altitude where 4.94 4.94 4.94 Geocentric Angle is smaller than the above Value (%) Whole Visible Earth’s Surface Area of 65,724,169 65,724,169 65,724,169 EESS Sensor (km2) Measurement Area in Recommendation 10,000,000 10,000,000 10,000,000 ITU-R RS.2017 (km2) Percentage of Area by which Permissible Interference Level in Recommendation 0.75 0.75 0.75 > 0.1 ITU-R RS.2017 (%) Maximum Percentage of Area by which Permissible Interference Level may be 0.1 0.1 0.1 Exceeded in Recommendation ITU-R RS.2017 (%) NOTE 1 – All the time when FSS earth station (even single earth station) is visible from EESS sensor, the interference level from FSS earth station will exceed –166 dBW/100 MHz.

The analysis showed that single entry interference level exceeds the interference criterion of 0.1% with –166 dBW/100 MHz in Recommendation ITU-R RS.2017.

7.2.1.3.2.3 Summary of FSS (Earth-to-space) interference into EESS (passive) sensors With respect to the interference from the proposed FSS (Earth-to-space) into EESS (passive) sensors in the 10.6-10.7 GHz band, the scenario of the single entry direct interference from proposed FSS earth station (Earth-to-space) into EESS (passive) was considered: The interference criterion to protect EESS (passive) sensors in Recommendation ITU-R RS.2017 was not satisfied even for the single entry direct interference from proposed FSS earth station (Earth-to- space) into EESS (passive).

7.2.2 FSS (s-E) and FS According to RR Article 5, FS is allocated on a primary basis in frequency band 10.5-10.68 GHz in Regions 1, 2 and 3. Additional restrictions for FS use in frequency band 10.6-10.68 GHz are described in RR No. 5.482.

7.2.2.1 Technical characteristics and typical parameters of FS stations Table 7-11 provides technical characteristics and typical parameters of digital point-to-point (PP) FS systems in frequency band 10.5-10.68 GHz in accordance with Recommendation ITU-R F.758. Rep. ITU-R S.2365-0 33

Technical characteristics and typical parameters of digital PMP FS systems in frequency band 10.5-10.68 GHz are provided in Table 5-3, § 5.2.1.1.

Permissible long-term aggregate interference level Iag for terrestrial FS stations from GSO-FSS satellites is determined by criteria Iag/N = −10 dB, where N – receiver noise power density typical of FS station under Recommendation ITU-R F.758.

TABLE 7-11 Technical characteristics and typical parameters of digital FS systems in frequency band 10.5-10.68 GHz FS system PP FS system Parameter (1) (2) Frequency band (GHz) 10.5-10.68 Reference ITU-R Recommendation F.747 Modulation QPSK QPSK Channel spacing and receiver noise bandwidth (MHz) 1.25; 2.5; 3.5; 7 1.25; 2.5; 3.5; 7 Tx output power range (dBW) −2 −2 Tx output power density range (dBW/MHz) −10 −10 Feeder/multiplexer loss range (dB) 0 0 Antenna type and gain range (dBi) 49 49 (1) 116.15 116.15 Dant /  e.i.r.p. range (dBW) 47 47 e.i.r.p. density range (dBW/MHz) 39 39 Receiver noise figure typical (dB) 3 3

Receiver noise power density typical (=NRX) −141 −141 (dBW/MHz) Normalized Rx input level for 1 × 10−6 BER −127.5 −127.5 (dBW/MHz) Nominal long-term interference power density −151 −151 (dBW/MHz) (1) Ratio Dant /  is estimated for given maximum antenna gain value in accordance with Recommendation ITU-R F.699.

The antenna pattern for FS stations was assumed according to Recommendation ITU-R F.1245. Information about antenna elevation angles of FS stations that were used during calculations is based on BR IFIC data. According to BR IFIC No. 2737 data (Terrestrial services) from 05.02.2013 there are there are 7 368 records of terrestrial FS stations in frequency band 10.5-10.68 GHz in Region 1 and information about the antenna elevation angle is indicated for 7 110 stations. Weight coefficient W for FS receiver stations with different antenna elevation angle values is provided in Table 7-12. e0

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TABLE 7-12 Distribution of FS stations under antenna elevation angle value in frequency band 10.5-10.68 GHz in Region 1

FS antenna elevation Number of FS stations Weight coefficient angle recorded in the MIFR for W  (degree) Region 1 e0 Frequency band 10.5-10.68 GHz 3…24 62 0.0087 2…3 40 0.0056 1…2 46 0.0065 –1 … +1 6 818 0.9589 –7.4… –1 144 0.0203

7.2.2.2 Compatibility studies 7.2.2.2.1 Calculation results of probability of causing harmful interference to FS terrestrial stations The calculation of average probability Р of interference criterion exceeding of FS stations was done under methodology that is accurately described in Document 4А/317 (2007-2012 study period) that provides estimation of probability of causing harmful interference to FS terrestrial stations from geostationary BSS satellites in the frequency band 21.4-22.0 GHz. This document was considered and approved under study for WRC-12 agenda item 1.13. The input parameters are for estimation of probability Р are presented in § 5.2.1.2.1. Calculation results of probability of permissible interference criterion exceeding for FS terrestrial stations was fulfilled for two cases: – without assumption of FS station antenna beam avoidance from exact pointing on GSO; – in assumption that FS station antenna beams should avoid an exact GSO direction for not less, than ε = 1.5º (similarly to Table 21-1 of RR Article 21). All other azimuth A values are equiprobable except for two prohibited sections χ(ε,φ), where ε = ±1.5º. The calculation results of probability of causing harmful interference to PP FS systems from GSO-FSS (space-to-Earth) in frequency band 10.5-10.68 GHz are provided in Tables 7-13 and 7-14 for different FSS (space-to-Earth) e.i.r.p. spectral density values. Rep. ITU-R S.2365-0 35

TABLE 7-13 Probability of interference criterion exceeding for FSS (space-to-Earth) spectral density e.i.r.p. 40 dBW/MHz, % (NRX(1) = 141 dBW/MHz; NRX(2) = 140 dBW/MHz; NRX(3),(4) = 139 dBW/MHz)

FS system type and PP FS system antenna gain GSO-FSS (1) (2) satellite separation 49 51 Condition (dBi) (dBi) 3 without initial avoidance 2.509% 2.194% 3 with avoidance 1.5° 1.179% 0.895% 10 without initial avoidance 1.315% 1.124% 10 with avoidance 1.5° 0.370% 0.273%

TABLE 7-14 Probability of interference criterion exceeding for FSS (space-to-Earth) spectral density is 34 dBW/MHz, % (NRX(1) = 141 dBW/MHz; NRX(2) = 140 dBW/MHz; NRX(3),(4) = 139 dBW/MHz)

FS system type and PP FS system antenna gain GSO-FSS (1) (2) satellite separation 49 51 Condition (dBi) (dBi) 3 without initial avoidance 0.65% 0.898% 3 with avoidance 1.5° 0.078% 0.028% 10 without initial avoidance 0.335% 0.54% 10 with avoidance 1.5° 0.042% 0.024%

The calculation results of probability of causing harmful interference to PMP FS systems from GSO-FSS (space-to-Earth) in frequency band 10.5-10.68 GHz are provided in Tables 5-5 and 5-6, § 5.2.1.2.1.

7.2.2.3 Summary When GSO-FSS (space-to-Earth) spectral density e.i.r.p. is 40 dBW/MHz the probability of long-term aggregate interference criterion exceeding Iag/N = −10 dB varies: – for stations of PP FS systems in frequency band 10.5-10.68 GHz: from 1.124% to 2.509% without the FS station antenna beam avoidance from an exact GSO direction and from 0.273% to 1.179% with FS station antenna beam initial avoidance from an exact GSO direction for angle not less than 1.5°; – for stations of PMP FS systems in frequency band 10.15-10.68 GHz:

36 Rep. ITU-R S.2365-0

from 4.408% to 8.39% without the FS station antenna beam avoidance from an exact GSO direction and from 3.185% to 7.029% with FS station antenna beam initial avoidance from an exact GSO direction for angle not less than 1.5°. When GSO-FSS (space-to-Earth) spectral density e.i.r.p. is 34 dBW/MHz, the probability of long-term aggregate interference criterion exceeding Iag/N = −10 dB varies: – for stations of PP FS systems in frequency band 10.5-10.68 GHz: from 0.335% to 0.898% without the FS station antenna beam avoidance from an exact GSO direction and from 0.024% to 0.078%with FS station antenna beam initial avoidance from an exact GSO direction for angle not less than 1.5°; – for stations of PMP FS systems in frequency band 10.15-10.68 GHz: from 0% to 1.102% without the FS station antenna beam avoidance from an exact GSO direction and from 0% to 0.488% with FS station antenna beam initial avoidance from an exact GSO direction for angle not less than 1.5°. It is necessary to take into consideration that the given estimation is overestimated as the majority of FS stations operate with margin of signal-to-noise ratio and also because in calculation were not considered interfering signal rain attenuation and its correlation with wanted signal attenuation on FS link. However it should be taken into account that fixed stations possible additional SNR margin cannot be assured and in particular the fade margin of fixed station link is assigned for particular performance requirements and is not designed for interference mitigation.

7.2.3 FSS (s-E) and MS No sharing studies were submitted to the ITU-R for FSS (s-E) satellite systems and mobile systems in the band 10.6-10.68 GHz.

7.2.4 FSS (s-E) and RAS In the frequency band 10.6-10.7 GHz the RAS stations are used for the continuum and very long baseline interferometry (VLBI) observations. In accordance with Recommendation ITU-R RA.769 the threshold interference pfd level is –240 dBW/m2/Hz (Table 1) for continuum observations and –193 dBW/m2/Hz (Table 3) for VLBI observations in the frequency band 10.6-10.7 GHz. In accordance with RR Article 21 Table 21.4 for GSO FSS (space-to-Earth) the following pfd limits apply to the frequency band 10.7-11.7 GHz: − –126 dBW/m2 per 1 MHz for angles of arrival from 0 to 5 deg.; − –126+0.5(δ-5) dBW/m2 per 1 MHz for angles of arrival from 5 to 25 deg.; − –116 dBW/m2 per 1 MHz for angles of arrival from 25 to 90 deg.

7.2.5 FSS (s-E) and SRS (passive) No sharing studies were submitted to the ITU-R for FSS (s-E) satellite systems and SRS (passive) in the band 10.6-10.68 GHz.

7.3 Summary of studies for the band 10.6-10.68 GHz Two static analyses were conducted examining the two scenarios where the EESS passive sensors could receive interference from an FSS GSO satellite. For both scenarios, the EESS (passive) protection criteria was exceeded. In the scenario where the direct signal of the FSS GSO downlink being received by the EESS (passive) antenna backlobe, both studies showed that the EESS (passive) protection criteria was exceeded by 6 to11 dB. For the scenario where the FSS GSO signal is reflected Rep. ITU-R S.2365-0 37 from the earth surface and then received by the EESS sensor (backscatter), both studies show the EESS (passive) protection criteria is exceeded by 21 dB to as high as 42 dB. One static analysis was completed examining compatibility of FSS (E-s) and EESS (passive). The results of this study show that the EESS (passive) protection criteria is exceeded by all three FSS transmission types by at least 49 dB. One study was completed examining the compatibility of FSS (s-E) and FS. In this study, PP and PMP systems were considered with two different FSS e.i.r.p.s and considering cases where FS pointing to the GSO is avoided and cases where the FS pointing to the GSO is not avoided. Considering all situations, the FS protection criteria could be exceeded. No sharing studies were submitted to the ITU-R for FSS (s-E) satellite systems and mobile systems in the band 10.6-10.68 GHz. Material was available for examining the sharing situation between FSS (s-E) and RAS. From the available material it could be seen that the protection criteria of RAS stations would be exceeded by FSS (s-E) operations. No sharing studies were submitted to the ITU-R for FSS (s-E) satellite systems and SRS (passive) systems in the band 10.6-10.68 GHz.

8 Frequency band 13.25-13.4 GHz The allocations of this band in RR Article 5 are shown below.

TABLE 8-1 Excerpts from Article 5 of the Radio Regulations on allocation to services in 13.25-13.4 GHz

Allocation to services Region 1 Region 2 Region 3 13.25-13.4 EARTH EXPLORATION-SATELLITE (active) AERONAUTICAL RADIONAVIGATION 5.497 SPACE RESEARCH (active) 5.498A 5.499 5.497 The use of the band 13.25-13.4 GHz by the aeronautical radionavigation service is limited to Doppler navigation aids. 5.498A The Earth exploration-satellite (active) and space research (active) services operating in the band 13.25-13.4 GHz shall not cause harmful interference to, or constrain the use and development of, the aeronautical radionavigation service. (WRC-97) 5.499 Additional allocation: in Bangladesh and India, the band 13.25-14 GHz is also allocated to the fixed service on a primary basis. In Pakistan, the band 13.25-13.75 GHz is allocated to the fixed service on a primary basis. (WRC-12)

8.1 Review of Recommendations/Reports A list of relevant Recommendations and Reports that may be useful for sharing studies is in Table 8-2.

38 Rep. ITU-R S.2365-0

TABLE 8-2 Summary of relevant Recommendations/Reports that may be useful for sharing studies in the band 13.25-13.4 GHz

Service Relevant Recommendations/Reports Fixed Recommendation ITU-R F.699 Recommendation ITU-R F.758 Recommendation ITU-R F.1107 Recommendation ITU-R F.1245 Recommendation ITU-R F.1333 Recommendation ITU-R F.1336 Recommendation ITU-R F.1777 Recommendation ITU-R F.746 Recommendation ITU-R F.497 Earth exploration-satellite Recommendation ITU-R RS.1166-4 (active) Report ITU-R RS.2068 Aeronautical radionavigation Recommendation ITU-R M.2008 Report ITU-R M.2230 Space research (active) None

The frequency band 13.25-13.4 GHz was considered previously in the studies carried out under WRC-12 agenda item 1.25. The study results are given in Report ITU-R М.2221 and also in the CPM Report to WRC-12. WRC-12 decided not to make an allocation to the MSS in this band.

8.2 Sharing studies for the band 13.25-13.4 GHz 8.2.1 FSS (s-E and E-s) and EESS (active) 8.2.1.1 Overview of EESS (active) systems in the band 13.25-13.75 GHz Earth exploration-satellite service (EESS) (active) satellites with three types of active sensors: scatterometers, altimeters and precipitation radars are in operation in the 13.25-13.75 GHz band. The EESS (active) remote sensing systems are used in backscatter echo mode to monitor weather, climate change, water, similar emergencies, to make accurate measurements of sea level and to predict natural disasters. Although EESS (active) satellites are currently operated by only a limited number of countries, measurements are performed worldwide and the remote sensing data and related analyses are distributed free of charge, used globally, and are for the benefit of the whole international community. Therefore, due to the nature of worldwide operation over land or sea areas of EESS (active) systems, compatibility analyses under WRC-15 agenda item 1.6 in the 13.25-13.75 GHz frequency band, shall not make any distinction between geographical areas. In addition, the availability of the full 13.25-13.75 GHz frequency band is required to meet EESS (active) mission requirements. It should be stressed that in addition to meeting overall availability of data protection criteria, of concern for altimeters and scatterometers are cases where RFI occur in a systematic way at the same location. Should the losses of sensing data occur systematically at the same locations (since FSS earth stations are fixed by nature), these areas would never be observed which will violate the protection criteria of any EESS (active) altimeter and scatterometer mission. Rep. ITU-R S.2365-0 39

ITU-R Study Group 7 recently approved an updated revision of Report ITU-R RS.2068 documenting the current and future use of the band near 13.5 GHz by spaceborne active sensors. EESS (active) systems are crucial for the protection of human life and natural resources. It is necessary to ensure that the EESS (active) systems will not suffer from harmful interference resulting from FSS operations and shall be protected in order to successfully conduct their operations in the 13.25-13.75 GHz band. Should an FSS allocation be considered in this band, adequate RR provisions (output power, antenna gain and e.i.r.p.) will have to be added to ensure maximum FSS deployment consistent with the one used in the sharing studies will not unduly constrain EESS (active) operations in 13.25-13.75 GHz band.

8.2.1.2 Operation of satellite altimeters Satellite-altimeter radars, which are usually nadir-pointing active microwave sensors initially designed for operating over the ocean, exhibited strong capabilities in the study of continental surfaces. The ability of radar altimeters to monitor continental water surfaces and measure their stage elevation has also been demonstrated over a wide variety of inland water bodies. New capabilities of satellite altimetry over continents to survey terrestrial snow covered regions have been demonstrated. The excellent accuracy of the height measurements also enables the survey of the ice-sheets surface elevation, the estimation of their mass balance or their flow and the recovery of pertinent geophysical parameters such as snow pack characteristics and surface roughness. The importance of the use of satellite altimeters has been established for lakes, certain major rivers and wetlands where hydrological information can often be difficult to obtain due to a region's inaccessibility, the sparse distribution of gauge stations, or the slow dissemination of data. Also, new processing methods and applications have been developed for littoral and shallow-water regions. In addition, the capabilities of using altimetric scattering data in Ku band over different land surfaces (e.g. desert, tropical forest, savannahs, boreal regions...) at regional and global scales were demonstrated using the span dataset of Topex–Poseidon and the JASON series of satellites. For example, planned radar altimeter missions (such as SRAL on Sentinel-3 mission) are now designed to acquire topography data over all types of surfaces (sea, coastal areas, sea ice, ice sheets, ice margins and in-land waters).

8.2.1.3 Usage of the 13.25-13.75 GHz frequency band by EESS (active) systems Current altimeters in the 13.25-13.75 GHz frequency band make use of bandwidth up to 350 MHz. Several studies have been carried out that examined the need to extend the bandwidth for altimeters to as much as 500 MHz. These studies examined other effects on the accuracy of height measurement including, sea-state bias, ionospheric effect, tropospheric effect and orbit determination. Previously, it was considered that these effects were large enough to dominate the error budget for the height measurement. Recent work during the development of current instruments (such as SRAL on Sentinel 3) have demonstrated that the impact of these effects on the error budget can now be improved and currently allow to increase the overall accuracy below 1 cm in certain modes. There are also potential changes to the basic design of altimeters that may produce a need for wider bandwidths: multibeam altimeters, scanning altimeters and synthetic aperture altimeters fall into this category. Other designs include frequency agility and frequency hopping. While 350 MHz is the current maximum bandwidth required, it is anticipated that future altimeters will require bandwidths up to 500 MHz and operate in the full band 13.25-13.75 GHz.

40 Rep. ITU-R S.2365-0

In addition, bandwidths up to 500 MHz will be needed to accommodate both an altimeter and a scatterometer on the same spacecraft, operating on different frequency assignments, in order to avoid intra-service interference. Therefore, the availability of the full 13.25-13.75 GHz frequency band is required to meet EESS (active) mission requirements.

8.2.1.4 EESS (active) characteristics Report ITU-R RS.2068 [6] describes the use of the band 13.25-13.75 GHz by the various types of EESS (active) sensors. The interference criteria of EESS active sensors can be found in Recommendation ITU-R RS.1166-4. Three types of instruments are considered under the EESS (active) allocation and are currently in operation within the band 13.25-13.75 GHz as described in § 7.2.1. a) Scatterometers (measures winds at the surface of oceans) The scatterometer is an instrument that provides information on the wind over the ocean near the surface: no other instrument can provide all weather measurements of the global vector winds. For QuikSCAT, two spot beams are available, one having an incidence angle of 46° (corresponding to an EESS off nadir angle of 40° for the inner beam) and the other one having an incidence angle of 54° (corresponding to an EESS off nadir angle of 46° for the outer beam). The SCAT scatterometer (CFOSAT mission) is a new wind scatterometer concept based on rotating fan-beam radar with larger incidence angles (18~50°). This combination of incidence angles is necessary to measure the wind vector (from large incidence) and wave properties (from small incidence). SCAT combines the advantages of both the pencil beam of QuikSCAT (a complete azimuth rotation) and the large swaths of ASCAT. Its antenna has a wide beamwidth along the elevation direction and a narrow beamwidth along the azimuth direction. The main SCAT characteristics are as follows: – incidence angles (on ground): 20°–65; – antenna size: 2 antennas HH and VV: 1.2 m x 0.2 m; – rotation speed: 3.4 rpm; – central frequency = 13.256 GHz; – useful bandwidth: Tx = 0.5 MHz / Rx = 3 MHz; – maximum antenna gain = 30 dBi. b) Precipitation radars Precipitation radars provide the precipitation rate over the Earth’s surface, typically concentrating on rainfall in the tropics. Unprecedented data obtained by one on-board precipitation radar have increased our understanding of mechanisms involved in climate change phenomena, and have brought space and meteorological agencies new information on rainfall characteristics. These systems usually operate over bandwidths around 20 to 30 MHz: currently all systems operate in 13.4-13.75 GHz band (and some in 13.75-14 GHz). The Global Precipitation Mission (GPM) and Feng Yun Rain Measurement (FY-RM) missions will operate dual-frequency precipitation radars at 13.6 and 35.55 GHz. To be more specific, there are two channels at 13.593 and 13.603 GHz each channel being 0.6 MHz wide for GPM DPR and there are four channels around 13.6 GHz, with each channel being 8 MHz wide for the FY-RM PMR2. Rep. ITU-R S.2365-0 41 c) Altimeters (measures oceansʼ currents and height of the oceans): such as Jason, Cryosat, Sentinel, SWOT Altimeters operating in Ku-band are mainly nadir-pointing active microwave sensor designed to measure the time return echoes from ocean and ice surfaces. Functioning in one of two operational modes (ocean or ice) the radar altimeter provides information on significant wave height; surface wind speed; sea surface elevation; sea surface temperature; marine meteorology; ocean salinity; ocean color which relates to ocean currents, the surface geoid and tides; and various parameters over sea ice and ice sheets. JASON 1 and 2 are missions currently in operation using frequency bandwidth within the 13.25-13.75 GHz band. The Ocean Surface Topography Mission (OSTM) on the Jason-2 satellite is an international Earth observation satellite mission that utilizes altimetry instrumentation to measure the sea surface height. It is a joint mission by NOAA, NASA, CNES, and EUMETSAT. Sentinel-3, a project within the framework of Global Monitoring for Environment and Security (GMES) headed by the European Commission (EC), will embark a radio altimeter that will also operate in the 13.25-13.75 GHz frequency band. Future projects like SWOT will not only gather data over oceans but also over land masses in order to measure the height of continental waters. SWOT will incorporate a nadir Ku-band altimeter. These altimeters usually operate within a bandwidth of around 350 MHz. In addition, Report ITU-R RS.2068 provides a rationale for future instruments having bandwidths of up to 500 MHz. All current altimeter systems are centred on 13.575 GHz or 13.6 GHz with bandwidths that operate within 13.4-13.75 GHz. Future altimeters employing bandwidths wider than 350 MHz may use the full available allocated 13.25-13.75 GHz frequency band. The existing flying altimetric missions in Ku-band are as follows: – JASON with two satellites JASON1 and JASON2; – Cryosat 2 using an altimeter SIRAL. The future altimetric missions are as follows: – Sentinel-3 devoted to the Earth monitoring and operational oceanography (2013) embarking the SRAL altimeter; – JASON 3 planned to ensure the continuity with JASON2 (2015); – SWIM which is a new altimeter concept (CFOSAT mission in 2015); – JASON-CS (Jason continuity of service in 2017); – SWOT (Surface Water Ocean Topography) that will embark a JASON altimeter (2020). – JFAM (Japanese Future Altimeter Mission). It should be noted that the SWIM altimeter has a new design concept with 6 rotating beam radars at small incidence (0 to 10°) as described in Fig. 8-1.

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FIGURE 8-1 SWIM altimeter rotating beam antenna

The following Tables provides relevant EESS sensor parameters to be considered in the studies under WRC-15 agenda item 1.6. It should also be recognized that future EESS (active) sensors in this frequency band are not limited to the ones listed in the following tables, as shown in the above future altimetric missions. For example, the preliminary mission study for JFAM shows that it will employ a Nadir pointing radar altimeter with similar RF characteristics as those of JASON-3 altimeter but will have different orbital characteristics as those of JASON-3 altimeter. As for the orbital characteristics of JFAM, the orbital parameters such as altitude of 937 km (repeat period of 10 days) and inclination of 51 degrees are currently defined. Rep. ITU-R S.2365-0 43

TABLE 8-3 Characteristics of current and future flying spaceborne active sensors in the 13.25-13.75 GHz band

Altimeter JASON-3 Mission Sentinel-3 HY2A (OSTM) SWIM SRAL SSALT Altitude (km) 963 1 336 519 814 Inclination (degree) 99.3 66 97.5 98.65 Ascending node LST* 06:00 NSS NSS 10:00 Repeat period, days 14 10 27 Antenna diameter 1.4m 1.2m 0.9m 1.2 m Antenna Pk Xmt gain (dBi) 43 43.2 39 42 Antenna Pk Rcv gain (dBi) 43 43.2 39 42 Polarization VV [RHC] VV L Azimuth scan rate (rpm) 0 (nadir) 0 (nadir) 5.6 0 Antenna beam look angle 0°, 2.43°, 4°, 6, 0 0 0 (degree) 8°, 10° Antenna beam azimuth angle 0 0 0-360° 0 (degree) Transmit Pk pwr (W) 20 25 100 7.1 e.i.r.p. peak (dBW) 56.0 56 59 50.5 Antenna elev. beamwidth 0.9 1.27 2 1.1 (degree) Antenna az. Beamwidth 0.9 1.27 2 1.1 (degree) RF center frequency (MHz) 13.580 13.575 13.575 13.575 RF bandwidth (MHz) 20, 80, 320 320 350 350 Pulsewidth (μs) 102.4 106.0 50 49 Transmit Ave. pwr (W) 8.2 –5.41 10-30 0.66 Pulse repetition frequency 1 000- 2 060 2000-6000 1 900-17.800 (PRF) (Hz) 4 000 Chirp rate (MHz/μsec) 0.2, 0.78, 3.12 3.02 7.14 Transmit duty cycle (%) 40.96 21.63 10-33 1.35-2.65, 9.31 e.i.r.p. Ave (dBW) 52.1 49.33 59 40.2 System noise temperature – 331 K 450 K 3.1 (deg K or Noise Figure dB) Interference Protection –146 –145 (I/N = –3dB) (I/N = –3dB) Criterion dBW/MHz dBW/MHz

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TABLE 8-4 List of Scatterometers

Scatterometer Mission QuikSCAT OCEANS HY2A RapidScat1 SEAWINDS AT-2 Altitude (km) 803 963 720 415 Inclination (deg) 98.6 99.3 98.28 51.65 Ascending node LST* 06:00 06:00 12:00 Repeat period (days) 4 14 2 Antenna diameter 1 m 1.3 m 1 m .75 Antenna Pk Xmt gain (dBi) 41 42 38 Antenna Pk Rcv gain (dBi) 41 42 38 H (inner), H (inner), Polarization HH, VV HH, VV V (outer) V (outer) Azimuth scan rate (rpm) 18 21.14 18 43.63 (HH), 45,50.5 Antenna beam look angle (deg) 40, 46 49.09 (VV) Antenna beam azimuth angle 0-360 0-360 (deg) Transmit Pk pwr (W) 100 120 80 e.i.r.p. peak (dBW) 61.0 62.8 57 Antenna elev. beamwidth (deg) 1.6 1 1.67 2.4/2.2 Antenna az. beamwidth (deg) 1.6 1 1.47 2.1 RF center frequency (MHz) 13.402 13.255.5 13.515 13.4 RF bandwidth (MHz) 0.53 3-6 0.4 0.53 Pulsewidth (μs) 1 700 650-1 200 1 350 1 700 Transmit Ave. pwr (W) 30.6 28.8 Pulse repetition frequency (PRF) 180 180 100-200 200 Hz Chirp rate (MHz/μs) 0.000311765 0.005 0.000311765 Transmit duty cycle (%) 30.6 24 30.6 e.i.r.p. Ave (dBW) 55.9 56.6 System noise temperature, 3.4 dB 3.4 dB (deg K or Noise Figure dB) –145.6 Interference Protection Criterion (I/N = –5 dB) (I/N = –5 dB) (I/N = –5 dB) dBW/MHz 1 This instrument is a payload on the International Space Station.

Rep. ITU-R S.2365-0 45

TABLE 8-5 List of precipitation radars

Precipitation radar

Mission Precipitation GPM DPR Measurement Radar 2 Altitude (km) 407 400/600 Inclination (deg) 65 50 Ascending node LST* NSS NSS Repeat period (days) Antenna diameter 1.6m 5.3m Antenna Pk Xmt gain (dBi) 47.4 55 Antenna Pk Rcv gain (dBi) 47.4 55 Polarization HH, HV Azimuth scan rate (rpm) Antenna beam look angle (deg) ± 17 ± 31 Antenna beam azimuth angle (deg) 0 0 Transmit Pk pwr (W) 1 000 e.i.r.p. peak (dBW) 77.4 Antenna elev. beamwidth (deg) 0.7 0.28 Antenna az. beamwidth (deg) 0.7 0.28 RF center frequency (MHz) 13.600 13.6 RF bandwidth (MHz) 0.6/ 0.6 1 8×4 2 Pulsewidth (μs) 1.6 40 Transmit Ave. pwr (W) 6.7 Pulse repetition frequency (PRF) Hz 4 206 Chirp rate (MHz/μs) 8.75 Transmit duty cycle (%) 0.67 e.i.r.p. Ave (dBW) 55.7 System noise temperature, 5.1 dB 3.5 dB (deg K or Noise Figure dB) Interference Protection Criterion –148.9 dBW/MHz (I/N= –10dB) 1 2 channels of 0.6 MHz 2 4 channels of 8 MHz

The corresponding definitions of the angles listed in Tables 8-3, 8-4, and 8-5 can be found in Fig. 8-2.

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FIGURE 8-2 EESS (active) Spacecraft Angle Definitions

Nadir vector D

H i L Earth normal vector

IFOV

Cross scan direction

h can pat S Spacecraft sin (i ) ground track Sin (a = H 1+ R sin (i-a ) D = R sin (a )

i: incidence angle at footprint centre a: angle off nadir g: total scan angle H: height above mean sea level D: distance to field of view centre R: radius of Earth (not shown in diagram) 1861-06

8.2.1.4.1 Protection criteria for EESS (active) systems in the 13.25-13.75 GHz frequency band Concerning the interference criteria, it is noted that Recommendation ITU-R RS.1166-4 indicates that “In shared frequency bands, availability of altimeter data shall exceed 95% of all locations in the sensor service area in the case where the loss occurs randomly and shall exceed 99% of all locations in the case where the loss occurs systematically at the same locations.” This 99% data availability is equivalent to 99% of the time for all areas of measurement of interest. It should be noted that satisfying both criteria is required to ensure protection of EESS (active) operations. The same availability applies for scatterometers. For precipitation radars, it is stated: “In shared frequency bands, availability of precipitation radar data shall exceed 99.8% of all locations in the sensor service area in the case where the loss occurs randomly.” The interference criteria for altimeters, scatterometers, and precipitation radars in the band 13.25-13.75 GHz are calculated using the threshold protection criteria specified in recommends 2 of Recommendation ITU-R RS.1166-4 and are as follows: – altimeter: I/N of –3 dB Concerning altimeters, a value of –117 dBW/320 MHz was initially provided by ITU-R WP 7C as the protection criteria level. For this reason, this value was used in some of the sharing analyses. This value has been used in most of the compatibility analysis. However, the protection criterion for altimeters is I/N of –3 dB, and it is therefore dependent of the system noise temperature. For JASON-3, as the system temperature is equal to 331 K, the protection criteria level considering an I/N of –3 dB should be equal to Imax = –3 – 228.6 + Rep. ITU-R S.2365-0 47

10log10(331) = –206 dBW/Hz or –146 dBW/MHz. It is recommended to perform future compatibility studies using this value for JASON-3. For SWIM, as the system temperature is equal to 450 K, the recommended protection criteria level to use in future studies should be equal to I max = –145 dBW/MHz. – scatterometer: I/N of –5 dB, –195 dBW/Hz; – precipitation radars: I/N of –10 dB, the permissible threshold interference level for PR and DPR is – 147.8 dBW/MHz, the interference level for the PMR2 is –141.3 dBW/8 MHz or –150.33 dBW/MHz. Concerning scatterometer and precipitation radars, values of –195 dBW/Hz and –147.8 dBW/Hz respectively were initially provided by ITU R WP7C as protection criteria levels. The permissible threshold of interference level for the PRM2 is –141.3 dBW/MHz. Radio satellite altimeters like JASON-3, SWIM or SENTINEL-3 use coherent or incoherent echo processing over several tens of pulses in order to get a measurement. The JASON altimeter transmits a short pulse of microwave radiation in the 13.25-13.75 GHz band and in C band toward the surface (water or land). These pulses are frequency linearly modulated signals and are emitted at regular intervals defined by the Pulse Repetition Frequency (PRF). Any interference which occurs during the altimeter sensor reception of these pulses and having a power exceeding the interference level as defined before, will corrupt the whole series of corresponding sensor pulses. Altimeter sensors measure the peak return power of the sensor transmission pulses and so the altimeter sensor will also be affected by the transient peak power of any interference that might coincide with the reception of reflected sensor pulses. Therefore, in order not to underestimate the impact of the interference caused by FSS earth stations into EESS (active) altimeters, compatibility analyses should be conducted taking into account transient peak powers instead of mean powers since altimeters are especially susceptible to RFI peak powers rather than mean power.

8.2.1.4.2 Measurement Area of Interest In addition to random interference threshold protection criteria that are used for global studies, Recommendation ITU-R RS.1166 protection criteria prescribes 99% data availability to be used in the case of systematic interference for all areas of measurement of interest. Systematic interference is defined as interference at the same points for passes over those points. The interference threshold by which this percentage of data availability is measured is based on the measurement degradation threshold or the I/N level specified in Recommendation ITU-R RS.1166-4. Recommendation ITU-R RS.1166-4 interference threshold criteria is exceeded on a systematic basis when a sensor, gathering data over any measurement area of interest, experiences average interference in excess of interference threshold criteria for the considered sensor. In shared frequency bands, Recommendation ITU-R RS.1166-4 recommended availability of all sensor data, with the exception of precipitation radar, shall exceed 95% of all locations in the sensor service area in the case where the loss occurs randomly and shall exceed 99% of all locations in the case where the loss occurs systematically at the same locations. In the case of precipitation radars, the random data availability criteria is 99.8% and the systematic data availability criteria is not applicable. As an example of measurement areas of interest, the United States Department of Agriculture (USDA) currently obtains global measurements, using the JASON series of sensors, of 83 global reservoirs and lakes. The data obtained and the precise measurement areas for each reservoir and lake is publically available at: http://www.pecad.fas.usda.gov/cropexplorer/global_reservoir/. In addition to the USDA measurement areas of interest, numerous other measurement areas of interest are monitored throughout the world.

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Figure 8-3 provides a depiction of the 83 global points (red dots) monitored in the USDA program. Figure 8-4 provides a view of one of the Measurement Areas of Interest in the USDA program.

FIGURE 8-3 USDA Global Reservoir and Lake Monitoring Program

FIGURE 8-4 USDA Measurement Area of Interest example

The Measurement Area of Interest shown in Fig. 8-4, as the black line, is a small portion of a single orbital pass by JASON-2. The black line represents the sequence of consecutive pixel (or footprint) measurements obtained by the sensor as it passes over the measurement area. The orbit of JASON-2 is carefully controlled so that every 10 days the JASON-2 orbital pass aligns with the pass of 10 days ago. This enables measurements to be taken over the same Measurement Area of Interest every 10 days. The inland area of measurement of interest can vary from 10 pixels to over 300 pixels in length. Each pixel is about 3 square kilometers in size. Rep. ITU-R S.2365-0 49

In the case where the interfering source is fixed (that is, antenna pointing is fixed and transmission is continuous) and where the victim receiver is fixed as well, compatibility according to availability of data exceeding 99% of the time for systematic interference can be determined by conducting a single entry analysis over the measurement area of interest. A single entry analysis can be used where the characteristics defining the interaction between the interfering source and victim receiver are time invariant. Under a single entry analysis, it is appropriate to consider the impact of maximal power interference sources as opposed to typical values that would be considered in global dynamic analysis.

8.2.1.5 EESS (active) antenna patterns EESS (active) antenna patterns are usually described using Bessel type shape. For JASON, the maximum antenna gain is 43.2 dBi and a beamwidth 1.3° at –3 dB. The JASON antenna can be approximated as the following formula.

TABLE 8-6 Antenna gain pattern for JASON Ku-band altimeter

Gain G(f) as a function of off- Pattern Angular range Nadir angle f (degrees) G(f) = 43.2 – 9.92(f)2 dBi f ≤ 1.23⁰ –15 dB first sidelobe G(f) = 28.3 dBi 1.23 ⁰ < f _2.19⁰ G(f) = 43.2 – 25 log(f/0.55) dBi 2.19⁰ < f _29.67⁰ G(f) = 0 dBi 29.67⁰ < f

The antenna pattern to be used for SRAL on board SENTINEL-3 is based on existing measurements of the SRAL antenna and has been extrapolated from Recommendation ITU-R F.1245 as follows: 2 –3  D  G() = Gmax – 2.5  10   for 0    m   

G() = 32 – 5 log (D/) – 15 log  for m  

20 m = Gmax  G1 D degrees

G1: gain of the first side lobe = –8  15 log (D/) The result is shown in Fig. 8-5.

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FIGURE 8-5 Altimeter averaged antenna pattern

For the scatterometers, the SCAT antenna (39 dBi, 1.5° for –3 dB beamwidth) on CFOSAT is as follows (Fig. 8-6):

FIGURE 8-6 Scatterometer antenna patterns (39 dBi, 1.5° at –3 dB)

The antenna pattern that was used in the GPM DPR analysis was a best fit function that was based on the measured pattern during pre-launch testing. It can be found below in Fig. 8-7. Rep. ITU-R S.2365-0 51

FIGURE 8-7 Measured GPM DPR antenna pattern with fitted pattern used in analyses

The antenna pattern of PMR2 is given in Fig. 8-8, which is a best fit function based on the current pre-designed antenna.

FIGURE 8-8 PMR2 fitted antenna pattern

8.2.1.6 Scattering coefficients for soils in Ku bands The scattering coefficients as presented in Fig. 8-9 for soils only at Ku-band HH polarization for 5%, mean, and 95% are derived from Ulaby files (Handbook of radar scattering statistics for terrain, Ulaby, Dobson, Artech House) which provide probability density functions (PDFs) of the radar scattering coefficient σ0 (dB) for nine generalized terrain categories as organized by frequency band, angle of incidence, and linear polarization configuration. The HH polarization and the soil terrain have been selected for computing the curves shown in Fig. 8-9.

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FIGURFE 8-9

The incidence angle is also defined as the satellite look angle (incidence angle seen from the satellite at footprint centre). Using the mean curve in Fig. 8-9, the scattering parameters are as follows: − for the altimeter which is a pure nadir instrument, the scattering coefficient is −1 dB; − for the precipitation radar, an average scattering coefficient of −4 dB has been retained. A precipitation radar has an antenna scan range up to 17°, resulting in a scattering coefficient between –1 dB and –7 dB; − for the scatterometer, with antenna beam angles equal to 40° and 46°, resulting in a scattering coefficient between –11 dB and –14 dB, the retained average scattering coefficient is –12 dB. Concerning the specific case of altimeters, the mean scattering values are not representative of the operation actually met by satellite altimeters, since lands, rivers, lakes can also be monitored. Therefore, the scattering coefficient of 7 dB is adequate since it both covers lands and also hydrological areas. It is to be noted that large rivers or lakes can exhibit much higher coefficients up to 20 dB or more without any wind on the surface.

8.2.1.7 Scattering coefficients for sea and in land waters in Ku-band 8.2.1.7.1 General background The relationship between backscatter (also referred to as scattering) coefficient usually expressed as normalized radar cross section (NRCS) and wind speed has been investigated. It can be noticed that the maximum scattering coefficient is found with no wind and can be higher than 15 dB. The sensing method used by the active sensors in the following studies all use scattering coefficients derived from situations where the sensor transmitter and receiver co-located. This methodology requires the surface to reflect the incident signal back to the receiver. The surface roughness dictates the amount of scattering and thereby how much energy is reflected back to the receiver. A perfectly smooth surface will reflect the RF signal at the same angle of the incident as shown in Fig. 8-10-1. As the roughness is increased, the incident RF signal will begin to scatter more as in Fig. 8-10-2. Currently the only available backscatter coefficients are from sensor measurements where the transmitter is co-located with the receiver. The case of another source reflecting or scattering RF from a surface into the EESS Active has not fully characterized. The use of the scattering coefficient for a co-located receiver may not properly estimate the interference seen by the EESS sensor from a FSS Rep. ITU-R S.2365-0 53

GSO satellite. When one EESS active satellite is just below one FSS satellite where the EESS sensor receives interference from the FSS transmitting signal and when both mainbeams of the EESS and FSS are at the nadir direction, this is the backscattering situation where the reflective wave from the ground is at a maximum.

FIGURE 8-10-1 RF Wave Reflection

i r

FIGURE 8-10-2 RF Wave Scattering

i

Table 8-7 gives the ratio of cells number with greater than 1 dB, to total cells number according to different surface type. It can be seen that scattering coefficients of more than 98% of sea and in land water cells are greater than 1 dB when the incidence angles are less than 15°. For land surface, there are more than 0.94% cells with greater than 1 dB scattering coefficients at incidence angles less than 16.5° scattering

TABLE 8-7 Statistic for different type of surface with greater than 1 dB backscattering coefficients

Incidence angle 0 3 6.75 10.5 14.25 15.75 16.5 (°) ~ ~ ~ ~ ~ ~ ~ 0.75 3.75 7.5 11.25 15 16.5 17.25 Surface type Land 96.42% 46.13% 13.43% 10.50% 6.48% 0.94% 0.082% Sea and in land 100% 100% 100% 100% 98.55% 51.82% 1.42% water Total 98.96% 84.42% 74.95% 74.09% 71.91% 37.10% 1.04%

The operation of JASON over ocean has shown the following scattering coefficients and obviously, when the sea surface is not rough, coefficient up to 25 dB can be met as indicated in Fig. 8-11.

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FIGURE 8-11

Therefore, for sea and large inland waters, a scattering coefficient of 14 dB seems adequate.

8.2.1.7.2 Scattering coefficients obtained for TRMM TRMM does measure backscatter from the surface although it is normally used for measuring backscatter from rainfall to estimate the rainfall rate in the tropics. TRMM is scanning across-track 17° over a 0.6 sec cycle, so the incident angle is changing over the data collection period. Three years (2010-2012) rain-free normalized radar surface cross section σ observation of TRMM PR is averaged at 0.1°×0.1° latitude-longitude cells, categorized into 25 incidence angles range covering from 0°-18.75° with an angle step of 0.75°. Figure 8-12 shows the averaged surface scattering coefficients at different incidence angles. It is to be noted the expert group on active sensors within ITU-R (WP 7C), did not have the possibility to review the data as shown in the following Figure.

FIGURE 8-12 Averaged 3-year scattering coefficients from TRMM PR observation (a) incidence angle of 0°-0.75° (in dB)

Rep. ITU-R S.2365-0 55

(b) incidence angle of 3°-3.75° (in dB)

(d) incidence angle of 10.5°-11.25° (in dB)

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(e) incidence angle of 14.25°-15° (in dB)

(f) incidence angle of 18°-18.75° (in dB)

It is to be noted that the rain-free backscatter would be very dependent upon surface soil moisture content and vegetation conditions, such as having thick canopies. Even when the beam is aligned at nadir, for which a flat surface would have zero incidence angle, if the surface is tilted or sloped because of hills or mountains, the local incidence angle is non-zero, and the radar return would be lower than for nadir returns.

8.2.1.8 Reflected area Concerning the reflected area, it corresponds to a typical area valid for altimeters, scatterometers or precipitation radars in the band 13.25-13.75 GHz. The ground footprint size is an important notion to better understand what the altimeter can really observe and measure. The footprint of an antenna is traditionally defined to be the area on the sea surface within the field of view subtended by the beamwidth of the antenna gain pattern. Usually, in altimetric techniques, the footprint is defined in different ways: – The footprint corresponding to the –3 dB of the antenna pattern (also called the beam limited footprint). Rep. ITU-R S.2365-0 57

– The pulse limited footprint which is the size related to the width of the rising edge altimeter which depends on the height of waves, tides, etc. (but not taking into account areas such as land that could disturb the measurement). It should also be stressed that, in addition to the potential RFI due to FSS transmissions, the EESS (active) sensor receiver may experience the influence from land backscatter (main lobe or side lobes), oceanic surface having anomalous profiles or other unwanted reflections (mispointing errors for example). It is therefore usually agreed to use the value of 2  θ (at –3 dB) as a typical value for the reflected area. For the band 13.25-13.75 GHz, considering the characteristics of the JASON altimeter, the typical reflected area thus equals 2 000 km2. For precipitation radar mission having 47.4 dBi maximum antenna gain, the typical reflected area equals 85 km2 for an altitude of 407 km. Lower reflected areas are found for satellites having lower altitudes such as 350 km. For a 55 dBi maximum antenna gain and an altitude of 400 km, the reflected area equals around 20 km2. For precipitation radar, the reflected area is calculated at nadir. For the scatterometer QUIKSCAT (803 km of altitude, 40 dBi maximum antenna gain), the typical reflected area equals 2 000 km2.

8.2.1.9 FSS (space-to-Earth) characteristics See § 4. 8.2.1.10 Sharing analyses between FSS (space-to-Earth) and EESS (active) 8.2.1.10.1 Sharing analysis#1 8.2.1.10.1.1 Static sharing analysis The study considers two scenarios of interference signal to EESS receiver input caused by FSS transmissions. 1) Direct interference impact. 2) Interference due to the reflected signal. The considered interference scenarios are shown in Fig. 8-13.

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FIGURE 8-13 Interference scenarios

FSS FSS satellite satellite on GSO on GSO

≈36000 км Scenario 1

EESS Scenario 2 satellite

The purpose of this analysis is to compute the amount of radiated energy reached at the satellite active sensor. Scenario 1 is representative of the FSS interference received by the EESS satellite within the backlobe of the EESS antenna. Scenario 2 is representative of the FSS interference received by the EESS satellite through the reflection of the FSS signal on the land/sea and the sent back to the EESS satellite reflected signal. In scenario 2, the received power is derived from the reflection of the FSS waveform according to the formula:

2 PtGt 1  Gr Pr =  4D2 4h2 4 where:

Pt : transmit power of the FSS transmitter

Gt : FSS antenna gain of the transmitter

Gr : EESS antenna gain of the receiver level D : distance between the FSS and the ground h : distance between the ground and the active sensor  : radar cross section of the reflected area A. The link in dB between  and the scattering coefficient 0 is: 0=10 log 10 (σ⁄A), with A = area of the reflected area. Static analysis for scenario 1 This scenario considers the variant of interference impact on the back lobes of EESS antenna pattern. This static analysis presented in Table 8-8 is valid for one GSO satellite. Rep. ITU-R S.2365-0 59

TABLE 8-8 Static analysis of EESS back lobe interference from FSS

Precipitation EESS(active) sensor Units JASON-2 QuikSCAT radar Maximum e.i.r.p. sent by FSS GSO dBW/MHz 40.00 40.00 40.00 satellite Altitude of EESS satellite km 1 336.00 803.00 350.00 Distance GSO – EESS satellite km 34 664.00 35 197.00 35 650.00 Active sensor satellite antenna gain dBi 0.00 ‒10.00 10.00 EESS(active) protection level dBW/MHz ‒146.00 ‒135.00 ‒147.80 Received power on the EESS dBW/m2/MHz ‒165.80 ‒175.94 ‒156.05 satellite through the back lobe Margin dB 19.80 40.94 8.25

A 10 dB backlobe antenna gain is used for precipitation radar as a worst case. Lower backlobe antenna gains can be expected as shown in the following figure. The typical antenna pattern used for GPM is as follows.

FIGURE 8-14 Typical antenna gain pattern for GPM

Static analysis for scenario 2 This scenario considers the option when the interfering signal is reflected from the earth surface and falls into the antenna main lobe of the EESS active sensor. Static analysis No. 1 for scenario 2 The calculations of the interference level at the receiver input of the EESS (active) sensors are presented in Table 8-9.

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TABLE 8-9 Static analysis of EESS reflected interference from FSS

GPM EESS(active) sensor Units JASON-3 QuikSCAT Precipitation radar Maximum e.i.r.p. sent by dBW/MHz 40.00 40.00 40.00 FSS GSO satellite Reflected area km2 2.00 E+03 2.00 E+03 5.00 E+01 Backscatter coeff dB 7.00 –10.00 –5.00 Radar cross section m2 1.00 E+10 2.00 E+08 1.58 E+07 Distance ground – Satellite km 1 336.00 803.00 350.00 EESS altimeter Active sensor satellite dBi 43.90 40.00 47.70 antenna gain EESS(active) protection dBW/MHz –146.00 –135.00 –147.80 level Received pfd on the ground dBW/m2/MHz –122.12 –122.12 –122.12 Received power at the EESS dBW/1 MHz –155.77 –172.25 –168.36 sensor Margin dB 9.77 37.25 20.56

Using a scattering coefficient of 7 dB over soils, with one satellite, the margin is largely positive for altimeters and other active sensors. Should a 14 dB scattering coefficient over oceans/large areas with water for altimeters be used, and 10 neighboring GSO satellites contribute to the scattering effect, the link budget would become as indicated in Table 8-10 below.

TABLE 8-10 Static analysis of EESS backscatter interference from FSS

EESS(active) sensor Units JASON-3 QuikSCAT Precipitation radar Maximum e.i.r.p. sent by FSS dBW/MHz 40.00 40.00 40.00 GSO satellite Number of GSO satellites 10 10 10 Backscatter coeff dB 14.00 –10.00 –5.00 Received power at the EESS dBW/MHz –138.77 –162.25 –158.36 sensor Margin dB –7.23 27.25 10.56

Taking into account a negative margin in case of higher scattering coefficient and multiple GSO satellite, it is therefore necessary to conduct accurate dynamic analysis. Static analysis No. 2 for scenario 2 Concerning GPM, Table 8-11 provides the following static analysis Rep. ITU-R S.2365-0 61

TABLE 8-11 Static analysis of EESS reflected interference from FSS

EESS(active) sensor GPM DPR Reflected area km2 85.44 (79.3 dB) Maximum e.i.r.p. sent by FSS GSO satellite, 40.00 dBW/MHz Distance ground – FSS Satellite, km 35800 Space attenuation, dB 162.07 FSS ground pfd, dBW/(m2MHz) –122.12 Backscatter coefficient, dB 1 –4 –5 Power reflected in 1 MHz, dBW –41.8 –46.8 –47.8 Distance ground – EESS Satellite, km 407 Space attenuation, dB 123.57 Wave length^2, m2 0.02202 (–33.13) Active sensor satellite antenna gain, dBi 47.4 EESS (active) protection level, dBW/MHz −148.9 Received power at the EESS sensor, –162.1 –167.1 –168.1 dBW/MHz Margin, dB 13.2 18.2 19.2

With the assumptions described in these static analysis, the interference level from one FSS having a downlink transmission will not exceed the interference criterion for DPR when surface scattering coefficient is 14 dB. Static analysis No. 3 for scenario 2 The static calculations of the interference level from the reflected FSS transmitting power by the earth surface at the receiver input of the GPM DPR and CPM PMR2 are presented in Table 8-12. The mean value of the scattering coefficient, derived from Fig. 8-12 within § 8.2.1.7.2, for incidences angles of about 0° over land or sea, is about 18.9 dB.

TABLE 8-12 Static analysis of EESS reflected interference from FSS

EESS (active) sensor GPM DPR CPM PMR2 Reflected area (km2) 98.9 (79.95 dB) 15.3 (71.85 dB) Maximum e.i.r.p. sent by FSS 40.00 40.00 GSO satellite (dBW/MHz) Distance ground – FSS 35 800 35 800 Satellite (km) Space attenuation (dB) 162.07 162.07 FSS ground pfd, −122.12 −122.12 dBW/(m2MHz) Backscatter coefficient (dB) 15.8 18.9 15.8 18.9

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TABLE 8-12 (end)

EESS (active) sensor GPM DPR CPM PMR2 Power reflected in 1 MHz −27.0 −23.9 −34.47 −31.37 (dBW) Distance ground – EESS 407 400 Satellite (km) Space attenuation (dB) 134.18 134.05 Wave length^2 (m2) 0.02222 (–33.06) 0.02222 (–33.06) Active sensor satellite 47.7 55 antenna gain (dBi) EESS (active) protection −147.80 −150.33 level (dBW/MHz) Received power at the EESS −145.91 −142.81 −146.58 −143.48 sensor (dBW/MHz) Margin (dB) −1.89 −4.99 −3.75 −6.85

With the assumptions described in the static analysis, the interference level from one FSS with the maximum downlink transmission e.i.r.p. of 40 dBW/MHz will exceed the interference criterion for DPR and PMR2 with a margin of about –5 dB and –7 dB respectively, when surface scattering coefficients are 15.8 dB and 18.9 dB, at an incidence angle of 0°.

8.2.1.10.1.2 Dynamic sharing analysis 8.2.1.10.1.2.1 Dynamic sharing analysis for the altimeters This dynamic analysis is based on a backscattered coefficient of 14 dB for the JASON altimeter and a high density of FSS receiving Earth stations in Europe as shown in Fig. 8-15. One hundred and twenty GSO having a 3° spacing on the GSO arc are in operation. Each GSO satellite looks at a specific Earth station and transmits 40 dBW/MHz. Rep. ITU-R S.2365-0 63

FIGURE 8-15 Deployment of GSO and corresponding earth stations

The corresponding cumulative density function is a follows.

FIGURE 8-16 Cumulative function at the receiver of the JASON-3 altimeter through the reflection of a Space to Earth FSS transmission on the Earth

2 10

1 10

0 10

-1 10

-2 10

Corresponding cumulative % Corresponding

-3 10

-4 10 -230 -220 -210 -200 -190 -180 -170 -160 -150 Received power at the altimeter

The maximum received power on board the altimeter does not exceed –150 dBW/MHz and the threshold level of the protection criterion is –146 dBW/MHz. Therefore, in that specific case, there is no risk of interference. In addition to this simulation corresponding to scenario 2 as in § 8.2.1.10.1.1, it is also necessary to evaluate the amount of interference caused by the reception at the JASON receiver on the EESS antenna backlobe from FSS Space to Earth transmission (scenario 1).

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Using the same deployment as in Fig. 8-15, the simulation has shown that the received interference powers at the altimeter are between –150 dBW and ‒147 dBW/MHz. Therefore, there is no risk of interference in that case.

8.2.1.10.1.2.2 Dynamic sharing analysis for Precipitation radar Dynamic analysis No. 1 between Precipitation radar and FSS (space to Earth) This dynamic analysis is based on a backscattered coefficient of ‒5 dB according to Fig. 8-9 for GPM and a high density of FSS receiving Earth stations in Europe as shown in Fig. 8-15. The simulation shows that the received interference powers at the altimeter are between ‒150 dBW and ‒149 dBW/MHz. Therefore, there is no risk of interference in that case since the interference threshold is ‒148 dBW/MHz. In addition to this simulation corresponding to scenario 2 as in § 8.2.1.10.1.1, it is also necessary to evaluate the amount of interference caused by the reception at the GPM receiver on the EESS antenna backlobe from FSS Space to Earth transmission (scenario 1). Using the same deployment as in Fig. 8-15, the simulation has shown that the received interference powers at the precipitation radar GPM are between –150 dBW and –147 dBW/MHz. Therefore, there is no risk of interference in that case. Dynamic analysis No. 2 between Precipitation radar and FSS (space to Earth) In this dynamic analysis, 120 FSS satellites are assumed at 3° spacing in GSO, and the following FSS downlink e.i.r.p. density limitations are applied: − –35 dBW/ Hz for angles of arrival from 0 to 5 degrees; − –35+0.75(δ-5) dBW/ Hz for angles of arrival δ from 5 to 25 degrees; − –20 dBW/ Hz for angles of arrival from 25 to 90 degrees. It can be noted that this mask is less stringent as the e.i.r.p. limitations already proposed in the corresponding method in the CPM report. The angle of arrival is understood to be the elevation angle of the satellite as seen from the earth. The GPM DPR orbits are simulated during 4 days with a time step of 0.6 second. The GPM locations in this latitude range are used to simulate the aggregate interference. Concerning the deployment model, each FSS satellite is pointing at the nadir direction covers all visible area with the e.i.r.p.s mentioned above. All FSS earth stations are located at the equator and at the same longitude of the corresponding GSO satellites. Taking into account the geometry of the precipitation radar and each point on the Earth, the corresponding incidence angle as seen by the radar is computed and employed in the calculations of the interference power regardless of the incident angle of the signal from the FSS satellites. Then, using the data as shown in Fig. 8-12, the appropriate scattering coefficients are computed. Rep. ITU-R S.2365-0 65

FIGURE 8-17 Cdf of interference received on DPR

As shown in Fig. 8-17, the 120 FSS satellites cause 43.65% of data loss for the DPR interference criterion, which is much larger than the 0.2% of permissible data loss. The 120 FSS satellites create an interference level of –136.4 dBW/MHz for 0.2% of the time to DPR, therefore exceeding the protection criterion of –147.8 dBW/MHz by 11 dB. However, it is to be noted that this analysis reflects a worst case since all the FSS earth stations are all located at the equator, and implements scattering coefficients derived from Fig. 8-12.

8.2.1.10.1.3 Summary of sharing analysis between FSS (space-to-Earth) and EESS (active) Following the static analysis performed in § 8.2.1.10.1.1, the dynamic analysis were performed with JASON and GPM since QuikSCAT shows the highest positive margins and is therefore not as critical as JASON and GPM. One static analysis with the JASON altimeter shows positive margins for a scattering coefficient of 7 dB for one GSO satellite. However, the same static analysis shows a negative margin in a worst case of higher scattering coefficient of 14 dB and 10 multiple GSO satellite. Therefore accurate dynamic analysis were conducted with the JASON altimeter. The dynamic analysis shows compatibility between FSS (space-to-Earth) and EESS (active) altimeters, should each GSO FSS transmit a maximum e.i.r.p. of 40 dBW/MHz within the frequency band 13.25-13.75 GHz. Typical and high scattering coefficients were used, and a dense GSO deployment is implemented. For precipitation radar, one static analysis shows that the interference level from one FSS with the maximum downlink transmission e.i.r.p. of 40 dBW/MHz will exceed the interference criterion for DPR and PMR2 with a margin of about –5 dB and –7 dB respectively, when surface scattering coefficients are 15.8 dB and 18.9 dB, at an incidence angle of 0°. Two static analyses between FSS and precipitation radar, show that the interference level from one FSS having a downlink transmission will not exceed the interference criterion for DPR when surface scattering coefficient is less than 14 dB (see Fig. 8-7). For precipitation radar, one dynamic analysis shows compatibility (1 dB margin), between FSS (space-to-Earth) and EESS (active) using a dense deployment model. This simulation is based on a 40 dBW/MHz transmission GSO FSS e.i.r.p. In addition, this analysis uses a scattering coefficient of –5 dB for soil (see Fig. 8-9).

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Another dynamic study for precipitation radar shows negative margins of 11 dB for 0.2% of time between FSS (space-to-Earth) and EESS (active) using a simplified deployment model. This model assumes that all FSS earth stations are located at the equator at the same longitude of the corresponding GSO satellites. In addition, this analysis uses scattering coefficients as shown in figure 8-12 takes into account that all reflected signals are coherently summarized at the input of the EESS (active) receiver. Eventually, the FSS GSO satellites assumed to cover all visible area with the e.i.r.p. limits stipulated in the Radio Regulations (2012 version) and downlink e.i.r.p. mask is less stringent than the e.i.r.p. limitations to protect assignments of terrestrial services (FS, MS) and RLS

8.2.1.10.2 Sharing analysis #2 – Dynamic analysis 8.2.1.10.2.1 Simulation for SENTINEL-3 altimeter For this simulation, FSS earth stations at different latitudes (i.e. 0°, 10°, 20°, 30°, 40°, 50°, 60° and 70°) have been deployed with an antenna pointed towards a GSO satellite. Several simulations have been performed with different elevation angle between the FSS earth station and the GSO satellite (i.e. elevation of 10°, 20°, 30°, 40°, 60° and 80°). The SENTINEL-3 orbits are simulated during 27 days with a time step of 1 second. Figures 8-18 to 8-21 show the cumulative distribution function of I/N criteria during the simulation period for different latitudes, different elevations and different antenna diameters. The vertical solid line on each Figure represents the I/N = –12.2 dB criteria. Because of the time flying over one FSS ES by one non-GSO EESS active system is limited, short-term protection criteria may also be considered when analysing the interference from non-GSO EESS active systems to FSS ES.

FIGURE 8-18 Cdf of interference received on a 60 cm FSS Earth station located at 20° Latitude by SENTINEL-3

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FIGURE 8-19 Cdf of interference received on a 60 cm FSS Earth station located at 40° Latitude by SENTINEL-3

FIGURE 8-20 Cdf of interference received on a 1.2 m FSS Earth station located at 40° Latitude by SENTINEL-3

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FIGURE 8-21 Cdf of interference received on a 7 m FSS Earth station located at 40° Latitude by SENTINEL-3

Table 8-13 shows an overview for all simulations of the percentage of time (in %) for which the interference generated by SENTINEL-3 towards the FSS Earth station exceed the I/N criteria of 6%.

TABLE 8-13 Percentage of time (in %) for which the EESS (active) interference exceed the I/N criteria of 6%

8.2.1.10.2.2 Simulation for JASON-3 altimeter For this simulation, FSS earth stations at different latitudes (i.e. 0°, 10°, 20°, 30°, 40°, 50°, 60° and 70°) have been deployed with an antenna pointed towards a GSO satellite. Several simulations have been performed with different elevation angles between the FSS earth station and the GSO satellite (i.e. elevation of 10°, 20°, 30°, 40°, 60° and 80°). The JASON-3 orbits are simulated during 10 days with a time step of 1 second. Rep. ITU-R S.2365-0 69

Figure 8-22 shows the cumulative distribution function of I/N criteria during the simulation period for a 60 cm FSS earth station located at 40° latitude. The vertical solid line on each Figure represents the I/N = –12.2 dB criteria.

FIGURE 8-22 Cdf of interference received on a 60 cm FSS Earth station located at 40° Latitude by JASON-3

Table 8-14 shows an overview for all simulations of the percentage of time (in %) for which the interference generated by JASON-3 towards the FSS earth station exceed the I/N criteria of 6%.

TABLE 8-14 Percentage of time (in %) for which the EESS (active) interference exceeds the I/N criteria of 6%

“Na” means no possibility to have such elevation angle at such latitude. “< 0.001” means the interference generated by SENTINEL-3 towards the FSS earth station exceeds the I/N criteria of 6% during less than 0.001%. “0” means due to the orbital parameters of JASON-3, an FSS earth station at these latitudes never see this NGSO.

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8.2.1.10.2.3 Simulation for the QuikSCAT scatterometer For this simulation, FSS earth stations at different latitudes (i.e. 0°, 10°, 20°, 30°, 40°, 50°, 60° and 70°) have been deployed with an antenna pointed towards a GSO satellite. Several simulations have been performed with different elevation angles between the FSS earth station and the GSO satellite (i.e. elevation of 10°, 20°, 30°, 40°, 60° and 80°). The scatterometer QuikSCAT orbits are simulated during 4 days with a time step of 3.33 seconds. (3.33 seconds is antenna scan period). The QuikSCAT antenna pattern is a rotating dish antenna sweeping a circular pattern. As such use is not implemented in the Visualize software (used to perform these simulations), the simulations have been performed using a beam pointing only in one direction. Due to the long period of simulation, it is assume that all possible configurations are considered. As shown with Figs 8-23 and 8-24, the cumulative distribution function of I/N criteria during the simulation period for a 60 cm FSS earth station located at 40° latitude for two different angles looks similar. The angle is made with the velocity vector of the NGSO in a clockwise direction. The vertical solid line on each Figure represents the I/N = –12.2 dB criteria.

FIGURE 8-23 Cdf of interference received on a 60 cm FSS Earth station located at 40° Latitude by QuikSCAT

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FIGURE 8-24 Cdf of interference received on a 60 cm FSS Earth station located at 40° Latitude by QuikSCAT

Table 8-15 shows an overview for all simulations of the percentage of time (in %) for which the interference generated by QuikSCAT towards the FSS earth station exceed the I/N criteria of 6%.

TABLE 8-15 Percentage of time (in %) for which the EESS (active) interference exceed the I/N criteria of 6%

“Na” means no possibility to have such elevation angle at such latitude. “0.017” means the interference generated by SENTINEL-3 towards the FSS earth station exceeds the I/N criteria of 6% during 0.017%.

8.2.1.10.2.4 Summary of sharing analysis #2 With the assumptions described in Sharing analysis #2, the simulations and results presented above depict situations where the interference generated by EESS (active) systems exceed the FSS (s-E) protection criteria for a very limited period of time.

8.2.1.10.3 Sharing analysis #9 – Simulations for the interference from EESS to FSS (s-E) For this simulation, FSS earth stations at different latitudes (i.e. 0°, 10°, 20°, 30°, 40° and 50°) have been deployed with an antenna pointed towards a GSO satellite. Several simulations have been

72 Rep. ITU-R S.2365-0 performed with different elevation angle between the FSS earth station and the GSO satellite (i.e. elevation of 10°, 20°, 30°, 40°, 60° and 80°). The CPM PMR2 orbits are simulated during 12 days with a time step of 1 second. This study was conducted, assuming FSS ES protection criteria like I/N = –2.4 dB (for 0.03% of any month) or I/N = 0 dB (for 0.005% of any month), as described in the Annex 1 of Recommendation ITU-R S.1432. Annex 1 provides information on the apportionment of error performance and availability degradations due to interference into satellite communications systems carrying digital traffic as guidance when applying this Recommendation. Figures 8-25 to 8-27 show the cumulative distribution function of I/N criteria during the simulation period for different transmission type, different latitudes and different elevations. The solid line on each Figure represents the protections criteria of FSS ES (from I/N =–12.2 dB of 100% interfering time to I/N = 0 dB of 0.005% interfering time).

FIGURE 8-25 Cdf of interference received on Point-to-Point type FSS Earth stations located at (a) 0° Latitude and (b) 30° Latitude (a)

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(b)

FIGURE 8-26 Cdf of interference received on VAST type FSS Earth stations located at (a) 0° Latitude and (b) 30° Latitude (a)

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(b)

FIGURE 8-27 Cdf of interference received on Wideband type FSS Earth stations located at (a) 0° Latitude and (b) 30° Latitude (a)

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(b)

With the assumptions described here, especially considering the orbit character of the Non-GSO EESS (active) systems, the simulations’ results presented above show that the interference caused by EESS (active) systems would exceed such levels as I/N = –2.4 dB (for 0.03% of any month) or I/N = 0 dB (for 0.005% of any month). The analysis does not include PMR2 transmit duty cycle. It means, that including transmit duty cycle will decrease the probability of interference from EESS to FSS (s-E)

8.2.1.10.3.1 Summary of simulations for the interference from EESS to FSS (s-E) The performed compatibility study of the FSS (space-to-Earth) with EESS (active) precipitation radar shows that the permissible threshold levels of interference level for FSS earth stations will be exceeded by the interference from PMR2 when using more appropriate FSS ES protection criteria such as I/N = –2.4 dB for 0.03% of any months or I/N = 0 dB for 0.005% of any months the following: In case of interference from PMR2, dynamic analysis for the worst-case shows that interference levels such as I/N = –2.4 dB or I/N = 0 dB. The analysis does not include PMR2 transmit duty cycle. It means, that including transmit duty cycle will decrease the probability of interference from EESS to FSS (s-E).

8.2.1.11 Sharing analyses between FSS (Earth-to-space) and EESS (active) 8.2.1.11.1 Sharing analysis #3 – Dynamic analysis Concerning EESS (active) systems, it is noted that the percentage of time associated with the protection criterion is 1% for the altimeter and scatterometer (systematic interference), and 0.2% for the precipitation radar, according to Recommendation ITU-R RS.1166.

8.2.1.11.1.1 Simulation for the JASON-3 and SENTINEL-3 altimeters In accordance with the deployment model provided in § 4 and a frequency reuse factor of 1.2, 10,090 FSS Earth stations have been deployed worldwide in a frequency band of 250 MHz using a single polarization(see Fig. 8-28).

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Each FSS Earth station is pointing to one GSO satellite chosen randomly between a total of 120 GSO satellites, one each 3 degrees, provided that a minimum elevation angle of 10° is respected. Table 8-16 is an embedded excel file which contains all formula.

FIGURE 8-28 Location of the 10,090 FSS Earth stations

TABLE 8-16 FSS antenna characteristics used in simulations for altimeters (Worst case)

FSS2 Data Nyquist Average Power Occupied Bandwidth allocated Antenna Diameter % of total Average Tx Number of bandwidth Density bandwidth to each type of type (m) Bandwidth Power (dBW) antenna (MHz) (dBW/Hz) (MHz) antenna (MHz) Type 1 0.6 2.2 0.3% -55 8.4 2.64 108 41 Type 2 1 0.6 9.4% -53.8 4.0 0.72 3384 4,700 Type 3 1.5 0.5 3.4% -56.1 0.9 0.6 1224 2,040 Type 4 2.1 4.5 35.2% -56.8 9.7 5.4 12672 2,347 Type 5 3.5 26.2 8.7% -54.8 19.4 31.44 3132 100 Type 6 7 23.9 26.3% -59.9 13.9 28.68 9468 330 Type 7 10 9.4 16.7% -67.6 2.1 11.28 6012 533 Total 10,090

This number of total stations was obtained by considering, as starting point, the statistics of the model provided by one satellite operator (i.e. % of total bandwidth for each type of antenna and occupied bandwidth for each type of antenna) in order to reach the total amount of spectrum used by satellites in this simulation (i.e. 36 000 MHz = 250 MHz  1.2  120 satellites). The Sentinel-3 and JASON-3 orbits are simulated during 27 days with a time step of 1 minute. The antenna pattern used is based on existing measurements of the SRAL antenna pattern which will be used on board SENTINEL-3. It should be noted that compared to Recommendation ITU-R F.1245 which is traditionally used in sharing studies, including outside FS, the measurements exhibit higher average side-lobe levels in the far side lobes, and lower first side lobe levels. It is proposed to use the following pattern as shown in Fig. 8-5. It should be noted that the altimeter SRAL will acquire topography data over all types of surfaces covered by the Sentinel-3 mission (sea, coastal areas, sea ice, ice sheets, ice margins, in-land waters). SRAL will provide measurements with a high spatial resolution (~300 m along-track) over specific dynamic ocean regions, coastal regions (up to 300 km offshore), sea-ice and inland areas. The measurements are therefore not limited to oceans. Rep. ITU-R S.2365-0 77

FIGURE 8-29 Cdf of interference received on SENTINEL-3 & JASON

As shown in Fig. 8-29, the 10,090 FSS earth stations create an interference level of –133.5 dBW for 1% of the time in SENTINEL-3 SRAL receiver and –134.4 dBW for 1% of the time in JASON SRAL receiver, therefore not exceeding the protection criterion of –117 dBW/320 MHz with a positive margin of about 17 dB. For these simulations, the FSS earth station characteristics of one FSS operator were used and an FSS transponder with a bandwidth of 250 MHz is assumed. In practice, based on the type of service offer, this 250 MHz could be split in 8 transponders of 26 MHz or 6 transponders of 36 MHz or 4 transponders of 54 MHz or 3 transponders of 72 MHz or a mixt. Therefore, due to the required guard band between transponders, in any case the occupied bandwidth will not be equal to 250 MHz but around 210/220 MHz. Therefore, if we consider 8 transponders of 26 MHz, the occupied bandwidth will be equal to 208 MHz and the maximum number of FSS Earth station which could be deployed worldwide will be equal to only 8,395, which represent a reduction of around 23% of the total number of Earth station considered in these simulations. However, it should be noted that when the average earth station characteristics of the model contained in Report ITU-R S.2364 [4], derived from the combined deployment data of two FSS operators, that a global deployment of 10,650 earth stations is found. The deployment model in Report ITU-R S.2364 provides information on the number of GSO FSS transmissions per satellite, their average characteristics, and parameter deviation distribution information, over the entire 14-14.5 GHz allocated band. Guardbands between carriers and transponders are inherently accounted for in deployment model in Report ITU-R S.2364 earth station parameters; that is, when the average bandwidths are used there is unused bandwidth corresponding to the individual carrier and transponder guardbands when also taking into account the current FSS GSO FRF in 14-14.5 GHz. Deviating from using the average bandwidth per transmission type would require adjusting the number of transmissions for the transmission types affected.

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8.2.1.11.1.2 Simulation for the QuikSCAT scatterometer The scatterometer bandwidth has been assumed to be 1 MHz, so we considered that one Earth station has a bandwidth of at least 1 MHz. Therefore, as we considered 120 GSO satellites, one each 3 degrees, with a frequency reuse factor of 1.2, 144 (120  1.2) FSS Earth stations (number of GSO satellite x frequency reuse factor) have been deployed worldwide in a frequency band of 1 MHz (see Fig. 8-30). Each FSS Earth station is pointing to one GSO satellite chosen randomly between a total of 120 GSO satellites, one each 3 degrees, provided that a minimum elevation angle of 10 degrees is respected. The same repartition of antennas deployed in 250 MHz observed in Table 8-16 is used to assess the number of each type of antenna in 1 MHz. Table 8-17 is an embedded excel file which contains all formula.

FIGURE 8-30 Location of the 144 FSS Earth stations

TABLE 8-17 FSS antenna characteristics used in simulations for scatterometer

FSS2 Data Nyquist Average Power Number of Number of antenna Antenna Diameter % of total Average Tx bandwidth Density antenna in in 1 MHz type (m) Bandwidth Power (dBW) (MHz) (dBW/Hz) 250 MHz Exact Arrondi Type 1 0.6 2.2 0.3% -55 8.4 41 0.58 1 Type 2 1 0.6 9.4% -53.8 4.0 4,700 67.07 67 Type 3 1.5 0.5 3.4% -56.1 0.9 2,040 29.11 29 Type 4 2.1 4.5 35.2% -56.8 9.7 2,347 33.49 33 Type 5 3.5 26.2 8.7% -54.8 19.4 100 1.42 2 Type 6 7 23.9 26.3% -59.9 13.9 330 4.71 5 Type 7 10 9.4 16.7% -67.6 2.1 533 7.61 7 Total 10,090 144

The QuikSCAT orbits are simulated during 4 days with a time step of 3.33 seconds. It should be noted that taking account of the actual scatterometer bandwidth of 0.6 MHz would not change anything as the decrease in the VSAT output power would be compensated by the decrease in the EESS noise level. The same antenna pattern was used as for the altimeter. Rep. ITU-R S.2365-0 79

FIGURE 8-31 Cdf of interference received on QuikSCAT generated by all antennas

As shown in Fig. 8-31, the 144 FSS earth stations create an interference level of –163 dBW for 1% of the time, therefore not exceeding the protection criterion with a positive more than 28 dB. As the number of Earth stations considered in these simulations is relatively low (only 144 compared to the 10,090 in 250 MHz), the statistical antenna type repartition as defined in Table 8-17 may not be observed in practice. Therefore similar simulations are performed considering that only 1 type of antenna is used for each of the 144 FSS Earth stations. As shown in Fig. 8-32 and Table 8-18, even if only 1 type of antenna is considered, the 144 FSS Earth stations create an interference level that does not exceed the protection criterion of –135 dBW/1 MHz with positive margins between 26 dB up and 39 dB.

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FIGURE 8-32 Cdf of interference received on QuikSCAT generated by each type of antenna

TABLE 8-18 Results of the simulation for each type of antenna

Antenna Type Interference level in dBW for 1% of the time Type 1 –161.2 Type 2 –162.1 Type 3 –165.2 Type 4 –163.4 Type 5 –160.9 Type 6 –166.5 Type 7 –173.7

8.2.1.11.1.3 Summary of sharing analysis #3 With the assumptions described in Sharing analysis #3, the dynamic simulations depict situations where the EESS (active) protection criteria is always met for all kinds of sensors considered, with a positive margin ranging 4.4 to 39 dB.

8.2.1.11.2 Sharing analysis #4 – Dynamic analysis Concerning EESS (active) systems, it is noted that the percentage of time associated with the protection criterion is 1% for the altimeter and scatterometer (systematic interference), and 0.2% for the precipitation radar, according to Recommendation ITU-R RS.1166. Rep. ITU-R S.2365-0 81

8.2.1.11.2.1 FSS TDMA Network characteristics for simulations It is a simplifying assumption of the FSS ES deployment model described in Report ITU-R S.2364 that any TDMA network (typically occurring only in the VSAT transmission type) is to be represented by a single continuous carrier from one VSAT earth station. This assumption may misrepresent the impact of the interference caused by the TDMA network earth stations to a victim receiver. In order to assess this assumption, an initial set of FSS TDMA network parameters were developed for the three FSS transmission types and used in simulations As is the case with all models used in analysis, this set of FSS TDMA network parameters is put forward as an analysis tool and is not intended to represent a faithful reproduction of the FSS TDMA network environment. A summary of the initial set of parameters of FSS TDMA networks for the three transmission types are provided in Table 8-19.

TABLE 8-19 Initial Set of FSS TDMA Network Parameters

VSAT Wideband Point-to-Point ESs/VSAT network 25 11 11 Burst length 10 ms 30 ms 30 ms Frame/segment length 250 ms 400 ms 400 ms The line of reasoning used in creating this initial set of FSS TDMA Network parameters are as follows: The details of the representative TDMA network should provide enough information to: 1) Represent the number of active TDMA ESs assigned to each transmission carrier. 2) Simulate the burst length and repetition rate of the TDMA ES transmission. The operation of a TDMA network is based on the following characteristics: 1) Within a single TDMA network using one specific frequency band (a VSAT carrier in the FSS deployment model) a number of earth stations are deployed. Of earth stations within the single TDMA network only a small percentage of them are actually transmitting, at any given time, in accordance to the needs of that particular earth station and access granted by a central coordination point. 2) The access to a specific frequency band is structured on a prearranged time arrangement of repeating frames (sometimes called segments) and time slots within the frame/segment. The access, granted by a central location, provides the requesting earth station an assignment of a particular time slot (or set of time slots) within the frame. 3) The bandwidth request of the TDMA earth station occurs on a separate channel from that of the timeslots assigned for data transmission. This request can occur through a separate uplink channel accessed using an uncoordinated protocol such as ALOHA or by a telephone line. The request can also be made through a timeslot set aside for requests in the frame/segment. In order to represent this TDMA network operation in a simulation assessing the impact on the victim receiver the required parameters are: 1) The percentage of TDMA networks in each of the three GSO FSS transmission types. 2) The length of a frame/segment; that is, what is the repeat cycle of the burst transmissions from a TDMA earth station. 3) The length (in milliseconds) of those transmissions by an earth station; that is, what is the time slot length within a frame/segment.

82 Rep. ITU-R S.2365-0

4) How many earth stations in a TDMA network are, on average, accessing the carrier at any given time (Number of earth stations assigned timeslots within a frame/segment). (This is derived from 2 and 3.) The overall number of earth stations in a TDMA network (active plus those in idle state) is not needed. We only need to know how many of them are active at any given time. The next two sections provide an application of this methodology to arrive at an initial set of TDMA network characteristics that were used in simulations. A summary of this set of characteristics is provided in Table 8-19.

8.2.1.11.2.2 VSAT TDMA Network characteristics The following set of VSAT TDMA network characteristics will be used to initially assess the impact of the TDMA earth stations to EESS receivers operating in the 13.25-13.75 GHz band. 1) It is initially assumed that 100% of the carriers in the VSAT transmission type are being used in TDMA networks. The percentage of TDMA networks in the VSAT transmission type could be varied between 50% to 100% to take into account errors in this current estimate and also future modifications to FSS marketplace demands. Remaining VSAT transmission types would be non-TDMA (that is, continuous carrier). 2) The length of the frame/segment is assumed to be 250 milliseconds long. This would result in 4 transmission bursts per second from an active VSAT TDMA earth station. 3) The time slots during which a TDMA ES transmits within a frame/segment are assumed to be 10 milliseconds long. 4) The assumptions of 2 & 3 result in 25 active VSAT TDMA earth stations accessing a single carrier at any given time. 5) The implementation of the request channel in deployment is ignored as its impact on the total amount of interference is considered to be insignificant.

8.2.1.11.2.3 Wideband and Point-to-Point TDMA network characteristics The following set of Wideband and Point-to-Point TDMA network characteristics will be used to initially assess the impact of the TDMA earth stations to EESS receivers operating in the 13.25-13.75 GHz band. This is based on the characteristics of the L-3 VMES TDMA system. 1) It is initially assumed that 50% are being used in TDMA networks. The percentage of the carriers in the Wideband and Point-to-Point transmission type could be varied between 0% to 100% to take into account errors in this current estimate and also future modifications to FSS marketplace demands. Currently, a small percentage of the Wideband and Point-to-Point transmission types are TDMA. 2) The length of the frame is assumed to be 400 milliseconds long. This results in 2.5 transmission bursts per second from an active Wideband or Point-to-Point TDMA earth station. 3) 11 active Wideband or Point-to-Point VMES TDMA earth stations are assumed to be accessing a single carrier at any given time. From literature describing the L-3 VMES TDMA system there can be between 7 and 15 active earth stations in its TDMA network; a mean value of 11. 4) The time slots within a frame are assumed to be 30 milliseconds long. The TDMA frame is 400 ms of which some portion is used for network coordination; this is assumed to occupy 17% of the .overall frame. About 330 ms are available for TDMA Rep. ITU-R S.2365-0 83

communications. 330 ms divided by 11 earth stations results in bursts of 30 ms (on average) from each VMES TDMA earth station. 5) The implementation of the request channel in deployment is ignored as its impact is considered to be insignificant. In order to assess the long term compatibility of FSS (E-s) and EESS (active) operations parametric studies have been performed between three sensors representing the three types of EESS (active) sensors that operate in the 13.25-13.75 GHz band. The altimeter studied is JASON-3, the scatterometer – RapidScat, and the precipitation radar – GPM-DPR. The characteristics for these instruments can be found in Tables 8-3, 8-4, and 8-5 above.

8.2.1.11.2.4 Peak to Average Power Ratio The effect of Peak to Average Power Ratio (PAPR) was considered for each of the three types of EESS (active) sensors studied. PAPR is in reference to the fact that the symbols within a transmission modulation have different levels of power. The mean power of a transmission is the average of all the transmitted symbol powers and the peak envelope power is the power of the symbol within the transmission that has the greatest power. For a given modulation, symbols that occur with higher power than the mean power decrease in occurrence as a percentage of time with the increasing power of the particular symbol. Victim receivers that detect average power are not affected additionally by transient transmissions of modulation symbols with higher power than the average. Sensor receivers that detect peak power are sensitive to the transient transmission of modulation symbols that occur above the average power of the ES transmission. When considering interference sources where the PSD or e.i.r.p. of those sources is provided as the average power, additional consideration is needed to account for the impact of the peak envelope power of those interference sources on peak detecting victim receivers. An examination of the frequency of symbols with higher power in comparison to the frequency of detection by the victim receiver is needed to determine the level of PAPR that should be taken account of in the studies. Figure 8-33 provides the results of CCDF measurements made of the power peaks resulting from five commonly used modulation schemes when presented with a random generated data stream. As is expected, 50% of the time peak power is 0 dB above the average power. However, 1% of the time, four of the five modulation schemes have power peaks 4 dB higher than the average. Table 8-20 below tabulates the power peaks for the modulation schemes at the 10%, 1%, 0.1%, and 0.001% levels vs the transmission type bandwidths and provides the number of symbols per second that would occur at those power peaks. Figure 8-33 and Table 8-20 provide the results when considering single carrier transmission per FSS earth station operation. When ESs employ multiple carriers within a transmission (multicarrier operation) the PAPR can increase significantly. Taking the multicarrier characteristic and its impact to PAPR into account for simulations will require further study.

84 Rep. ITU-R S.2365-0

FIGURE 8-33 CCDF of Peak Power for Common Modulations Employed

TABLE 8-20 Tabulation of PAPR as a percentage of time and the corresponding symbols/s for the FSS transmission types

10% of time above Symbols/sec Symbols/sec Symbols/sec Symbols/sec average (dB) (k) 1% (k) 0.1% (k) 0.01% (k) VSAT - 580 KHz 16 APSK 2.6 232 4.0 23.2 4.8 2.3 5.3 0.2 32 APSK 3.2 290 4.6 29 5.5 2.9 6.1 0.3 16 QAM 3.1 232 4.5 23.2 5.6 2.3 6.3 0.2 BPSK 2.8 58 4.4 5.8 4.9 0.6 5.2 0.1 QPSK 2.0 116 3.5 11.6 4.3 1.2 4.7 0.1 Wideband - 30.84 MHz 16 APSK 2.6 12336 4.0 1232 4.8 123.2 5.3 12.4 32 APSK 3.2 15420 4.6 1540 5.5 154.0 6.1 15.5 16 QAM 3.1 12336 4.5 1232 5.6 123.2 6.3 12.4 BPSK 2.8 3084 4.4 308 4.9 30.8 5.2 3.1 QPSK 2.0 6168 3.5 616 4.3 61.6 4.7 6.2 Point-to-Point - 2.94 MHz 16 APSK 2.6 1176 4.0 117.6 4.8 11.8 5.3 1.2 32 APSK 3.2 1470 4.6 147 5.5 14.7 6.1 1.5 16 QAM 3.1 1176 4.5 117.6 5.6 11.8 6.3 1.2 BPSK 2.8 294 4.4 29.4 4.9 2.9 5.2 0.3 QPSK 2.0 588 3.5 58.8 4.3 5.9 4.7 0.6

Rep. ITU-R S.2365-0 85

Since JASON-3 has a sample rate of about 2000 radar echoes per second. The area highlighted in yellow in Table 8-20 indicates in the tabulation where the symbols per second rate exceed the JASON-3 sample rate. An examination of these highlighted entries indicates that in considering the effect of PAPR in the compatibility studies concerning JASON-3 where the Mean power spectral density or e.i.r.p. is known a minimum value of 4 dB should be applied for the VSAT transmission type, a minimum value of 4.7 dB should be applied to the Wideband transmission type, and a minimum value of 4.3 dB should be applied for the Point-to-Point transmission type. The characteristics for the FSS (E-s) deployments considered in these studies come from § 5 above and Report ITU-R S.2364.

8.2.1.11.2.5 Parametric studies of FSS deployment: FRF 1.2 to 5 Table 8-23 provides the results of parametric studies examining the FSS Frequency Reuse Factor as it varies from 1.2 (current implementation) to an FRF of 5 which is assumed to be the upper bound achievable in the foreseeable near-term to long-term future (out to 30 years). The FSS deployment numbers for the simulations of Table 8-23 are provided in Table 8-22. In addition, the current FSS deployment (CFD) documented in Report ITU-R S.2364 was also considered. These results are provided in regards to the protection criteria threshold and the 1% availability exceedance for the altimeter and scatterometer and correspondingly .2% availability exceedance for the precipitation radar. The analysis providing the results of Table 8-23 used the assumption that the entire FSS deployment of ESs was single continuous transmission carrier. The e.i.r.p. of the earth stations in the simulated deployments were varied using the median e.i.r.p. reported by two FSS operators, a 1-sigma increase of e.i.r.p., and a 2-sigma increase in e.i.r.p. These were calculated from the PSD cumulative graphs provided by the two FSS operators which are documented in Report ITU-R S.2364. The e.i.r.p. values used in the simulations can be found in Table 8-21 below.

TABLE 8-21 Values of e.i.r.p. used for the three transmission types

VSAT Wideband Point-to-Point Median –9.23 –3.4 –5.62 E.I.R.P. +1 sigma –6 0.5 –2 E.I.R.P. + 2 sigma –4.8 1 3

The percentage of deployment occupied by the three transmission types (VSAT, Wideband, Point-to-Point) were varied as well in order to assess changes in demand by the future FSS market place. Four different sets of FSS deployments with varying percentages of total transmissions were considered. The variations considered were: 1) 5% VSAT, 5% Wideband, and 90% Point-to-point 2) 25% VSAT, 5% Wideband, and 70% Point-to-point 3) 45% VSAT, 5% Wideband, and 50% Point-to-point 4) 65% VSAT, 5% Wideband, and 30% Point-to-point 8.2.1.11.2.6 Dynamic analysis results for all sensors The number of FSS earth stations used in the simulations are provided in Table 8-22.

86 Rep. ITU-R S.2365-0

TABLE 8-22 FSS Earth Station Deployment numbers for the parametric studies

Pt Pt

- -

to to

- -

VSAT VSAT

spacing spacing

Pt Pt

FSS satellite FSS

Wideband Wideband FSS 120 per FSS 120 per

per satellite per FSS

satellites 3 degree 3 degree satellites 3 degree satellites

FRF 1.2, JASON-3, 250 MHz FRF 2, JASON-3, 250 MHz

CFD (V-68,W- CFD (V-68,W- 127.00 9.00 50.00 186.00 22320 211.67 15.0 83.33 310.00 37200 5,P-27) 5,P-27)

V-5,W-5,P-90 6.00 6.00 110.00 122.00 14640 V-5,W-5,P-90 10.00 10.00 183.33 203.33 24400

V-25,W-5,P- V-25,W-5,P-70 34.00 7.00 96.00 137.00 16440 56.67 11.67 160.00 228.33 27400 70

V-45,W-5,P- V-45,W-5,P-50 70.00 8.00 78.00 156.00 18720 116.67 13.33 130.00 260.00 31200 50

V-65,W-5,P- V-65,W-5,P-30 117.00 9.00 54.00 180.00 21600 195.00 15.00 90.00 300.00 36000 30

FRF 1.2, RapidScat, 0.53 MHz FRF 2, RapidScat, 0.53 MHz CFD (V-68,W- CFD (V-68,W- 0.20 0.02 0.10 0.32 38 0.33 0.03 0.17 0.53 63 5,P-27) 5,P-27)

V-5,W-5,P-90 0.01 0.01 0.20 0.22 26 V-5,W-5,P-90 0.02 0.02 0.33 0.37 43

V-25,W-5,P- V-25,W-5,P-70 0.07 0.15 0.20 0.42 50 0.12 0.25 0.33 0.70 83 70

V-45,W-5,P- V-45,W-5,P-50 0.15 0.02 0.02 0.18 22 0.25 0.03 0.03 0.31 37 50

V-65,W-5,P- V-65,W-5,P-30 0.25 0.02 0.12 0.39 47 0.42 0.03 0.20 0.65 78 30

FRF 1.2, GPM DPR, 1.2 MHz (0.6, 0.6) FRF 2, GPM DPR, 1.2 MHz (0.6, 0.6)

CFD (V-68,W- CFD (V-68,W- 0.61 0.04 0.23 0.88 106 1.02 0.07 0.38 1.47 177 5,P-27) 5,P-27)

V-5,W-5,P-90 0.03 0.03 0.51 0.57 68 V-5,W-5,P-90 0.05 0.05 0.85 0.95 113

V-25,W-5,P- V-25,W-5,P-70 0.16 0.03 0.45 0.64 77 0.27 0.05 0.75 1.07 128 70

V-45,W-5,P- V-45,W-5,P-50 0.33 0.04 0.37 0.73 88 0.55 0.06 0.61 1.22 147 50

V-65,W-5,P- V-65,W-5,P-30 0.55 0.04 0.26 0.85 102 0.93 0.07 0.43 1.42 170 30

Rep. ITU-R S.2365-0 87

TABLE 8-22 (continued)

Pt Pt

- -

to to

- -

VSAT VSAT

spacing spacing

Pt Pt

Wideband Wideband FSS 120 per FSS 120 per

per FSS satellite per FSS satellite per FSS

satellites 3 degree 3 degree satellites 3 degree satellites

FRF 3, JASON-3, 250 MHz FRF 4, JASON-3, 250 MHz

CFD (V-68,W- CFD (V-68,W- 317.50 22.50 125.00 465.00 55800 423.33 30.00 166.67 620.00 74400 5,P-27) 5,P-27)

V-5,W-5,P-90 15.00 15.00 275.00 305.00 36600 V-5,W-5,P-90 20.00 20.00 366.67 406.67 48800

V-25,W-5,P- V-25,W-5,P-70 85.00 17.50 240.00 342.50 41100 113.33 23.33 320.00 456.67 54800 70

V-45,W-5,P- V-45,W-5,P-50 175.00 20.00 195.00 390.00 46800 233.33 26.67 260.00 520.00 62400 50

V-65,W-5,P- V-65,W-5,P-30 292.50 22.50 135.00 450.00 54000 390.00 30.00 180.00 600.00 72000 30

FRF 3, RapidScat, 0.53 MHz FRF 4, RapidScat, 0.53 MHz

CFD (V-68,W- CFD (V-68,W- 0.50 0.05 0.25 0.80 95 0.67 0.07 0.33 1.07 127 5,P-27) 5,P-27)

V-5,W-5,P-90 0.03 0.03 0.50 0.55 65 V-5,W-5,P-90 0.03 0.03 0.67 0.73 87

V-25,W-5,P- V-25,W-5,P-70 0.18 0.38 0.50 1.05 125 0.23 0.50 0.67 1.40 167 70

V-45,W-5,P- V-45,W-5,P-50 0.38 0.04 0.04 0.46 55 0.50 0.06 0.06 0.61 73 50

V-65,W-5,P- V-65,W-5,P-30 0.63 0.05 0.30 0.98 118 0.83 0.07 0.40 1.30 157 30

FRF 3, GPM DPR, 1.2 MHz (0.6, 0.6) FRF 4, GPM DPR, 1.2 MHz (0.6, 0.6)

CFD (V-68,W- CFD (V-68,W- 1.53 0.11 0.57 2.21 265 2.04 0.15 0.76 2.95 353 5,P-27) 5,P-27)

V-5,W-5,P-90 0.07 0.07 1.28 1.42 170 V-5,W-5,P-90 0.10 0.10 1.71 1.90 227

V-25,W-5,P- V-25,W-5,P-70 0.40 0.08 1.12 1.60 193 0.53 0.11 1.49 2.13 257 70

V-45,W-5,P- V-45,W-5,P-50 0.82 0.09 0.92 1.83 220 1.10 0.12 1.22 2.44 293 50

V-65,W-5,P- V-65,W-5,P-30 1.39 .11 0.64 2.13 255 1.85 0.14 0.85 2.85 340 30

88 Rep. ITU-R S.2365-0

TABLE 8-22 (end)

VSAT

spacing

Wideband FSS 120 per

per FSS satellite per FSS

satellites 3 degree 3 degree satellites

FRF 5, JASON-3, 250 MHz

CFD (V-68,W- 529.17 37.50 208.33 775.00 93000 5,P-27)

V-5,W-5,P-90 25.00 25.00 458.33 508.33 61000

V-25,W-5,P-70 141.67 29.17 400.00 570.83 68500

V-45,W-5,P-50 291.67 33.33 325.00 650.00 78000

V-65,W-5,P-30 487.50 37.50 225.00 750.00 90000

FRF 5, RapidScat, 0.53 MHz

CFD (V-68,W- 0.83 0.08 0.42 1.33 158 5,P-27)

V-5,W-5,P-90 0.04 0.04 0.83 0.92 108

V-25,W-5,P-70 0.29 0.63 0.83 1.75 208

V-45,W-5,P-50 0.63 0.07 0.07 0.77 92

V-65,W-5,P-30 1.04 0.08 0.50 1.63 196

FRF 5, GPM DPR, 1.2 MHz (0.6, 0.6)

CFD (V-68,W- 2.55 0.19 0.95 3.68 442 5,P-27)

V-5,W-5,P-90 0.12 0.12 2.14 2.37 283

V-25,W-5,P-70 0.67 0.13 1.87 2.67 321

V-45,W-5,P-50 1.37 0.15 1.53 3.05 367

V-65,W-5,P-30 2.31 0.18 1.07 3.56 425

The results of the parametric studies can be found below in Table 8-23. Rep. ITU-R S.2365-0 89

TABLE 8-23 Results with variance of Frequency Reuse Factor, e.i.r.p. and Transmission type

Precipitation Radar GPM Scatterometer RapidScat Altimeter JASON-2 DPR

% of time dB exceedance % of time dB exceedance % of time dB exceedance exceedance of of 1% exceedance of of 1% exceedance of of .2% –3 dB availability –5 dB availability –10dB availability

FRF x 1.2 e.i.r.p. Median CFD 0.32% –9.6 0.55% –8 0.14% –11.9 V-5,W-5,P-90 0.19% –11.3 0.16% –15.7 0.13% 12.3 V-25,W-5,P-70 0.19% –11.1 0.22% –14.3 0.12% –12.8 V-45,W-5,P-50 0.27% –10.7 0.22% –14.4 0.13% –12.2 V-65,W-5,P-30 0.25% –10.6 0.22% –14.1 0.15% –11.5 e.i.r.p. 1 sigma CFD 0.53% –6 1.13% –4.4 0.27% –8.4 V-5,W-5,P-90 0.36% –7.6 0.29% –11.9 0.27% –8.5 V-25,W-5,P-70 0.36% –7.4 0.41% –10.6 0.24% –9.1 V-45,W-5,P-50 0.44% –7.1 0.38% –10.7 0.27% –8.5 v-65,W-5,P-30 0.49% –7.1 0.40% –10.6 0.30% –7.9 e.i.r.p. 2 sigma

CFD 0.77% –4.2 1.37% –3.6 0.40% –6.4 V-5,W-5,P-90 0.86% –3.8 0.50% –9 0.45% –5.7 V-25,W-5,P-70 0.83% –3.8 0.62% –7.9 0.37% –6.8 V-45,W-5,P-50 0.80% –4.1 0.55% –8.5 0.43% –6.2 v-65,W-5,P-30 0.74% –4.4 0.55% –8.6 0.43% –6.1 FRF x 2 e.i.r.p. Median

CFD 0.63% –6 0.30% –7.3 V-5,W-5,P-90 0.36% –8.8 0.34% –11.6 0.22% –9.4 V-25,W-5,P-70 0.41% –7.8 0.44% –10.3 0.23% –9.3 V-45,W-5,P-50 0.46% –7.1 0.40% –10.7 0.27% –8.2 v-65,W-5,P-30 0.58% –5.8 0.43% –10.4 0.30% –7.3

90 Rep. ITU-R S.2365-0

TABLE 8-23 (continued)

Precipitation Radar GPM Scatterometer RapidScat Altimeter JASON-2 DPR

% of time dB exceedance % of time dB exceedance % of time dB exceedance exceedance of of 1% exceedance of of 1% exceedance of of .2% –3 dB availability –5 dB availability –10dB availability e.i.r.p. 1 sigma

CFD 1.15% –2.4 0.60% –3.6 V-5,W-5,P-90 0.69% –5.1 0.63% –7.9 0.47% –5.7 V-25,W-5,P-70 0.8% –4.1 0.79% –6.6 0.45% –5.5 V-45,W-5,P-50 0.92% –3.5 0.70% –7.1 0.55% –4.4 v-65,W-5,P-30 1.1% –2.3 0.72% –6.9 0.61% –3.6 e.i.r.p. 2 sigma

CFD 1.73% –0.3 0.83% –2 V-5,W-5,P-90 1.62% –1.2 0.97% –5.2 0.82% –2.6 V-25,W-5,P-70 1.74% –0.8 1.17% –4 0.70% –3.3 V-45,W-5,P-50 1.74% –0.6 1.06% –4.7 0.80% –2.4 v-65,W-5,P-30 1.77% –0.3-4 1.00% –5 0.87% –1.5 FRF x 3 e.i.r.p. Median

CFD 0.91% –3.4 0.44% –3.9 V-5,W-5,P-90 0.59% –6.5 0.50% –9.2 0.34% –7.1 V-25,W-5,P-70 0.64% –5.7 0.58% –8.2 0.39% –6.1 V-45,W-5,P-50 0.74% –4.9 0.54% –8.7 0.39% –5.8 V-65,W-5,P-30 0.86% –4 0.74% –7.1 0.41% –4.5 e.i.r.p. 1 sigma

CFD 1.59% 0.1 0.89% –0.3 V-5,W-5,P-90 1.06% –2.7 0.93% –5.4 0.69% –3.3 V-25,W-5,P-70 1.17% –1.9 1.09% –4.5 0.81% –2.4 V-45,W-5,P-50 1.35% –1.3 0.98% –5.1 0.81% –2.1 V-65,W-5,P-30 1.58% –0.5 1.29% –3.5 0.86% –0.9 e.i.r.p. 2 sigma

CFD 2.49% 1.8 1.24% 1.4 V-5,W-5,P-90 2.72% 1 1.51% –2.5 1.16% –0.8 V-25,W-5,P-70 2.63% 1.2 1.72% –1.8 1.33% 0.3 V-45,W-5,P-50 2.68% 1.3 1.43% –3 1.23% –0.2 V-65,W-5,P-30 2.5% 1.5 1.74% –1.7 1.24% 0.90 Rep. ITU-R S.2365-0 91

TABLE 8-23 (continued)

Precipitation Radar GPM Scatterometer RapidScat Altimeter JASON-2 DPR

% of time dB exceedance % of time dB exceedance % of time dB exceedance exceedance of of 1% exceedance of of 1% exceedance of of .2% –3 dB availability –5 dB availability –10dB availability

FRF x 4 e.i.r.p. Median

CFD 1.25% –1.9 0.59% –1.4 V-5,W-5,P-90 0.77% –4.4 0.68% –7.4 0.49% –5.1 V-25,W-5,P-70 0.74% –4.4 0.74% –6.9 0.48% –4.9 V-45,W-5,P-50 0.96% –3.2 0.80% –6.5 0.55% –3.4 V-65,W-5,P-30 1.16% –2.2 0.90% –5.8 0.60% –2.6 e.i.r.p. 1 sigma

CFD 2.26 1.7 1.23% 2.3 V-5,W-5,P-90 1.48% –0.7 1.25% –3.6 1.05% –1.3 V-25,W-5,P-70 1.57% –0.7 1.35% –3.2 1 –1.2 V-45,W-5,P-50 1.83% 0.5 1.43% –2.8 1.17% 0.2 V-65,W-5,P-30 2.1% 1.4 1.54% –2.2 1.28% 1 e.i.r.p. 2 sigma

CFD 3.54% 3.2 1.70% 3.5 V-5,W-5,P-90 3.68% 2.6 1.94% –1 1.78% 1.3 V-25,W-5,P-70 3.55% 2.1 2.10% –0.5 1.55% 1.1 V-45,W-5,P-50 3.66% 2.8 2.14% –0.4 1.78% 2.2 V-65,W-5,P-30 3.33% 3 2.09% –0.3 1.87% 3 FRF x 5 e.i.r.p. Median CFD 1.42% –1 2.59% 3.2 1.23% –1.8 V-5,W-5,P-90 0.94% –3.4 1.20% –2 0.50% –6.9 V-25,W-5,P-70 1.04% –2.7 1.50% –0.7 0.65% –5.4 V-45,W-5,P-50 1.20% –2 1.88% 1 0.80% –4.2 V-65,W-5,P-30 1.43% –0.8 2.20% 2.3 1.00% –2.8 e.i.r.p. 1 sigma CFD 2.69% 2.6 6.46% 6.7 2.28% 1.5 V-5,W-5,P-90 1.80% 0.4 2.60% 1.8 0.90% –3.4 V-25,W-5,P-70 1.97% 1 3.30% 2.9 1.30% –1.9 V-45,W-5,P-50 2.19% 1.7 3.90% 4.7 1.59% –0.8 V-65,W-5,P-30 2.57% 2.8 4.70% 5.8 2.00% 0.6

92 Rep. ITU-R S.2365-0

TABLE 8-23 (end)

Precipitation Radar GPM Scatterometer RapidScat Altimeter JASON-2 DPR

dB dB % of time dB exceedance % of time exceedance % of time exceedance exceedance of of 1% exceedance of 1% exceedance of .2% –3 dB availability of –5 dB availability of –10dB availability

e.i.r.p. 2 sigma CFD 4.29% 4.3 11.61% 8.3 3.90% 4.1 V-5,W-5,P-90 4.70% 3.5 6.80% 4.8 2.13% 1.4 V-25,W-5,P-70 4.51% 3.6 7.50% 5.6 2.70% 2.1 V-45,W-5,P-50 4.34% 3.9 8.40% 6.8 3.00% 2.3 V-65,W-5,P-30 4.29% 4.5 9.50% 7.7 3.50% 3.2

Tables 8-24 and 8-25 provides the number of earth stations used and results of a parametric assessment of the FSS distribution using a uniform versus 60% city centric distribution. The FRF was held constant at 1.2 and the FSS transmission type deployment percentage was held constant as well using the current FSS deployment reported in Report ITU-R S.2364. The analysis providing the results of Table 8-25 used the assumption that the entire FSS deployment of ESs was single continuous transmission carrier. The FSS deployment numbers used to produce the simulation results are contained above. The uniform distribution is based on a distribution of ESs evenly spread over the global land masses from 65 degrees North latitude to 50 degrees South latitude. The 60% city centric distribution takes 60% of the ES numbers and distributes them according to the methodology described in Report ITU-R S.2364. The remaining 40% are distributed uniformly over the global land masses as previously described in this paragraph. The e.i.r.p. of the earth stations in the simulated deployments were varied using the median e.i.r.p. reported by two FSS operators, a 1-sigma increase of e.i.r.p., and a 2-sigma increase in e.i.r.p. These were calculated from the e.i.r.p. cumulative graphs provided by the two FSS operators which are documented in Report ITU-R S.2364. The e.i.r.p. values used in the simulations can be found in Table 8-21 above.

TABLE 8-24 FSS Earth Station Deployment numbers for city centric/uniform distribution

VSAT

spacing

Wideband

per 120 FSS per 120 FSS

satellite per FSS

satellites 3 degree 3 degree satellites FRF 1.2, JASON-3, 250 MHz CFD (V-68,W-5,P-27) 127 9 50 186 11160 Rep. ITU-R S.2365-0 93

TABLE 8-25 Uniform vs 60% City Centric

Precipitation Radar Scatterometer RapidScat Altimeter JASON-3 GPM DPR protection protection protection 1% 1% .2% criteria criteria criteria availability availability availability threshold threshold threshold FRF x 1.2 e.i.r.p. Median F(V,W,P) = CDF Uniform 0.32% –9.6 0.22% –14.10 0.00 –11.50 City-60%, 0.20% –10.7 0.25% –14.20 0.11% –13.50 Uniform-40% e.i.r.p. 1 sigma F(V,W,P) = CDF Uniform 0.53% –4.2 0.40% –10.60 0.30% –7.90 City-60%, 0.42% –7.2 0.43% –10.50 0.21% –9.80 Uniform-40% e.i.r.p. 2 sigma F(V,W,P) = CDF Uniform 0.63% –6 0.55% –8.60 0.43% –6.10 City-60%, 0.59% –5.4 0.65% –7.70 0.26% –8.60 Uniform-40%

8.2.1.11.2.7 FSS TDMA Network impact assessment One of the assumptions used in the study results reported above is that a single network of FSS TDMA ESs can be represented in compatibility simulation analyses by a single continuous transmission ES. This assumption can underrepresent the amount of performance degradation that would impact EESS (active) sensor operation. In the case of JASON-3, the receiver samples the peak power of 100 radar echoes in a 50-millisecond period. The average of the 100 radar echo power peaks for each 50-millisecond period is transmitted to the ground for further processing. In the case of JASON-3, a single TDMA burst of 10 milliseconds with an I/N of ‒3dB received by JASON-3 would result in exceeding the allowable performance degradation threshold of 4% as set forth in Recommendation ITU-R RS.1166-4 for that 50 millisecond. Therefore, in assessing compatibility with another service, the data availability of JASON-3 simulations were performed to determine the percentage of the 50 millisecond samples that are impacted by TDMA bursts which singly or aggregately exceed the ‒3 dB I/N threshold during that 50 millisecond period. The FSS TDMA network characteristics (VSAT, Wideband, and Point-to-Point) used in the simulations are documented in § 8.2.1.11.2.1. The analyses were performed with an FRF of 1.2 and the FSS transmission type deployment percentage of the current FSS deployment reported in Report ITU-R S.2364. The FSS distribution was varied between a uniform and 60% city centric distribution. The uniform distribution is based on a distribution of ESs evenly spread over the global land masses from

94 Rep. ITU-R S.2365-0

65 degrees North latitude to 50 degrees South latitude. The 60% city centric distribution takes 60% of the ES numbers and distributes them according to the methodology described in Report ITU-R S.2364. The remaining 40% are distributed uniformly over the global land masses as previously described in this paragraph. Table 8-26 and Fig. 8-34 provides the number of earth stations and the results for the impact of a 100% TDMA deployment across the three transmission types for a simulation evaluating the impact of assuming the use of a continuously transmitting earth station to represent a single TDMA network in regards to compatibility with JASON-3 operations. Table 8-27 and Fig. 35 provides the number of earth stations and the results for the impact of a 100% TDMA deployment for the VSAT transmission type and continuous transmitting earth stations for the Wideband and Point-to-Point transmission types again in regards to JASON-3 operations. Table 8-28 provides a comparison of the two TDMA simulations against the simulation reported in Table 8-22 using the simplifying assumption of replacing each TDMA network in the simulation with a single continuously transmitting earth station. The results of the comparison indicate the use of the simplifying assumption may underrepresent the interference to the EESS (active) altimeter. The Median e.i.r.p. value, 1-sigma and the 2-sigma e.i.r.p. values for the three transmission types were used. These were calculated from the e.i.r.p. cumulative graphs provided by the two FSS operators which are documented in Report ITU-R S.2364. The bandwidth of the victim receiver was set at 250 MHz corresponding to the bandwidth being sought under WRC-15 agenda item 1.6.2. The time step of the simulation was 10 milliseconds corresponding to the TDMA burst rate of the VSAT transmission type. A uniform landmass distribution of the FSS deployment model between +65 degrees North latitude and –50 degrees South latitude was used in the simulation. After the FSS deployment distribution was created only the VSATs lying between +40 degrees North latitude and –40 degrees South latitude were included in the simulation for the 100% TDMA simulation of all three transmission types. For the simulation examining the 100% TDMA deployment for the VSAT transmission type and continuous transmitting earth stations for the Wideband and Point-to-Point transmission types the VSATs lying between 20 degrees North/South latitude were included in the simulation. This reduction of earth stations reduced the number of ESs in the simulation and hence reduced the computation time necessary for the simulation. Adding in earth stations higher in latitude were found to only marginally worsen the compatibility results. Adding in the remaining VSAT ESs into the simulation would worsen the compatibility results. The Wideband and Point-to-point transmission types were included over the full range from +65 degrees North latitude to –50 degrees South latitude. The higher power of the Wideband and Point-to-Point earth stations were found to exceed the EESS (active) altimeter I/N protection criteria threshold regardless of their deployment over the range of latitudes studied. Rep. ITU-R S.2365-0 95

TABLE 8-26 FSS Earth Station Deployment: 100% TDMA

VSAT

spacing

Wideband

per 120 FSS per 120 FSS

per FSS satellite per FSS 3 degree satellites FRF 1.2, JASON-3, 250 MHz CFD (V-68,W-5,P-27) 3,175 99 550 3,824 458,880

FIGURE 8-34 Results of 100% TDMA Network, JASON-3, FRF 1.2 (all transmission types)

TABLE 8-27 FSS Earth Station Deployment: 100% VSAT TDMA, 0% TDMA for Wideband and Point-Point

VSAT

Wideband

per FSS satellite per FSS spacing 3 degree

per 120 FSS satellites satellites per 120 FSS FRF 1.2, JASON-3, 250 MHz CFD (V-68,W-5,P-27) 3,175 9 50 3,234 388,080

96 Rep. ITU-R S.2365-0

FIGURE 8-35 Results of 100% VSAT TDMA Network, 0% TDMA for Wideband and Point-to-Point, FRF 1.2, JASON-3

TABLE 8-28 Comparison of TDMA simulation versus use of continuously transmitting assumption

–3 dB 1% Exceedance Median +1 STD +2 STD Median +1 STD +2 STD 100% All ES TDMA 0.81% 1.32% 1.68% –4.6 –0.90 0.50 100% VSAT 0% PT2PT, Wideband TDMA 0.61% 0.98% 1.26% –6.60 –3.20 –1.20 All continuous transmitting ES 0.32% 0.53% 0.77% –9.60 –6.00 –4.20

8.2.1.11.2.8 Summary of sharing analysis #4 With the assumptions described in Sharing analysis #4, provided herein are the results of simulations examining the impact to three representative EESS(active) sensors (JASON-3, RapidScat, and GPM DPR) from the emissions of potential FSS deployments of earth stations using the FSS deployment model information provided in Report ITU-R S.2364. Three separate sets of simulations were produced 1) parametric studies varying FRF from 1.2 to 5, 2) assessment of FSS deployment using a uniform distribution versus a city centric distribution, 3) assessment of the simplifying assumption of using a single continuously transmitting earth station in place of a TDMA network. The parametric series of simulations were conducted varying the FSS GSO frequency reuse factor from an FRF of 1.2 to 5. The parametric studies also examined varying the FSS deployment transmission types by percentage of transmissions as described above. In addition, studies were conducted with e.i.r.p. of the FSS earth stations, as reported in Report ITU-R S.2364, at the average of the peak envelope power level, the +1 sigma level, and the +2 sigma level. The results of this simulation set are provided in Table 8-23. The results indicate that starting at the range of an FRF of 3 (1-sigma e.i.r.p. level), that compatibility will fail the Recommendation ITU-R RS.1166-4 random data availability criteria of 1% for the JASON-3 sensor. Rep. ITU-R S.2365-0 97

Table 8-25 provides the results of the assessment of FSS deployment of FRF 1.2, using a uniform distribution versus a city centric distribution. The results indicate that the difference in results between using a uniform or city centric deployment is slight. Figure 8-34 provides the results examining a 100% TDMA network across all three transmission types using a FSS deployment of FRF 1.2. This was performed examining the interference impact on JASON-3. Figure 8-35 provides the results examining a 100% VSAT TDMA network deployment along with 0% TDMA network deployment for the Wideband and Point-to-point transmission types (that is, the Wideband and Point-to-point transmission types were simulated as single continuously transmitting earth stations instead of multiple bursting TDMA earth stations). The comparison of these results with those of Table 8-25, for a simulation (JASON-3, FRF 1.2) that has no TDMA network representation, shows that the assumption of using a single continuously transmitting earth station in place of a TDMA network underestimates the amount of interference seen by the sensor. Table 8-28 provides a summary of the differences.

8.2.1.11.3 Sharing analysis #5 – Dynamic analysis Concerning EESS (active) systems, it is noted that the percentage of time associated with the protection criterion is 1% for the altimeter and scatterometer (systematic interference), and 0.2% for the precipitation radar, according to Recommendation ITU-R RS.1166-4.

8.2.1.11.3.1 Simulation for the SENTINEL-3 altimeter According to the deployment model used, 21 360 FSS Earth stations have been deployed worldwide in a frequency band of 250 MHz (see Table-8-29 and Fig. 8-36), with a distribution depending on the population density. It should be noted that the deployment model allows for FSS stations to be also deployed in areas where there is few to no population. In this case the probability to find an FSS Earth station is simply much lower. Each FSS Earth station is pointing to one GSO satellite chosen randomly between a total of 120 GSO satellites, one each 3 degrees, provided that a minimum elevation angle of 10° is respected.

FIGURE 8-36 Location of the 21 360 FSS Earth stations

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TABLE 8-29 Number of FSS Earth stations used in simulations for altimeters

Number of Number of Number of Transmissions Transmission Percentage of Total Transmissions in Transmissions in in 250 MHz Type Satellite Transmissions 250 MHz per 500 MHz per satellite for 120 satellite satellites VSAT 69.30% 246 123 14760 Wideband 4.90% 17 9 1080 Point-to-Point 25.80% 92 46 5520 All 100% 355 178 21360

For each transmission type, the antenna diameter and power spectral density of the Earth station is randomly chosen assuming a Gaussian distribution with the average and standard deviation values as contained in Table 4-2. Similarly, the bandwidth is randomly chosen following the cumulative distributions provided in Report ITU-R S.2364. The emission power is then the DSP multiplied by the bandwidth. The overall distributions obtained are shown in Figs 8-37 to 8-39.

FIGURE 8-37 FSS ES antenna diameter

Rep. ITU-R S.2365-0 99

FIGURE 8-38 FSS ES emission bandwidth

FIGURE 8-39 FSS ES emission power

The Sentinel-3 orbits are simulated during 27 days with a time step of 1 second. The antenna pattern used is based on existing measurements of the SRAL antenna pattern which will be used on board SENTINEL-3. It should be noted that compared to Recommendation ITU-R F.1245 which is traditionally used in sharing studies, including outside FS, the measurements exhibit higher average side-lobe levels in the far side lobes, and lower first side lobe levels. It should be noted that the altimeter SRAL will acquire topography data over all types of surfaces covered by the Sentinel-3 mission (sea, coastal areas, sea ice, ice sheets, ice margins, in-land waters). SRAL will provide measurements with a high spatial resolution (~300 m along-track) over specific dynamic ocean regions, coastal regions (up to 300 km offshore), sea-ice and inland areas. The measurements are therefore not limited to oceans.

100 Rep. ITU-R S.2365-0

FIGURE 8-40 Cdf of interference received on SENTINEL-3

As shown in Fig. 8-40, the 21 360 FSS earth stations create an interference level of –127.6 dBW for 1% of the time in SENTINEL-3 SRAL receiver, therefore not exceeding the protection criterion of –116 dBW/350 MHz with a positive margin of about 11 dB.

8.2.1.11.3.2 Simulation for the QuikSCAT scatterometer The scatterometer bandwidth has been assumed to be 0.6 MHz. Therefore, as we considered 120 GSO satellites, one each 3 degrees, with a frequency reuse factor of 1.2, 144 (120  1.2) FSS Earth stations (number of GSO satellite  frequency reuse factor) have been deployed worldwide (see Table 8-30 and Fig. 8-41). Each FSS Earth station is pointing to one GSO satellite chosen randomly between a total of 120 GSO satellites, one each 3 degrees, provided that a minimum elevation angle of 10° is respected. The same repartition of antennas deployed in 500 MHz observed in Table 8-30 is used to assess the number of each type of antenna in 0.6 MHz. Rep. ITU-R S.2365-0 101

FIGURE 8-41 Location of the 144 FSS Earth stations

TABLE 8-30 FSS antenna characteristics used in simulations for scatterometer

Number of Number of Number of Percentage of Total Transmission Transmissions in Transmissions in Transmissions in Satellite Type 500 MHz per EESS bandwidth EESS bandwidth Transmissions satellite per satellite for 120 satellites VSAT 69.30% 246 0 to 1 100 Wideband 4.90% 17 0 to 1 7 Point-to-Point 25.80% 92 0 to 1 37 All 100% 355 1.2 144

The QuikSCAT orbits are simulated during 1 day with a time step of 0.1 second.

102 Rep. ITU-R S.2365-0

FIGURE 8-42 Cdf of interference received on QuikSCAT generated by all antennas as defined

As shown in Fig. 8-42, the 144 FSS earth stations create an interference level of –155.7 dBW for 1% of the time, therefore not exceeding the protection criterion with a positive margin of about 20 dB.

8.2.1.11.3.3 Summary of sharing analysis #5 Considering the number of FSS earth stations deployed worldwide that was based on the deployment model given in § 4, the dynamic simulations presented in this Report depict situations where the EESS (active) protection criteria is always met for all kinds of sensors considered, with a positive margin ranging from 10 to 20 dB.

8.2.1.11.4 Sharing analysis #6 – Dynamic analysis 8.2.1.11.4.1 Simulations for the JASON-3 altimeter According to the deployment model used and a frequency reuse factor of 1.2, 6480 (= 120*54) FSS Earth stations have been deployed worldwide in a frequency band of 250 MHz (see Table 8-31 and Fig. 8-43). Each FSS Earth station is pointing to one GSO satellite between a total of 120 GSO satellites, one each 3 degrees. This total number of FSS earth stations is valid for one polarization. As explained in the deployment model, as all FSS satellites operate using two polarizations, the overall results in terms of received power on board the altimeter will be increased by 3 dB, and therefore valid for a total of 12960 FSS earth stations. Rep. ITU-R S.2365-0 103

FIGURE 8-43 Location of the 6480 FSS Earth stations

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TABLE 8-31 FSS deployment model for one polarization

1 polarization 1 GSO Transponder 250 bandwidth MHz Number polar 1

Station Classification Typical Maximum power Standard Number of carrier channel % of spectrum Earth type antenna antenna spectral density deviation stations BW bandwidth usage diameter (m) size/gain dBW/Hz of input power FSS1 MHz

1.2 m/43.5 VSAT <= 3 dBi –42 4.00 33 0.5 13.20% Wideband > 3 3.3 m/52 dBi –49 2.10 2 28.3 43.00% 3.9 m/53.5 Point to Point dBi –50 2.40 19 2.9 43.80%

54 100.00%

Rep. ITU-R S.2365-0 105

Following the explanation regarding the JASON operation, only peak powers are considered.

FIGURE 8-44 Cdf of interference received on JASON on a worldwide basis

2 10

1 10

0 10

-1 10

Corresponding cumulative % Corresponding -2 10

-3 10 -260 -240 -220 -200 -180 -160 -140 -120 Received power at the altimeter

As shown in Fig. 8-44 (the bandwidth unit is the MHz), the 6 480 FSS earth stations create an interference level of –152 dBW/MHz 1% of the time. As the sensitivity threshold is –146 dBW, we have a 6 dB positive margin with one polarization. With two polarizations, we have a 3 dB positive margin. Taking into account multi Ku-band steerable spot beams technology (overall capacity to be increased up to 7 dB), the resulting margin is –4 dB and compatibility is not ensured on the long term. Figure 8-44 is based on statistics on a worldwide basis. However, JASON has a revisit time of 10 days. As outlined in this report, altimeters and scatterometers are concerned by cases where RFI occur in a systematic way at the same location. Should the losses of sensing data occur systematically at the same locations (since FSS earth stations are fixed by nature), these areas would never be observed which will unduly constrain the success of any EESS (active) space mission. Recommendation ITU-R RS.1166 protection criteria is valid in the corresponding area of interest and prescribes 99% data availability, which is equivalent to 99% of the time for all areas of measurement of interest. The following Figure illustrates this case where around a given location (for instance 27 N, –88 E, but it could be placed in other sea/land/wet area, similar results would be provided), statistics are shown only within a circle of 2 000 km for example.

106 Rep. ITU-R S.2365-0

FIGURE 8-45 Cdf of interference received on JASON around a specific location (27 N, –88 E)

2 10

1 10

0 10

Corresponding cumulative % Corresponding

-1 10 -190 -185 -180 -175 -170 -165 -160 -155 -150 -145 -140 Received power at the altimeter

As shown in Fig. 8-45, the 6480 FSS earth stations create an interference level of –144 dBW/MHz 1% of the time: it exceeds the sensitivity threshold is –146 dBW for one polarization. With two polarizations, we have a –5 dB negative margin. Taking into account multi Ku-band steerable spot beams technology (overall capacity to be increased up to 7 dB), the resulting margin is –12 dB. Therefore, in specific areas smaller than the whole world, compatibility is not ensured.

8.2.1.11.4.2 Summary of sharing analysis #6 Considering a realistic number of FSS earth stations deployed worldwide, the dynamic simulations presented in this Report depict situations showing compatibility (with small margins) with EESS (active) based on statistics on a worldwide basis. Should multi Ku-band spot beams technology is used, compatibility is no longer ensured. In addition, should specific areas (sea/land/wet areas) of the world are observed, instead of a worldwide basis, both services are not compatible showing higher negative margins.

8.2.1.11.5 Sharing analysis #7 – Dynamic analysis 8.2.1.11.5.1 Approach to sharing analysis #7 Simulations in these dynamic analyses were performed using two different scenarios. In the 1st simulation scenario (named specific ES parameters deployment scenario), specific parameters (i.e. type of FSS Earth Station, antenna size, transmit power density and transmit carrier bandwidth) were individually allocated to each FSS Earth Station deployed for the simulation. In the 2nd simulation scenario (named identical ES parameters deployment scenario), the same parameters were allocated to all FSS Earth Station deployed for the simulation. The goal of this 2nd simulation scenario, is to assess the potential level of Interference from a specific ES on all types of active sensors used in the EESS (active). Based on these simulation results, some possible limitation on the parameters of the Earth Station could be proposed to ensure a compatibility with EESS (active).

8.2.1.11.5.2 FSS (E-s) allocation strategy & deployment model In these simulations, it was considered that 50% of the transmit Earth stations are distributed on a uniform worldwide basis and the remaining 50% are distributed on a population density basis. Rep. ITU-R S.2365-0 107

The number of total stations in the simulation was obtained by considering, as a starting point, the statistics of the model (i.e. % of total bandwidth for each type of antenna and occupied bandwidth for each type of antenna) in order to reach the total amount of spectrum used by satellites in this simulation (i.e. 36 000 MHz = 250 MHz  1.2  120 satellites) (single polarization considered). In these simulations, it was considered that the carrier bandwidth distribution of the FSS deployment model provided in § 4 of this Report was the Nyquist bandwidth carrier. And therefore, a roll-off factor of 20% was applied to obtain the occupied bandwidth of each carrier. After further verification, it was highlighted that the carrier bandwidth distribution of the FSS deployment model provided in § 4 of this Report was the occupied bandwidth carrier, therefore the roll-off factor of 20% was not required. Therefore, the number of Earth stations used in these studies is underestimated When the interference from FSS (E-s) is computed in a bandwidth greater than 250 MHz (e.g. altimeter), it is unrealistic to consider that all FSS satellites have a unique transponder bandwidth of 125 MHz or 250 MHz. In practice, transponder bandwidth of FSS satellites is typically equal to 26 MHz, 36 MHz, 54 MHz or 72 MHz. Due to necessary required guard band between transponders to avoid harmful interference, the amount of available spectrum for FSS (E-s) in the NGSO study bandwidth of 125 MHz or 250 MHz is less than 125 MHz or 250 MHz. For example, if we consider a NGSO study bandwidth of 250 MHz, we could have maximum 8 transponders of 26 MHz bandwidth or 6 transponders of 36 MHz bandwidth or 4 transponders of 54 MHz bandwidth or 3 transponders of 72 MHz bandwidth.

TABLE 8-32 Percentage bandwidth available for FSS satellites

Ratio bandwidth Max. bandwidth FSS transponders Max. number of available on FSS available on FSS bandwidth transponders in a band satellite Vs total satellite (MHz) of 250 MHz bandwidth of (MHz) 250 MHz 26 8 208 83% 36 6 216 86% 54 4 216 86% 72 3 216 86%

To not underestimate the number of potential FSS (E-s) emission, a value of 90% was considered in these simulations as percentage bandwidth available for FSS satellites in these simulations with a NGSO study bandwidth of 125 MHz or greater than 250 MHz. It should be noted that when the average earth station characteristics of the model contained in Report ITU-R S.2364, derived from the combined deployment data of two FSS operators, that a global deployment of 10,650 earths stations is found. The deployment model in Report ITU-R S.2364 provides information on the number of GSO FSS transmissions per satellite, their average characteristics, and parameter deviation distribution information, over the entire 14-14.5 GHz allocated band that is being used as a proxy for studies in this band. Guardbands between carriers and transponders are inherently accounted for in deployment model in Report ITU-R S.2364 earth station parameters; that is, when the average bandwidths are used there is unused bandwidth corresponding to the individual carrier and transponder guardbands when also taking into account the current FSS GSO FRF in 14-14.5 GHz. Deviating from using the average bandwidth per transmission type of the model in Report ITU-R S.2364 would require adjusting the number of transmissions for the transmission types affected.

108 Rep. ITU-R S.2365-0

8.2.1.11.5.3 EESS (active) characteristics used for sharing analysis #7 The EESS (active) characteristics used in these studies are summarized in Table 8-33 for 3 different types of sensors.

TABLE 8-33 Characteristics of current flying spaceborne active sensors in the 13.25-13.75 GHz band

Parameters Active sensor type and mission Altimeter Scatterometer JASON-1/2/3 QuikSCAT Seawinds SENTINEL-3 Orbit altitude, km 1 336 (JASON) 803 815 (SENTINEL-3) Orbit inclination, deg 66 (JASON) 98.2 98 (SENTINEL-3) Antenna type 1.2 m diameter parabolic dish 1 m diameter parabolic dish Antenna polarization Linear Horizontal (inner), Vertical (outer) Antenna peak gain, dBi 43.9 41.0 Antenna elevation 1.28 1.6 (inner), beamwidth, deg 1.4 (outer) Antenna azimuth beamwidth, deg 1.28 1.8 (inner), 1.7 (outer) Antenna beam look angle, deg 0 40 (inner), 46 (outer) Antenna scan range, deg 0 0 to 360 Antenna scan period, sec 0 3.33 (18 rpm) Antenna pointing Fixed at nadir Circular scanning in azimuth Centre RF frequency, GHz 13.575 GHz and 13.285 GHz 13.402 (JASON) 13.575 GHz (SENTINEL-3) Receiver bandwidth, MHz 320 to 350 0.40 Protection criterion –142 dBW/MHz –195 dBW/Hz or –135 dBW/MHz Comments Nadir looking Rotating dish antenna with two spot beams sweeping a circular pattern. QuikSCAT has 4 look angles and the resolution in conical scan mode is 50 km.

The percentage of time associated with the protection criterion is 1% for the altimeter and scatterometer (systematic interference), and 0.2% for the precipitation radar, according to Recommendation ITU-R RS.1166-4. Rep. ITU-R S.2365-0 109

8.2.1.11.5.4 Simulations for altimeters SENTINEL-3 and JASON-3 8.2.1.11.5.4.1 Cumulative analysis with specific ES parameters deployment scenario In this simulation, 8 142 FSS Earth stations have been deployed worldwide (50% according to population density & 50% according to uniform distribution) in a frequency band of 250 MHz (see Table 8-34). Each FSS Earth station is pointing to one GSO satellite chosen randomly between a total of 120 GSO satellites, one each 3 degrees, provided that a minimum elevation angle of 10° is respected.

TABLE 8-34 FSS antenna characteristics used in simulations for altimeters (specific ES parameters deployment scenario)

The SENTINEL-3 and JASON orbits are simulated during 27 days with a time step of 1 minute. The antenna patterns used for JASON and SENTINEL-3 is based on existing measurement of the SRAL antenna pattern. As shown in Fig. 8-46, the 8 142 FSS Earth stations create an interference level of –135.5 dBW for 1% of the time in SENTINEL-3 SRAL receiver and –134 dBW for 1% of the time in JASON SRAL receiver, therefore not exceeding the protection criterion of –117 dBW/320 MHz with a positive margin of about 17 dB.

FIGURE 8-46 Cdf of interference received on SENTINEL-3 & JASON-3 (specific ES characteristics deployment scenario)

110 Rep. ITU-R S.2365-0

8.2.1.11.5.4.2 Cumulative analysis with identical ES parameters deployment scenario Despite the fact it is unlikely to observe following scenarios, simulations performed under section above were reproduced considering that all FSS (E-s) terminal will be only 60 cm VSAT terminals with the maximum power spectral density as defined for single entry calculation reproduced in § 4 of this Report (i.e. –42 dBW/Hz). Considering an earth station carrier bandwidth of 600 kHz, 45 000 FSS earth stations have been deployed worldwide (50% according to population density & 50% according to uniform distribution) in a frequency band of 250 MHz. Each FSS earth station is pointing to one GSO satellite chosen randomly between a total of 120 GSO satellites, one each 3 degrees, provided that a minimum elevation angle of 10 degrees is respected. The SENTINEL-3 and JASON orbits are simulated during 27 days with a time step of 1 minute. Figure 8-47 contains results of these simulations with 45 000 FSS earth stations. As shown in Fig. 8-47, the 45 000 FSS earth stations with an antenna diameter of 60 cm create an interference level of –117.5 dBW for 1% of the time in SENTINEL-3 SRAL receiver and –118.5 dBW for 1% of the time in JASON SRAL receiver, therefore not exceeding the protection criterion of – 117 dBW/320 MHz with a 1 dB positive margin.

FIGURE 8-47 Cdf of interference received on SENTINEL-3 & JASON (identical ES characteristics deployment scenario with 60 cm)

/ SENTINEL-3

8.2.1.11.5.4.3 Summary of altimeter dynamic simulations An overview of results obtained for all simulations is reproduced in Table 8-35 below. Rep. ITU-R S.2365-0 111

TABLE 8-35 Simulations result overview for altimeters

SENTINEL-3 JASON Exceedence Exceedence Interference level margin of Interference level margin of Simulation scenario (dBW/320 MHz) interference (dBW/320 MHz) interference criteria (dB) criteria (dB) Specific ES –135.5 –18.5 –134 –17 characteristics deployment scenario Identical ES –117.5 –0.5 –118.5 –1.5 characteristics deployment scenario with 60 cm and Max. Power

As shown in Table 8-35, a new FSS (E-s) allocation in the band 13.25-13.75 GHz with regard altimeters is compatible considering a FSS (E-s) specific characteristics deployment scenario and is even compatible considering an unlikely deployment scenario with only FSS (E-s) antenna diameter equal to 60 cm with a power spectral density equal to –42 dBW/Hz.

8.2.1.11.5.5 Simulations for the QuikSCAT scatterometer (identical ES characteristics deployment scenario) As the protection criteria and wanted carrier are in a bandwidth of 1 MHz, as the transmit FSS carrier are slightly lower or greater than 1 MHz and as we considering 120 GSO satellites (one each 3 degrees) with a frequency reuse factor of 1.2, these simulations have been performed using 150 FSS Earth stations worldwide deployed (50% according to population density, and 50% according to uniform distribution). Each FSS Earth station is pointing to one GSO satellite chosen randomly between a total of 120 GSO satellites, one each 3 degrees, provided that a minimum elevation angle of 10° is respected. Despite the fact it is unlikely to observe following scenarios, simulations performed in this section considered that all FSS (E-s) terminal will have the same parameters (i.e. type of service, antenna size and power spectral density). Simulations have been performed for each transmission type, different antenna sizes and different power spectral densities without exceeding the maximum transmit e.i.r.p. density as defined for single entry calculation reproduced in § 4 of this Report. An overview of parameters used for each simulation as shown in Table 8-36.

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TABLE 8-36 FSS antenna characteristics used in simulations for scatterometer (identical ES characteristics deployment scenario)

Power spectral Scenario FSS (E-s) Antenna Gain e.i.r.p. Density Diameter (m) density number Type (dBi) (dBW/Hz) (dBW/Hz)

1 –42 –5.3 VSAT 0.6 36.7 7 –50 –13.3 2 VSAT 2.8 49.7 48.2 1.5 3 Wideband 3.2 50.9 –49 1.9 4 Wideband 9.1 59.6 –56.6 3 5 P-t-P 1.3 43.4 –50 –6.6 6 P-t-P 6 56 –52.5 3.5

The QuikSCAT orbits are simulated during 4 days with a time step of 3.33 seconds. The antenna patterns used for QuikSCAT are the same as used for the altimeter. Figures 8-48 and 8-49 contain results of these simulations with 150 FSS Earth stations. As shown in Fig. 8-48, the 150 FSS Earth stations with antenna characteristics according to scenario number 1 (i.e. 60 cm VSAT with Pe = –42 dBW/Hz) create an interference level of –134 dBW for 1% of the time in QuikSCAT receiver, therefore exceeding the protection criterion of –135 dBW/ MHz by a 1 dB positive margin. All other scenarios (i.e. scenario 2 to 6), considering maximum power spectral density for antenna greater than 60 cm, create an interference level between –140.5 dBW and –149 dBW for 1% of the time in QuikSCAT receiver, therefore not exceeding the protection criterion of –135 dBW/ MHz by minimum 5.5 dB and up to 14 dB.

FIGURE 8-48 Cdf of interference received on QuikSCAT generated according scenarios 1 to 6 (identical ES characteristics deployment scenario)

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In order to respect the protection criterion of –135 dBW/ MHz for the 60 cm case, the power density was reducing accordingly (i.e. scenario number 7 as listed in Table 8-36). As shown in Fig. 8-49 below, the 150 FSS Earth stations with reduced power density create now an interference level that exceeds the protection criterion of –135 dBW/ MHz by about 7 dB.

FIGURE 8-49 Cdf of interference received on QuikSCAT generated according scenario 7 (identical ES characteristics deployment scenario)

An overview of results obtained for all simulations is reproduced in Table 8-37 below.

TABLE 8-37 Simulations result overview for scatterometer

QuikSCAT Simulation FSS (E-s) Antenna Power spectral Exceedence of scenario Interference level type diameter (m) density (dBW/Hz) interference criteria number (dBW/MHz) (dB) 1 –42 –134 +1 VSAT 0.6 7 –50 –142 –7 2 VSAT 2.8 –48.2 –140.5 –5.5 3 Wideband 3.2 –49 –141 –6 4 Wideband 9.1 –56.6 –149 –14 5 P-t-P 1.3 –50 –143 –8 6 P-t-P 6 –52.5 –145 –10

As shown in Table 8-37, a new FSS (E-s) allocation in the band 13.25-13.75 GHz with regard to scatterometer is compatible for FSS (E-s) antenna diameter greater than 60 cm with maximum power spectral density as defined for single entry calculation reproduced in § 4 of this Report considering an unlikely deployment scenario with identical characteristics for each Earth station. According to

114 Rep. ITU-R S.2365-0 the excess of interference, compatibility is also verified for a VSAT antenna diameter of 60 cm with a maximum power spectral density greater than or equal to –43 dBW/Hz. An overview of results obtained for all simulations is reproduced in Table 8-38 below.

TABLE 8-38 Simulations result overview for precipitation radar

QuikSCAT Simulation FSS (E-s) Antenna Power spectral Exceedence margin scenario Interference level type diameter (m) density (dBW/Hz) of interference number (dBW/MHz) criteria (dB) 1 –42 –137 +10.8 VSAT 0.6 7 –53 –150 –2.2 2 –48.2 –144.5 +3.3 VSAT 2.8 8 –53 –150 –2.2 3 –49 –145.5 +2.3 Wideband 3.2 9 –53 –150 –2.2 4 Wideband 9.1 –56.6 –153 –5.2 5 –50 –146.5 +1.3 P-t-P 1.3 10 –53 –150 –2.2 6 P-t-P 6 –52.5 –149 –1.2

As shown in Table 8-38, a new FSS (E-s) allocation in the band 13.25-13.75 GHz with regard to precipitation radar is compatible for FSS (E-s) considering some limitation in the maximum power spectral density as defined for single entry calculation reproduced in § 4 of this Report considering an unlikely deployment scenario with identical characteristics for each Earth station. According to the excess of interference, compatibility is verified for all type of FSS (E-s) service with a maximum power spectral density greater than or equal to –50.8 dBW/Hz.

8.2.1.11.5.6 Summary of sharing analysis #7 In this simulation the deployment model developed for use in statistical and dynamic simulations, considering the adequate number of FSS stations deployed worldwide, the dynamic simulations presented in this Report depict situations where the EESS (active) protection criteria protection criteria are never exceeded for all kinds of sensors considered. For unlikely simulations with identical ES parameters for all emissions), using some FSS (E-s) terminal characteristics as defined for single entry calculation reproduced in § 4 of this Report, all dynamic simulations presented in this Report depict situations where the EESS (active) protection criteria are never exceeded for all kinds of sensors considered. This therefore confirms that FSS (E-s) with EESS (active) are compatible subject to some FSS (E-s) parameters restriction. According to the results of these studies, compatibility is achieve for all type of FSS (E-s) services and all antenna diameter with a maximum power spectral density greater than or equal to –50.8 dBW/Hz.

8.2.1.11.6 Sharing analysis #8 – Dynamic analysis Using a single entry type of analysis, a parametric analysis was carried out to determine the impact of a single earth station on an inland measurement area of interest. The three FSS earth station Rep. ITU-R S.2365-0 115 transmission types were considered using the median, 1 STD, and 2 STD transmit power. These were derived from the power spectral density cumulative distribution graphs for the three transmission types defined in Report ITU-R S.2364. In the case of the VSAT, the maximum transmit power was also examined. The FSS ES characteristics used in the studies are summarized in Table 8-39. The size of the measurement area of interest was varied from 10 pixels to 300 pixels in length. The placement of the measurement area of interest was varied from 0 degrees latitude to roughly 45 degrees latitude. For each analysis point, a single FSS earth station of each transmission was situated on the surface of the Earth in a location with its antenna orientation towards a GSO FSS orbital location such that the transmission of the earth station would have the maximum interference impact on the JASON sensor. It should be noted that, that due to the number of GSO orbital positions visible from each potential FSS earth station location, for each measurement area of interest there are a set of FSS earth station locations and antenna pointings that would produce the maximum impact on the JASON receiver. While it is recognized, that coordination is regularly undertaken, between every FSS system with other FSS systems, and for earth stations that are in bands shared with terrestrial services, the number of potential global wide measurement areas of interest with the number of associated FSS earth station placements consistent with the deployment model provided in Report ITU-R S.2364 and antenna pointings that could cause interference in excess of the EESS (active) protection criteria would make coordination unsatisfactory as a solution for avoiding FSS earth station interference to altimeter measurement areas of interest on a global basis. Figures 8-50 through 8-60 provide the results of the parametric studies carried out for the impact that a single FSS earth station could have on the operation of the JASON-2 altimeter taking measurements of inland measurement areas of interest. Each line in the graph traces the –3 dB exceedance for a measurement area of interest ranging from 10 pixels (or footprints) to 300 pixels over a latitude of 0 degrees to about 47 degrees. The vertical axis traces the area in which a FSS earth station of the type and transmission power (and pointing at a FSS GSO slot) can be located in and still produce interference in excess of the systematic interference protection criteria provided for in Recommendation ITU-R RS.1166-4. This area for the placement of the FSS station is for a single earth station pointing at a single GSO slot and the total area where placement of an earth station would cause interference exceeding the systematic protection criteria would be the area reported for a single earth station multiplied by the number of GSO slots visible at the latitude studied.

TABLE 8-39 FSS characteristics used for Area of Interest studies

BW Antenna Median power +1 STD +2 STD Maximum (MHz) size (m) (dBw/Hz) (dBW/Hz) (dBW/Hz) (dBW/Hz) VSAT 0.6 1.2 –9.23 –6 –5.62 –3.62 Wideband 30.8 2.8 –3.4 0.5 –2 0.0 Point-Point 2.94 3.8 –5.62 1 3 7

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FIGURE 8-50 Measurement Area of Interest Parametric Analysis: Wideband Average

FIGURE 8-51 Measurement Area of Interest Parametric Analysis: Wideband 1 STD

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FIGURE 8-52 Measurement Area of Interest Parametric Analysis: Wideband 2 STD

FIGURE 8-53 Measurement Area of Interest Parametric Analysis: VSAT Average

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FIGURE 8-54 Measurement Area of Interest Parametric Analysis: VSAT 1 STD

FIGURE 8-55 Measurement Area of Interest Parametric Analysis: VSAT 2 STD

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FIGURE 8-56 Measurement Area of Interest Parametric Analysis: VSAT Maximum

FIGURE 8-57 Measurement Area of Interest Parametric Analysis: Point-to-Point Average

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FIGURE 8-58 Measurement Area of Interest Parametric Analysis: Point-to-Point 1 STD

FIGURE 8-59 Measurement Area of Interest Parametric Analysis: Point-to-Point 2 STD

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FIGURE 8-60 Measurement Area of Interest Parametric Analysis: Point-to-Point 2 Maximum

The results show that a single VSAT with a power at 1 STD can cause interference in excess of Recommendation ITU-R RS.1166-4 systematic interference protection criteria for measurement areas of interest of any size considered from 10 degrees latitude on the inland surface of the Earth. A single Wideband earth station employing median transmission power can cause interference in excess of Recommendation ITU-R RS.1166-4 systematic interference protection criteria for measurement areas of interest of any size considered from 45 degrees latitude on the inland surface of the Earth. A single Point-to-point of median power cause interference in excess of Recommendation ITU-R RS.1166-4 systematic interference protection criteria for measurement areas of interest of any size considered from 45 degrees latitude on the inland surface of the Earth. The studies show that there is increased sensitivity FSS station interference for measurement areas of interest on the lower end of the scale for measurement area. Aggregate interference scenarios considering multiple FSS earth stations have not been considered in this analysis. The results of this parametric study varying the JASON-2 altimeter inland measurement areas of interest over a range of latitudes indicate that an FSS (E-s) allocation in the 13.25-13.75 GHz band would cause interference to EESS (active) JASON-2 altimeter in excess of the Recommendation ITU-R RS.1166-4 systematic protection criteria over large portions of the Earth.

8.2.1.11.6.1 Sharing analysis #8 – Assessment of coordination as a mitigation technique The indeterminate nature of measurement areas of interest, in addition to the number of different EESS altimeters having different orbital parameters, would make coordination with FSS (Earth-to- space) an unsatisfactory mitigation technique as described in § 8.2.1.11.6. Any FSS (E-s) deployment could adversely affect future systematic data availability of measurement areas of interest from a future EESS sensor. An FSS deployment would result in a large numbers of geographic areas where the Recommendation ITU-R RS.1166-4 protection criteria for systematic data availability would be exceeded.

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In order to protect the EESS (active) measurement areas of interest from unacceptable interference, each FSS earth station would have to be coordinated with each EESS altimeter mission. Another aspect of FSS (E-s) earth station coordination with EESS altimeters that would have to be accounted for would be instances of aggregate FSS (E-s) interference from two or more earth stations that could simultaneously illuminate the same track point. Simulations of global FSS earth station deployments have shown that aggregation of interference from two FSS (E-s) transmissions is not an uncommon occurrence while interference aggregation from three or more earth stations is rather rare. Therefore, in any coordination that would be envisioned, an additional 3 dB should be added to the coordination threshold to account for the aggregation of interference from two earth stations. One method of enacting this coordination would require that the operators of those EESS altimeter missions have knowledge of all the potential measurement areas of interest that could be accessed from the database of their altimeter operations. However, those interest areas are often identified in an ad hoc manner by principal investigators who are not directly associated with the EESS altimeter mission. Additionally, the measurement areas of interest are identified in response to investigations by principal investigators as they arise. As a result of these factors, a complete list of measurement areas of interest that could result from future investigations cannot be exhaustively compiled. A more practical method of coordination would be that of situating the FSS (E-s) earth station transmit beam in such a manner so as to avoid the orbital path of any EESS sensor that is used for measurement areas of interest; i.e. altimeters and scatterometers. Figure 8-61 shows the orbital paths of the JASON, Sentinel, SWIM, and HY-2A repeat orbital paths from the viewpoint of an observer at a distant location away from the Earth. When viewed from the surface of the Earth, the transmit beam of an potentially interfering FSS earth station would need to avoid intersecting any of the orbital paths of this current set of missions in order to avoid degrading the measurement area of interest that the mission would record and archive. From the viewpoint of the FSS earth station, as the antenna elevation angle declined toward the horizon the orbital paths would appear closer together than they do in Fig. 8-61. However, this coordination approach and any other coordination approach would only protect current EESS altimeters; future altimeters having different orbital parameters than the current altimeters would not be protected from earth station deployments whose transmit beams intersected these future EESS altimeters orbital paths. Rep. ITU-R S.2365-0 123

FIGURE 8-61 Orbital paths of JASON, Sentinel, SWIM, and HY-2A over a portion of Region 2

Example Interference Impact on a Measurement Area of Interest Figure 8-62 records the interference impact of a FSS deployment (FRF 1.2, mean PSD) to JASON Altimeter measurements over a specific measurement area of interest; Lake Victoria and its surrounding flood plains in Africa. The JASON altimeter has a resolution of about 200-300 metres. This analysis was conducted with this same 200-300 metre resolution. The results indicate that there will be numerous interference incidents which exceed the systematic data availability protection criteria for the EESS altimeter. These exceedances are indicated by the light turquoise colored spots on the blue background portion of the Lake Victoria close-up in Fig. 8-62 below. These interference event locations shown in Fig. 8-62 occur for sensor measurements obtained within the lake or its flood plains and are not the locations of the earth stations. Aggregate interference events, where overlap of multiple earth station main beam are shown as grey ovals around coupled turquoise colored spots in Fig. 8-62 below. The red line in Fig. 8-62 is an outline of the Lake Victoria coastline. The blue dots on the grey background around Lake Victoria represent the nearby FSS Earth station locations deployed according to the deployment model described in Report ITU-R S.2364. The placement of Lake Victoria within Africa is provided in Fig. 8-62.

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These results indicate that an FSS (E-s) deployment would create a number of interference events exceeding the protection criteria and impact the ability of EESS altimeters to correctly measure and retain records of water levels and flood plains on a global basis.

FIGURE 8-62 JASON Uniform Mean over Lake Victoria

8.2.1.11.7 Sharing analysis #9 – Results of Precipitation Measurement Radar 2 8.2.1.11.7.1 Simulations for FSS (E-s) In this study, aggregate interference created by FSS earth stations into PMR2 is simulated. PMR2 has four channels of frequency agility with 8 MHz bandwidth of each channel, so the total bandwidth of PMR2 is 32 MHz. According to the deployment model used, 2 772 FSS Earth stations have been deployed worldwide in a frequency band of 32 MHz (see Fig. 8-63) using a uniform distribution. The number of different type of FSS Earth stations are given in Table 41.Each FSS Earth station is pointing to one GSO satellite chosen randomly between a total of 120 GSO satellites, one each 3 degrees, provided that a minimum elevation angle of 10° is respected. The PMR2 orbits are simulated during 4 days with a time step of 1 second. Rep. ITU-R S.2365-0 125

FIGURE 8-63 Location of the 2 772 FSS Earth stations

TABLE 8-40 Number of FSS Earth stations used in simulations for PMR2

Number of Number of Transmissi Number of Transmission Percentage of Total Transmissions in ons in Transmissions in Type Satellite Transmissions 32 MHz per 32 MHz for 500 MHz per satellite satellite 120 satellites VSAT 69.30% 246 16 1920 Wideband 4.90% 17 1.1 132 Point-to-Point 25.80% 92 6 720 All 100% 355 23.1 2772 The interference power I from one FSS Earth station received by the PMR2 receiver is,

퐼 = 퐸퐼푅푃 + 퐺푟 − 퐿푝 − 퐹퐷푅 where: 퐸퐼푅푃: FSS Earth station’s e.i.r.p. (dBW)

퐺푟: antenna gain of PMR2 at the direction of FSS Earth station (dB)

퐿푝: propagation loss of electromagnetic wave from FSS Earth station to PMR2 (dB) 퐹퐷푅: frequency dependent rejection (dB).

So the aggregated interference power 퐼푎푔 from all of the FSS Earth stations can be calculated as:

퐼푎푔 = 10푙푔 (∑ 퐼푖) where: th 퐼푖: interference power I from i FSS Earth station (W).

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FIGURE 8-64 Cdf of interference received on PMR2

As shown in Fig. 8-64, the 2772 FSS earth stations create an interference level of –131.3 dBW for 0.2% of the time in PMR2, therefore exceeding the protection criterion of –141.3 dBW with a margin of –10 dB.

8.2.1.11.7.2 Summary of sharing analysis #9 The performed dynamic simulations of the FSS (Earth-to-space) into EESS (active) precipitation radar shows the protection criterion for PMR2 is not satisfied with a –10 dB negative margin.

8.2.2 FSS (s-E) and ARNS The ARNS airborne Doppler navigation systems, installed in aircraft and helicopters, operate worldwide on a primary basis in the frequency band 13.25-13.4 GHz and are used for specialized applications such as continuous determination of ground speed and drift angle information of an aircraft with respect to the ground. The Radio Technical Commission for Aeronautics (RTCA) minimum operational performance standards (MOPS) for this equipment is found in “DO-158 – Airborne Doppler Radar Navigation Equipment”. In addition, radars used for collision avoidance on board unmanned aircraft (UA) are also planned to support the integrations of unmanned aircraft systems (UAS) in non-segregated airspace.

8.2.2.1 ARNS characteristics and protection criteria Recommendation ITU-R M.2008 ‒ Characteristics and protection criteria for radars operating in the aeronautical radionavigation service in the frequency band 13.25-13.40 GHz, provides: − The technical and operational characteristics of representative ARNS airborne radars operating in the 13.25-13.4 GHz frequency band, to be used in compatibility studies with systems in other services. − The criterion of interfering signal power to radar receiver noise power level, I/N of −10 dB, in Recommendation ITU-R M.2008, should be used as the required protection level for the aeronautical radionavigation radars, and that this represents the aggregate protection level if multiple interferers are present. Being a safety service, this protection criterion has to be met 100% of the time. Rep. ITU-R S.2365-0 127

Recommendation ITU-R M.1461 ‒ Procedures for determining the potential for interference between radars operating in the radiodetermination service and systems in other services, should be used in analysing compatibility between radars operating in the frequency band 13.25-13.4 GHz with systems in other services in this frequency band. The technical parameters of radionavigation radars operating in the frequency band 13.25-13.4 GHz are presented in Table 1 of Recommendation ITU-R M.2008. All systems are operated worldwide aboard aircraft. The radars are used for aircraft on-board navigation systems for accurate navigation in all weather conditions. Three out of eight radars in that table will be used as representative radars (covering altitudes from 0 to 15 km) to be used in the analysis of this sharing study. The relevant technical parameters of these three representative radars are listed in Table 8-41 below.

TABLE 8-41 Relevant technical radar parameters

Parameter Radar 1 Radar 4 Radar 5 Platform Aircraft (helicopter) Aircraft (airplane) Aircraft (helicopter) Platform max operational 3 600 15 000 0 – 4 500 altitude (m) Radar type Doppler navigation Doppler navigation Doppler radar velocity radar radar sensor Emission type CW CW FMCW Receiver IF –3 dB bandwidth 1.4 (estimated) 2.9 (estimated) 14 (kHz) Sensitivity (dBm) –135 for 0 dB S/N –138 for 3 dB S/N –130 for 3 dB S/N (V = 100 m/s) –160 for 3 dB S/N (V = hover) Receiver noise figure (dB) 22 (homodyne rx) 22 (homodyne rx) 22 (homodyne rx) Antenna placement Points towards earth Points towards earth Points towards earth Antenna gain (dBi) 27 29.5 26.5 First antenna side lobe (dBi) 5.5 14.2 at 4 degrees –10 Horizontal beamwidth (deg) 7 4.7 4.0 Vertical beamwidth (deg) 4.5 2.5 3.4 Polarization Linear Linear Linear # of beams 4 4 4 Antenna beam configuration Janus system. Janus system. Janus system. Approximate four Approximate four corners of a pyramid corners of a pyramid with each 18 degrees with each 20 degrees off-nadir off-nadir Antenna scan Scan is one beam at a N/A Scan is one beam at a time for each corner time for each corner of of the pyramid the pyramid

Aircraft radionavigation radars in the frequency band 13.25-13.4 GHz operate continuously during flight to determine speed and heading. This encompasses an altitude range from just off the ground to approximately 4 500 m for Helicopter and 15 000 m for Aircraft. Flight times can vary for many

128 Rep. ITU-R S.2365-0 hours, and typically the majority of the flight time is spent en route, but also some linger time at either the departure or destination points is expected. This type of system uses four antenna beams as shown in Fig. 8-65. The beams may transmit in pairs or sequentially, depending on the system design.

FIGURE 8-65 Example antenna beam pattern configuration from the aircraft

Aircraft

Angle of beam depression

Port back beam Port front beam

Starboard Starboard back front beam beam

M.2008-01 8.2.2.2 Consideration of previous studies Studies performed under WRC-12 agenda item 1.25 and reported in Report ITU-R M.2221 have shown that a pfd limit of –134 dBW/m²/MHz was required in order to protect UAS sense-and-avoid sensors from harmful interference in the band 13.25-13.4 GHz. Section 4 provides for the satellite e.i.r.p. a value of –20 dBW/Hz, corresponding to 40 dBW/MHz. This corresponds to a pfd spectral density of –122 dBW/m²/MHz, 12 dB above the limit. In order to meet the pfd limit of –134 dBW/m²/MHz, the satellite e.i.r.p. would therefore have to be reduced by 12 dB, which would not allow the FSS to offer its full service.

8.2.2.3 Sharing study #1: Sense and avoid radars in the ARNS This frequency band is used by the aeronautical radionavigation service (ARNS) on a primary basis. This use is limited to Doppler Navigation Aids (RR No. 5.497). One type of ARNS Doppler radar system will be used for sense and avoid (S&A) operations for unmanned aircraft (UA). The S&A radars will be used to provide information on nearby aircraft in order to maintain flight safety for UA’s operating in non-segregated airspace. The S&A radars have a safety of life mission. The proposed characteristics for two S&A ARNS Doppler radars are shown in Table 8-42. Rep. ITU-R S.2365-0 129

TABLE 8-42 Technical parameters of sense and avoid radar

Parameter Units Radar 1 Radar 2 Platform Aircraft Aircraft Platform height km Up to 20 Up to 15.5 Air to air traffic Air to air traffic collision collision avoidance avoidance system Radar type system (Doppler radar (Doppler radar navigation navigation aids) aids) Ground speed km/hr Up to 1 500 Up to 1 500 Frequency tuning range GHz 13.25-13.4 13.25-13.4 Emission type Phase coded pulses Phase coded pulses Pulse width s 1-2 2.5 Ns 0.1 to 0.2 for rise and 0.1 to 0.2 for rise and fall Pulse rise and fall times fall times times RF emission bandwidth at –40 dB MHz 30 28.5 Pulse repetition frequency pps 6 000-8 000 30 000 Average transmitter power W 25 to 35 (up to 50) 25 to 35 (up to 50) Receiver IF –3dB bandwidth MHz 0.7-1.1 14 Sensitivity dBm −122 for 10 dB SNR –98.6 for 13.1 dB SNR Receiver noise figure dB 3 2.7 Calculated Rx noise power dBW –140.6 –128.5 Antenna type Phased array Phased array Antenna placement Nose of aircraft Nose of aircraft Antenna gain dBi 28-32 28–32 First antenna side lobe dBi 15-19 19 Horizontal beamwidth degrees 5 5 Vertical beamwidth degrees 5 5 Linear vertical and Polarization Linear vertical horizontal degrees Vertical ±30 Vertical ±37 Antenna scan Horizontal ±110 Horizontal ±110 Protection criteria dB −10 −10

8.2.2.3.1 Interference scenarios There are two possible interference scenarios between the S&A ARNS Doppler radar and the proposed FSS downlinks: 1) The proposed FSS satellite downlink transmission causes interference into the S&A radar receiver. 2) The S&A radar transmission causes interference into the proposed FSS receive earth stations.

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8.2.2.3.2 Proposed FSS satellite downlink into S&A radar receiver The possibility exists that the S&A radar receiver will have main beam to main beam coupling with the proposed FSS satellite downlink. This is because the airborne UA can fly in a wide range of elevation angles and any azimuth, combined with the radar’s antenna scanning ability (±30° for Radar 1, ±37° for Radar 2 in the vertical plane, and ±110° in the horizontal/azimuth, relative to the UA). Thus it is possible for the S&A radar to point at the GSO arc, causing main beam to main beam coupling. It is not possible to guarantee the safe operation of the UA by restricting the S&A radar from pointing at the GSO arc. Based on the characteristics of the S&A radar, a pfd level that will protect the radar receiver from interference can be derived.

The received power threshold, Pr, that will cause interference in the S&A radar receiver is computed based on the formula:

Pr = I/N + (−144dBW + 10logBif(MHz) + NF) + losses Based on the parameters in Table 8-42 and assuming losses of 5 dB:

Pr = –145.6 dBW (in 1.1 MHz bandwidth) for Radar 1;

Pr = –134.8 dBW (in 14 MHz bandwidth) for Radar 2. The pfd in the receiver bandwidth is equal to Pr minus the effective antenna area. The max antenna gain for both Radars 1 and 2 is 32 dB. At 13.4 GHz, the effective antenna is –10.4 dB(m2). pfd = –135.2 dBW/m2/(1.1 MHz) for Radar 1; pfd = –124.4 dBW/m2/(14 MHz) for Radar 2. Normalizing to 1 MHz bandwidth: pfd = –135.6 dBW/m2/MHz for Radar 1; pfd = –135.9 dBW/m2/MHz for Radar 2. The difference between the two results can be traced back to the different noise figures: 3 and 2.7. Overall, the worst case must be used. A pfd level of –135.9 dBW/m2/MHz will protect the S&A radar receiver from interference from the proposed FSS satellite downlinks in the 13.25-13.4 GHz band.

8.2.2.3.3 S&A radar transmission into proposed FSS earth station receivers The possibility exists that the S&A radar transmitter will cause interference into the receiving FSS earth station. Since the S&A radar is a safety-of-life service, the receiving FSS earth stations will have to accept the interference. It should also be noted that the indicated interference to FSS earth stations will occur only in areas where these systems are authorized. However, deployment of these S&A radars is increasing, one administration has flown multiple platforms over 10,000 hours. Six interference scenarios will be considered: 1) Main lobe S&A radar into main lobe of receiving FSS earth station. This is the worst case, but also the least likely and shortest duration case because of the dynamic physical geometry between the UA, the S&A radar, and the FSS earth station. 2) Main lobe S&A radar into side lobe of receiving FSS earth station. 3) Main lobe S&A radar into back lobe of receiving FSS earth station. 4) Side lobe S&A radar into main lobe of receiving FSS earth station. 5) Side lobe S&A radar into side lobe of receiving FSS earth station. 6) Side lobe S&A radar into back lobe of receiving FSS earth station. Rep. ITU-R S.2365-0 131

The remaining three interference scenarios: back lobe of S&A radar into main / side / back lobe of receiving FSS earth station will be discussed. The interference power received by the receiving FSS earth station will be computed using the formula:

I (dBW) = PS&A (dBW) + GS&A (dB) + LP (dB) + GES (dB) where:

PS&A : 50 W = 17 dBW (the S&A radar transmitter power);

GS&A : 32 dB main lobe / 19 dB side lobe (the S&A transmit antenna gain);

LP : –134.9 dB (propagation loss at 13.325 GHz for a 10 km path);

GES (receiving FSS earth station gain: several antennas have been proposed; their diameters, main lobe gain, and side lobe gain are shown in Table 8-43):

TABLE 8-43 Receiving FSS earth station antenna diameter and gains (Source: Table 4-1) Antenna size metres 0.6 0.9 1.2 2.4 6 Typical gain dBi 36.7 40.2 42.7 48.7 56.6 Side lobe gain (based on S.1855 15 19.7 23.0 29 29 dBi or S.580) S.1855 S.1855 S.1855 (S.580) (S.580)

For the back lobe of the receiving FSS ES antenna: – Recommendation ITU-R S.1855 (see § 2.2) states the back lobe gain equals 0 dB for off-axis angles of 70 to 180 degrees. – Recommendation ITU-R S.580 refers to Recommendation ITU-R S.465, which states the back lobe gain equals –10 dB for off-axis angles of 48 to 180 degrees. The interference power received by the receiving FSS earth stations is shown in Table 8-44, as a function of S&A transmit antenna gain (i.e. main lobe or side lobe) and receiving FSS earth station diameter and gain (i.e. main lobe, side lobe, or back lobe).

TABLE 8-44 Received interference power, dBW

S&A antenna gain FSS ES main lobe side lobe antenna diameter antenna gain antenna lobe 32 dBi 19 dBi (metres) (dBi) main lobe 36.7 –49.2 –62.2 0.6 side lobe 15 –70.9 –83.9 back lobe 0 –85.9 –98.9

132 Rep. ITU-R S.2365-0

TABLE 8-44 (end)

S&A antenna gain FSS ES main lobe side lobe antenna diameter antenna gain antenna lobe 32 dBi 19 dBi (metres) (dBi) main lobe 40.2 –45.7 –58.7 0.9 side lobe 19.7 –66.2 –79.2 back lobe 0 –85.9 –98.9 main lobe 42.7 –43.2 –56.2 1.2 side lobe 23 –62.9 –75.9 back lobe 0 –85.9 –98.9 main lobe 48.7 –37.2 –50.2 2.4 side lobe 29 –56.9 –69.9 back lobe –10 –95.9 –108.9 main lobe 56.6 –29.3 –42.3 6 side lobe 29 –56.9 –69.9 back lobe –10 –95.9 –108.9

Based on the FSS characteristics, the received power threshold, Pr, that will cause interference in the receiving FSS earth station receiver is computed based on the formula: Pr (dBW) = I/N (dB) + (–144dBW + 10logBif(MHz) + NF (dB)) + losses (dB) where: I/N = –12.2 dB (assumed);

BIF (receiving FSS earth station bandwidth – several antennas have been proposed, their diameters and bandwidths are shown in Table 8-45):

TABLE 8-45 Receiving FSS earth station antenna diameter and bandwidth (Source: Table 4-3) Antenna size metres 0.6 0.9 1.2 2.4 6 Average MHz 25.9 1.8 0.5 0.7 0.5 Bandwidth NF = 3 dB (Noise Figure, assumed); Losses = 3 dB (assumed). The received power threshold for the receiving FSS earth stations is shown in Table 8-46, as a function of receiving FSS earth station diameter and bandwidth. Rep. ITU-R S.2365-0 133

TABLE 8-46 Receiver Threshold, dBW

FSS ES FSS ES P diameter bandwidth r metres MHz dBW 0.6 25.9 –136.1 0.9 1.8 –147.1 1.2 0.5 –153.2 2.4 0.7 –151.7 6 0.5 –153.2

The margin is calculated by subtracting the interference power from the received power threshold. A negative margin indicates the interference power exceeds the received power threshold, i.e. the receiver will experience interference. Margins, in dBW, are shown in Table 8-47.

TABLE 8-47 Margin, dBW

S&A antenna gain FSS ES

antenna main lobe side lobe diameter antenna lobe (metres) main lobe –86.9 –73.9 0.6 side lobe –65.2 –52.2 back lobe –50.2 –37.2 main lobe –101.9 –88.9 0.9 side lobe –81.4 –68.4 back lobe –61.7 –48.7 main lobe –110.0 –97.0 1.2 side lobe –90.3 –77.3 back lobe –67.3 –54.3 main lobe –114.5 –101.5 2.4 side lobe –94.8 –81.8 back lobe –55.8 –42.8 main lobe –123.9 –110.9 6 side lobe –96.3 –83.3 back lobe –57.3 –44.3

As shown in Table 8-47, the receiving FSS earth station will receive substantial interference from the S&A radar transmissions.

134 Rep. ITU-R S.2365-0

An analysis of Table 8-47 provides insight into the three remaining interference scenarios: back lobe of S&A radar into main / side / back lobe of receiving FSS earth station. The best-case existing margin (0.6 m FSS ES back lobe and S&A side lobe) is ‒37.2 dB. The gain of the side lobe of the S&A radar is 19 dB. The relationship between gain and margin is inversely linear. To achieve a margin of 0 dB, the gain would have to decrease by 37.2 dB, from 19 dB to –18.2 dB. Further reductions in antenna gain would be required in other cases where the existing margin is less than –37.2 dB (e.g. 0.6 m FSS ES back lobe and S&A main lobe margin is –50.2, requiring an additional decrease of 13 dB, to –31.2 dB). WP 5B does not believe such low antenna gains are achievable for the back lobe of the S&A radar. WP 5B has also considered the additional attenuation of the UA body and concluded that given the small size of existing UA platforms with this S&A radar, varying flight dynamics, and horizontal and vertical scanning of the S&A radar, the additional attenuation due to the UA body will not be sufficient to reliably overcome the negative margin. Therefore WP 5B believes the receiving FSS earth station will receive interference from the S&A radar transmission in all interference scenarios (all antenna coupling cases). It is worth further investigating the probabilities and durations of the interference scenarios detailed above to better determine the operational impact on the receiving FSS earth stations.

8.2.2.3.4 Summary A pfd level of –135.9 dBW/m2/MHz is necessary to protect the S&A radar receiver from interference from the proposed FSS satellite downlinks in the 13.25-13.4 GHz band. In addition, the receiving FSS earth stations will receive substantial interference from the S&A radar transmissions as shown in Table 8-47.

8.2.3 FSS (E-s) and ARNS 8.2.3.1 Study #1: FSS (E-s) and ARNS For the purpose of the study, 120 FSS satellites could be assumed at 3° spacing even if in some portions of the orbital arc less than or greater than 3 degrees spacing is employed. A minimum elevation angle of 10-20° for an earth station could be assumed or picked. This study assumes that there has been a large number of FSS ESs deployed worldwide and much more could potentially be deployed in the band allocated to FSS. Similar FSS ESs deployment density could be used in the proposed FSS 13.25-13.4 GHz frequency band. Since the FSS ES will interfere with the ARNS radars in the 13.25-13.4 GHz band, this sharing study only uses a much smaller deployment density of FSS ESs, assumingly deployed every 2° geodetic arc spacing (less than 5 000 FSS ESs worldwide) as an example for the sharing study in this band. Figure 8-66 shows the ground tracks of the 120 GSO satellites (along the equator). The figure also shows 1 satellite vehicle (SV) at –90° longitude with 0, 5, 10, 50, and 58 degrees visibility regions (red curves), and 3 SVs at –135°, –93°, and –45° longitudes with 10° visibility regions. As shown in the figure, FSS earth stations inside the 10° red circle region can communicate with the FSS GSO satellite (red square at –90° longitude) with elevation angles varied from 10°to 90°, and FSS earth stations in different portions of the region can also communicate with other FSS GSO satellites. Hence, the pointing angles of each FSS ES can vary in elevation angles as well as azimuth angles randomly. In this sharing study, only the FSS earth stations/VSATs with a minimum elevation angle of 10° pointed randomly to the FSS GSO satellites are used to determine the interference to the ARNS radars on-board aircraft. Rep. ITU-R S.2365-0 135

FIGURE 8-66 FSS GSO ground tracks and examples of FSS ES visibility regions

FSS GSO ground tracks & 1 SV @ -90o w/ (0/ 5/ 10/ 50/ 58)o visibility & 3 SVs @ (-135/ -93/ -45)o w/ 10o visibility

0o visibility

50o visibility 58o visibility

10o visibility

5o visibility

Figure 8-67 shows the maximum elevation angle as a function of geodetic latitude. From the Figure, the highest latitude that a FSS ES can see the FSS GSO satellite with a 10° elevation angle is around 71.45°.

FIGURE 8-67 FSS ES max elevation angle vs. geodetic latitude

FSS ES max elevation deg angle, 20

0 0 10 20 30 40 50 60 70 80 Geodetic latitude, deg

Since ARNS radars on aircraft can be illuminated by the FSS ES antenna main beams (up to ±3.6° at +15 dBi) and/or FSS ES antenna sidelobes (up to ±6° at +10 dBi, ±15° at 0 dBi, and at –5 dBi for angles > ±15°) as shown in Fig. 8-68, all FSS earth stations within the ARNS radio horizons of 0° visibility can interfere with the ARNS radars. Radio horizon distances to a 0° visibility for radar 1 (3.6 km altitude), radar 4 (15 km altitude), and radar 5 (4.5 km altitude) to a FSS ES (10 m height) assuming 4/3 earth model are 260.5 km, 518.2 km, and 289.7 km, as shown in Fig. 8-68 in terms of

136 Rep. ITU-R S.2365-0 arc spacing, along with the number of FSS earth stations inside the radio horizons, assuming the 2° arc spacing separation between FSS earth stations.

FIGURE 8-68 ARNS radar radio horizons and FSS ES in view

5 Radar 1 4 Radar 4 Radar 5

3 FSS ES

1 FSS ES

-1

Latitude Latitude arc spacing, deg -2

-3

-4

-5 -5 -4 -3 -2 -1 0 1 2 3 4 5 Longitude arc Spacing, deg

From Fig. 8-68, there are 5 FSS earth stations visible to radar 1 and radar 5, and 21 FSS earth stations visible to radar 4. ARNS doppler navigation radars onboard aircrafts can be illuminated by the main beam of one or more FSS ES and/or the sidelobes of the number of FSS ES visible to the aircrafts. Table 8-48 shows the interference case of a single FSS ES main beam illuminating an aircraft on the sidelobes of the receiver antenna gain, assuming at 0 dBi. The interference powers can exceed the maximum interference power thresholds by 53.7 dB.

TABLE 8-48 Single FSS ES Main beam to ARNS radars 1, 4, and 5

VSAT VSAT Wideband Wideband Wideband ES1 ES2 ES3 ES4 ES5 Transmit PSD, dBW/Hz –42 –49 –49 –54.2 –60

Tx antenna gain GT , dBi 37.2 50.5 51.7 57.2 60.8 Max e.i.r.p. density, dBW/Hz –4.8 1.5 2.7 3.0 0.8 Rx IF –3 dB bandwidth, kHz 1.4/2.9/14 (radars 1 / 4 / 5) Slant range, km 20.7/86.4/25.9

Path loss PL, dB 141.3/153.7/143.2

Rx Antenna Gain GR , dBi 0

Rep. ITU-R S.2365-0 137

TABLE 8-48 (end)

VSAT VSAT Wideband Wideband Wideband ES1 ES2 ES3 ES4 ES5 Received FSS power, dBW –114.6 –108.3 –107.1 –106.8 –109.0

(PSD+10logB+GT+GR-PL) –123.9 –117.6 –116.4 –116.1 –118.3 –106.5 –100.2 –99.0 –98.7 –100.9 Rx noise power, dBW –150.5/–147.4/–140.5 (–204 + 10 log B + NF) Max interference power, dBW –160.5/–157.4/–150.5 (using I/N = –10 dB) Exceedance, dB 45.9 52.2 53.4 53.7 51.5 33.5 39.80 41.0 41.3 39.1 44.0 50.3 51.5 51.8 49.6

Table 8-49 shows the interference case of the sidelobes of multiple FSS earth stations (using 0 dBi FSS sidelobe antenna gain) in view of the ARNS radars illuminating an aircraft on the sidelobes of the receiver antenna gain, assuming at 0 dBi. The interference powers can exceed the maximum aggregate interference power thresholds by 24.0 dB.

TABLE 8-49 Sidelobes of multiple FSS ESs to ARNS radars 1, 4, and 5

FSS ES1 FSS ES2 FSS ES3 FSS ES4 FSS ES5 Transmit PSD, dBW/Hz –42 –49 –49 –54.2 –60

Tx antenna gain GT , dBi 0 0 0 0 0 Rx IF –3 dB bandwidth, kHz 1.4/2.9/14 (radars 1/4/5)

Rx Antenna Gain GR , dBi 0 Received FSS power, dBW –136.6 –143.6 –143.6 –148.8 –154.6

Σ (PSD+10logB+GT+GR-PL) –145.7 –152.7 –152.7 –157.9 –163.7 –128.5 –135.5 –135.5 –140.7 –146.5 Rx noise power, dBW –150.5/–147.4/–140.5 (–204 + 10 log B + NF) Max interference power, dBW –160.5 / –157.4 / –150.5 (using I/N = –10 dB) Margin, dB Radar 1 24.0 17.0 17.0 11.8 6.0 Radar 4 11.7 4.7 4.7 –0.5 –6.3 Radar 5 22.0 15.0 15.0 9.8 4.0 These results in the above two tables show that the interference power from FSS ES to ARNS radars exceeds the protection criteria of the ARNS radars in the 13.25-13.4 GHz band by a large amount in the cases considered. These results should be taken into account should a primary FSS allocation in the Earth-to-space direction be considered in this frequency band.

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8.2.3.2 Study #2: Radionavigation systems characteristics Table 8-50 summarizes the key parameters of two DVS systems embarked on board helicopters or aircraft. It should be noted that these two systems do not represent a worst case, but to the contrary, systems for which the interference impact would be less.

TABLE 8-50

Parameter Radar 1 Radar 4 Platform Aircraft (helicopter) Aircraft (airplane) Platform maximum operational altitude (m) 3 600 15 000 Radar type Doppler navigation radar Doppler navigation radar The range of measured ground speed 333 1 047 (km/hr) Frequency (GHz) Fixed single channel Fixed single channel Emission type Continuous wave Continuous wave Peak transmitter power (W) 0.85 1.0 1.4 2.9 Receiver IF −3dB bandwidth (kHz) Estimated Estimated Sensitivity (dBm) −135 for 0 dB S/N −138 for 3 dB S/N Receiver noise figure (dB) 22 (Homodyne Receiver) 22 (Homodyne Receiver) Antenna type Parabolic reflector Phased array Antenna placement Points towards Earth Points towards Earth Antenna gain (dBi) 27 29.5 First antenna side lobe (dBi) 5.5 14.2 at 4 degrees Horizontal beamwidth (degrees) 7 4.7 Vertical beamwidth (degrees) 4.5 2.5 Polarization Linear Linear Number of beams 4 4 Employs Janus system. Approximate four corners of a Antenna beam configuration Employs Janus system pyramid with each 18 degrees off-nadir Scan is one beam at a time for Antenna scan Not available each corner of the pyramid Protection criteria (dB) −10 −10 Rep. ITU-R S.2365-0 139

FIGURE 8-69 Example antenna beam pattern configuration from the aircraft

Aircraft

Angle of beam depression

Port back beam Port front beam

Starboard Starboard back front beam beam

M.2008-01 8.2.3.2.1 FSS characteristics The minimum PSD of –67.6 dBW/Hz, corresponding to –7.6 dBW/MHz or 22.4 dBm/MHz associated with a –10 dBi antenna (far side lobes), leads to an e.i.r.p. of 12.4 dBm/MHz, which was considered in the study. The impact of the FSS antenna main beam or first side lobe was not assessed.

8.2.3.2.2 Scenario The minimal separation distance between an FSS ES and DNA aircraft is defined as the distance at which the DNA protection criteria is met. This protection criterion is related to the interference power IRF induced at the DNA frontend.

I(dDNA) = e.i.r.p. FSS – L(dDNA) + GDNA (8-2.1) where:

e.i.r.p. FSS: FSS e.i.r.p. density, L(d) : free-space path loss + atmospheric attenuation at a separation distance d,

GDNA : maximum DNA antenna gain. The path loss in dB along the slant range d between the FSS ES and the DNA antenna is calculated by equation L(d) = 32.4 + 20log f + 20log d + d/1000*Atm(f/1000) (8-2.2) as provided in Recommendations ITU-R P.525 and ITU-R P.836. For the FSS ES carrier frequency f a value of f = 13 300 MHz is chosen. For simplification, the antenna beam has been modeled using Recommendation ITU-R F.1245. The beam is therefore symetrical in all direction, whereas the actual beam has an elliptical form. In this first analysis the DNA aircraft is considered horizontal.

140 Rep. ITU-R S.2365-0

FIGURE 8-70 Scenario description

DNA aircraft

 h DNA FSS ES

d Trans

The interference is calculated in all 4 beams, depending on the altitude hDNA, the transversal distance dTrans, and the longitudinal distance.

8.2.3.2.3 Interference levels 8.2.3.2.3.1 Helicopter case The following graphs give the interference level that would be generated in the 4 antenna beams of the Doppler navigation aid Radar 1 on board an helicopter at an altitude of 400 m by an FSS earth station located just below the helicopter path (dTrans = 0m). Only the FSS antenna side lobe levels (at –10 dBi) are assumed.

FIGURE 8-71 Interference levels (FSS ES below helicopter path)

All four beams are equally impacted, but not at the same time (the 2 forward beams first, followed by the 2 backward beams later). The following graphs give the interference level that would be generated in the 4 antenna beams of the Doppler navigation aid Radar 1 on board an helicopter at an altitude of 400 m by a FSS ES located at 100 m from the helicopter path (dTrans = 100 m). Rep. ITU-R S.2365-0 141

FIGURE 8-72 Interference levels (FSS ES at 100 m from helicopter path)

All 4 beams are still impacted, but with much higher I/N on two of them, which are closer to the FSS ES.

8.2.3.2.3.2 Airplane case The following graphs give the interference level that would be generated in the 4 antenna beams of the Doppler navigation aid Radar 4 on board an airplane at an altitude of 400 m by a FSS ES located just below the airplane path (dTrans = 0 m).

FIGURE 8-73 Interference levels (FSS ES below airplane path)

All four beams are equally impacted, but not at the same time (the 2 forward beams first, followed by the 2 backward beams later). The following graphs give the interference level that would be generated in the 4 antenna beams of the Doppler navigation aid Radar 4 on board an airplane at an altitude of 400 m by a FSS ES located at 100 m from the airplane path (dTrans = 100 m).

142 Rep. ITU-R S.2365-0

FIGURE 8-74 Interference levels (FSS ES at 100 m from airplane path)

All 4 beams are still impacted, but the I/N values obtained are higher, due to the fact that the FSS ES is close to the DNA main beam.

8.2.3.2.4 Size of interference area 8.2.3.2.4.1 Helicopter case Figure 8-75 keeps only the cases of harmful interference (i.e. I/N > –10 dB), and gives in colour the I/N values obtained for an helicopter depending on its altitude and the distance from its path to the FSS Earth station.

FIGURE 8-75 Interference levels vs altitude and distance of the FSS station from the helicopter path

It can be seen that there is a quite large area with a potential of harmful interference to the DNA receiver. For example, a helicopter flying at 3 600 m may receive harmful interference from a FSS ES located between 300 m and 1 300 m away from the aircraft path. Rep. ITU-R S.2365-0 143

8.2.3.2.4.2 Airplane case Similarly, Fig. 8-76 keeps only the cases of harmful interference (i.e. I/N > –10 dB) for the airplane case.

FIGURE 8-76 Interference levels vs altitude and distance of the FSS station from the airplane path

It can be seen that there is a quite large area with a potential of harmful interference to the DNA receiver. For example, an aircraft flying at 10 000 m may receive harmful interference from a FSS ES located between 1 700 m and 3 200 m away from the aircraft path. Airplane flying below 5 000 m may create interference with I/N levels up to 43 dB, 53 dB above the protection criterion.

8.2.3.2.5 Duration of interference 8.2.3.2.5.1 Helicopter case Figure 8-77 gives in color the duration of harmful interference calculated in the four DNA antennas during the fly-by, depending on the altitude and the distance between the FSS ES and the helicopter path dTrans, assuming a speed of 200 km/h for the helicopter.

144 Rep. ITU-R S.2365-0

FIGURE 8-77 Harmful interference duration vs altitude and distance of the FSS station from the helicopter path

The duration of harmful interference in one beam is between less than 1 and more than 25 seconds. The interference duration increases with the altitude of the DNA helicopter as well as the distance between the FSS ES and the helicopter path.

8.2.3.2.5.2 Airplane case Figure 8-78 gives in color the duration of harmful interference calculated in the four DNA antennas during the fly-by, depending on the altitude and the distance between the FSS ES and the airplane path dTrans, assuming a speed of 500 km/h for the airplane.

FIGURE 8-78 Harmful interference duration vs altitude and distance of the FSS station from the aircraft path

The duration of harmful interference in one beam is between less than 1 and more than 19 seconds. The interference duration increases with the altitude of the DNA airplane as well as the distance between the FSS ES and the DNA airplane path. The lower duration of interference compare to the helicopter case is due to the difference in aircraft speed. Rep. ITU-R S.2365-0 145

8.2.3.3 Summary of study The studies show that, even when considering only the far side lobe levels of FSS Earth stations and two victim systems with non-worst-case characteristics, harmful interference would be created in Doppler Navigation Aids by one single FSS Earth station, with I/N levels up to 53 dB above the protection criterion. A helicopter may fly about everywhere, thus being potentially affected by all FSS Earth stations that would be deployed worldwide. Nearly all modern helicopters are equipped with this kind of navigation system worldwide. Further work may be needed to evaluate the interference due to the FSS ES main beam, as well as the aggregate impact of several FSS ES in visibility of the aircraft, but this first study already shows that sharing between FSS (Earth-to-space) and Doppler Navigation radars in the band 13.25-13.4 GHz is not feasible. The impact of FSS uplinks into UAS sense-and-avoid sensors still needs to be studied.

8.2.4 FSS (s-E) and SRS (active) Since SRS (active) applications are active sensors used around other planets no compatibility issue with FSS is expected.

8.2.5 FSS (E-s) and SRS (active) In respect of the space research service (SRS), earlier studies identified no existing or planned use of this band. Since SRS (active) applications are active sensors used around other planets no compatibility issue with FSS is expected.

8.2.6 FSS (s-E) and FS No sharing studies were submitted to the ITU-R for FSS (s-E) satellite systems and fixed systems in the band 13.25-13.4 GHz.

8.2.7 FSS (E-s) and FS No sharing studies were submitted to the ITU-R for FSS (E-s) satellite systems and fixed systems in the band 13.25-13.4 GHz.

8.3 Summary of studies for the band 13.25-13.4 GHz 8.3.1 EESS (active) and FSS (space-to-Earth) With regard to sharing between EESS (active) and FSS (space-to-Earth), seven studies have been performed. The detail study results could be found in §§ 8.2.1.10.1, 8.2.1.10.2 and 8.2.1.10.3.

8.3.2 EESS (active) and FSS (Earth-to-space) With regard to sharing between EESS (active) and FSS (Earth-to-space), seven studies have been performed to date on a global basis using the systematic data availability protection criteria from Recommendation ITU-R RS.1166-4. Two of the studies performed examined compatibility for specific measurement areas of interest. Satisfying both criteria is required to ensure protection of EESS operations. Three of the global studies indicate that the EESS (active) protection criteria is always met for all kinds of sensors considered, assuming an FSS frequency reuse factor of 1.2. However, EESS (active) altimeters have lower margins of compatibility from 3 to 6 dB below protection criteria, than scatterometers and precipitation radars.

146 Rep. ITU-R S.2365-0

Another global study indicates that FSS (E-s) with EESS (active) are compatible subject to some FSS (E-s) parameters restriction. According to the results of these studies, compatibility is achieved for all transmission types of FSS (E-s) earth stations with antenna diameters from 0.6 m to 9 m with a maximum peak envelope power spectral density less than or equal to –50.8 dBW/Hz. Another global study provides a parametric analysis varying the FSS GSO frequency reuse factor from an FRF of 1.2 to 4. The parametric studies also examined varying the FSS deployment transmission types by percentage of transmissions. The results of the parametric study indicated that starting at the range of an FRF of 2 (1-sigma e.i.r.p. level), compatibility will fail the protection criteria on a global basis for all variances of FSS deployment transmission types assumed in the study. In addition, an study examining the simplifying assumption of using a single continuously transmitting earth station in place of a TDMA network was done, showing that this simplifying assumption underestimates the amount of interference seen by the JASON-3 altimeter sensor by 3.4 dB considering a FSS deployment model comprised of 100% VSAT employing TDMA and 0% of Wideband and Point-to-Point employing TDMA. If the FSS satellite frequency reuse factor is increased to 3 or 4, compatibility is no longer ensured, noting that a frequency reuse factor of 1.2 ensures compatibility. Further assessment is required to determine a potential realistic future frequency reuse factor. When considering compatibility between EESS (active) and FSS (Earth-to-space) on the basis of specific measurement area of interest, two of the studies show that, when examining specific measurement areas of interest (sea/land/wet areas) for EESS (active) altimetry, the protection criteria were exceeded over large portions of the Earth. A single earth station uplink of median transmit power can corrupt the sensor measurements of a specific measurement area of interest. In one of the studies it was shown that the sharing criteria is not met for regions of the Earth extending from the equator to ±10 degrees latitude (VSAT) to ±45 degrees latitude (wideband). The analyses examined the impact on a single EESS (active) altimeter in a repeating orbit. No study examined the impact that FSS (Earth-to-space) would have on the full number of altimeters currently operating in separate unique repeating orbits or other altimeters that will operate in the future. A specific mitigation technique to address sharing has not yet been identified. Coordination was examined as a possible mitigation technique and found to require knowledge of future EESS (active) systems which cannot be provided, pointing of FSS ES mainbeams to avoid intersection with EESS (active) spacecraft orbital paths, potential repointing of existing FSS ESs impacted by the introduction of a new EESS (active) spacecraft, and addressing aggregate interference from multiple FSS ESs that could exceed the protection criteria of the EESS (active) sensors in operation. As a result of this situation, coordination is an unsatisfactory mitigation technique as described in § 8.2.1.11.6. One study performed dynamic simulations of the FSS (Earth-to-space) with EESS active precipitation radar, and showed the protection criteria for Precipitation Measurement Radar 2 (PMR2) were not satisfied, exceeding the interference threshold by 10 dB.

8.3.3 FSS (s-E) and ARNS A pfd level of –135.9 dBW/m2/MHz is necessary to protect the S&A radar receiver from interference from the proposed FSS satellite downlinks in the 13.25-13.4 GHz band. In addition the interference at the receiving FSS earth stations will exceed the protection criteria by 123.9 dB from the S&A radar transmissions as shown in Table 8-47. FSS receiving earth station operating near the band edges need to be mindful of this level of interference.

8.3.4 FSS (E-s) and ARNS Studies show that, even when considering only the far side lobe levels of FSS Earth stations and two victim systems with non-worst-case characteristics, harmful interference would be created in airborne Doppler Navigation Aids by one single FSS Earth station, with I/N levels up to 53 dB above the protection criterion. A helicopter may fly about everywhere, thus being potentially affected by all Rep. ITU-R S.2365-0 147

FSS Earth stations that would be deployed worldwide. Nearly all modern helicopters are equipped with this kind of navigation system worldwide. Studies show that sharing between FSS (Earth-to-space) and ARNS airborne Doppler Navigation radars in the band 13.25-13.4 GHz is not feasible.

9 Frequency band 13.4-13.75 GHz The allocations of this band in RR Article 5 are shown below.

TABLE 9-1 Excerpts from Article 5 of the Radio Regulations on allocation to services in 13.4-13.75 GHz

Allocation to services

Region 1 Region 2 Region 3 13.4-13.75 EARTH EXPLORATION-SATELLITE (active) RADIOLOCATION SPACE RESEARCH 5.501A Standard frequency and time signal-satellite (Earth-to-space) 5.499 5.500 5.501 5.5.01B

5.499 Additional allocation: in Bangladesh and India, the band 13.25-14 GHz is also allocated to the fixed service on a primary basis. In Pakistan, the band 13.25-13.75 GHz is allocated to the fixed service on a primary basis. (WRC-12) 5.500 Additional allocation: in Algeria, Angola, Saudi Arabia, Bahrain, Brunei Darussalam, Cameroon, Egypt, the United Arab Emirates, Gabon, Indonesia, Iran (Islamic Republic of), Iraq, Israel, Jordan, Kuwait, Lebanon, Madagascar, Malaysia, Mali, Morocco, Mauritania, Niger, Nigeria, Oman, Qatar, the Syrian Arab Republic, Singapore, Sudan, South Sudan, Chad and Tunisia, the band 13.4-14 GHz is also allocated to the fixed and mobile services on a primary basis. In Pakistan, the band 13.4-13.75 GHz is also allocated to the fixed and mobile services on a primary basis. (WRC-12) 5.501 Additional allocation: in Azerbaijan, Hungary, Japan, Kyrgyzstan, Romania and Turkmenistan, the band 13.4-14 GHz is also allocated to the radionavigation service on a primary basis. (WRC-12) 5.501A The allocation of the band 13.4-13.75 GHz to the space research service on a primary basis is limited to active spaceborne sensors. Other uses of the band by the space research service are on a secondary basis. (WRC-97) 5.501B In the band 13.4-13.75 GHz, the Earth exploration-satellite (active) and space research (active) services shall not cause harmful interference to, or constrain the use and development of, the radiolocation service. (WRC-97)

9.1 Review of Recommendations/Reports A list of relevant Recommendations and Reports that may be useful for sharing studies is in Table 9-2.

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TABLE 9-2 Summary of relevant Recommendations/Reports that may be useful for sharing studies in the band 13.4-13.75 GHz

Service Relevant Recommendations/Reports Fixed Recommendation ITU-R F.699 Recommendation ITU-R F.758 Recommendation ITU-R F.1107 Recommendation ITU-R F.1245 Recommendation ITU-R F.1333 Recommendation ITU-R F.1336 Recommendation ITU-R F.1777 Mobile None Earth exploration-satellite (active) Recommendation ITU-R RS.1166 Report ITU-R RS.2068 Radionavigation None Service Relevant Recommendations/Reports Radiolocation Recommendation ITU-R M.1644 Recommendation ITU-R M.1461 Recommendation ITU-R M.1851 Space research Recommendation ITU-R SA.609 Recommendation ITU-R SA.510 Recommendation ITU-R SA.1019 Recommendation ITU-R SA.1155 Recommendation ITU-R SA.1018 Recommendation ITU-R SA.1414

9.2 Sharing studies for the band 13.4-13.75 GHz 9.2.1 FSS (s-E) and EESS (active) See § 8.

9.2.1.1 FSS characteristics The e.i.r.p. spectral density of the FSS satellite on downlink is –20 dBW/Hz (40 dBW/MHz).

9.2.2 FSS (E-s) and EESS (active) See § 8.

9.2.3 FSS (s-E) and RLS, RNS The band 13.4-13.75 GHz is used by the same radars as in the band 13.75-14 GHz. Indeed Recommendation ITU-R M.1644, which lists the radar characteristics for the band 13.75-14 GHz in its considering g), that “some radiolocation and radionavigation radars operate in both the 13.75-14 GHz band and the 13.4-13.75 GHz band”. Considering the protection criteria for the radars operating in the radiodetermination services I/N = –6 dB and the radar characteristics the permissible interference level at the radar receiver is ‒135 dB(W/10 MHz). Rep. ITU-R S.2365-0 149

The maximum power flux density emitted by one FSS satellite on GSO in the radar receiving antenna location with the effective antenna area of G·λ2/4π at the frequency 13.5 GHz is defined by the following equation: pfd = 99 Gr dBW/(m2 1MHz) max where: Gr – maximum radar receiving antenna gain. The radar has two operation modes: “search” and “track” and 2 separate antennas for each of the indicated operation modes accordingly. In “search” mode the radar antenna pattern has two configurations. Configuration 1 elevation coverage is accomplished using one 10º antenna centred at 4.5º (1F) and one 20º antenna (4F) centred at 60º, both facing forward, and two 20º antennas centred at 20º (2B) and 40º (3B), both facing backward. Figure 9-1 presents the composite elevation coverage pattern with all antennas superimposed. Table 9-3 lists parameters of the search antennas and pfd limits.

FIGUREFIGURE 9 1-1 Configuration 1 search main beam patterns

1F 2B

1644-01 TABLE 9-3 pfd limits to protect radar configuration 1 search mode

Azimuth Elevation Elevation Antenna Gain pfd beamwidth beamwidth beam centre position (dBi) dBW(m21MHz) (degrees) (degrees) (degrees) 1F 2.2 10 4.5 31.5 –130.5 2B 2.2 20 20 28.5 –127.5 3B 2.2 20 40 28.5 –127.5 4F 2.2 20 60 28.5 –127.5

150 Rep. ITU-R S.2365-0 presents the composite elevation coverage pattern with all antennas superimposed. Table 9-4 lists parameters of the search antennas and pfd limits.

FIGUREFIGURE 9 2-2 Configuration 2 search main beam patterns

4F 3B

1F 2B

1644-02

TABLE 9-4 pfd limits to protect radar configuration 2 search mode

Azimuth Elevation Elevation Antenna Gain pfd beamwidth beamwidth beam centre position (dBi) dBW(m21MHz) (degrees) (degrees) (degrees) 1F 2.2 2.5 0 37.5 –136.5 2B 2.2 2.5 0 37.5 –136.5 3B 2.2 10 6.25 31.5 –130.5 4F 2.2 10 16.25 31.5 –130.5

The obtained pfd limits are valid for the arrival angles of interfering signal δ = Elevation beam centre+Elevation beamwidth/2. Then pfd mask for protection of radar in the “search” mode with configuration 2 is the following:  136.5 dBW /(m2 1MHz) for 0   1.25  2   pfdmax = 130.5 dBW /(m 1MHz) for 1.25    21.25  2    115 dBW /(m 1MHz) for 21.25    90 “Track” mode The track antenna is a monopulse four-horn fed parabolic dish segment with elevation beamwidth of 1.2º and azimuth beamwidth of 2.4º; gain is 38.5 dBi and side lobe levels are more than 20 dB below the main lobe. When designated to acquire a target, the antenna executes a limited size raster pattern and goes into track when the target is detected. The parameters of “track” mode in accordance with Recommendation ITU-R M.1644 are presented in Table 9-5.

Rep. ITU-R S.2365-0 151

TABLE 9-5 Characteristics of radar in track mode

Parameter Values for “track” mode Antenna type Parabolic reflector Antenna mainbeam gain(s) (dBi): 38.5 Antenna elevation beamwidth (degrees) 1.2 Antenna azimuthal beamwidth (degrees) 2.4 Antenna horizontal scan rate (degrees/s) Follows target Antenna horizontal scan type (continuous, random, Follows target 360º, sector, etc.) (degrees) Antenna vertical scan rate (degrees/s) Not applicable Antenna vertical scan type (continuous, random, 360º, Not applicable sector, etc.) (degrees) Antenna side-lobe (SL) levels (1st SLs and remote –18.5 dB SLs)

As the table shows the radar antenna in the “track” mode follows the target in the whole azimuth range and the horizontal scan is not applied in this mode:

TABLE 9-6 pfd limits to protect radar in track mode

Azimuth Elevation Elevation Antenna Gain pfd beamwidth beamwidth beam centre position (dBi) dBW(m21MHz) (degrees) (degrees) (degrees) 1 2.4 1.2 0 38.5 –137.5 pfd mask for protection of the radar in the “track” mode:

137.5 dBW /(m2 1MHz) for 0    0.6 pfd = max  2   119 dBW /(m 1MHz) for 0.6    90 Therefore based on the estimation results 3 pfd masks were obtained: 2 masks for the “search” mode and one for “track” mode. These masks are summarized in the output mask based on the “most stringent limit” criteria. In this case the output pfd mask for the protection of radar is the following:

 137.5 dBW /(m2 1MHz) for 0    0.6  2    136.5 dBW /(m 1MHz) for 0.6   1.25  2   pfdmax = 130.5 dBW /(m 1MHz) for 1.25    21.25  2    127.5 dBW /(m 1MHz) for 21.25    70 2    119 dBW /(m 1MHz) for 70    90 The obtained limits for FSS satellite pfd levels for each mode of the radar and also the summarized pfd mask are shown in the Figure below.

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FIGURE 9-3 FSS satellite pfd mask for protection of radiolocation and radionavigation radars

-105 0 10 20 30 40 50 60 70 80 90

-110

-115

-120 Search 1 Search 2 Track -125

Summary PFD Mask pfd level, pfd dBW(m2MHz)level,

-130

-135

-140 arrival angle, grad.

Summary Compatibility conditions between FSS (space-to-Earth) and RLS, RNS stations are possible based on pfd limits into FSS space stations.

9.2.4 FSS (E-s) and RLS The band 13.4-13.75 GHz is used by the same radars as in the band 13.75-14 GHz. Indeed Recommendation ITU-R M.1644, which lists the radar characteristics for the band 13.75-14 GHz in its considering g), that “some radiolocation and radionavigation radars operate in both the 13.75-14 GHz band and the 13.4-13.75 GHz band”. This Recommendation also provides the protection threshold criteria that should be applied to radiolocation operations in this band. In addition, at least one administration operates aeronautical scatterometer and precipitation radar under the radiolocation allocation in the 13.4-13.75 GHz band. Static calculations have been performed using the parameters of one of the precipitation radar systems (HIWRAP) showing that a main beam to main beam coupling will not induce a burnout of the RF frontend. At a minimum, the provisions existing in the band 13.75-14 GHz shall also apply in the band 13.4 13.75 GHz, and, in particular, RR No. 5.502. 5.502 In the band 13.75-14 GHz, an earth station of a geostationary fixed-satellite service network shall have a minimum antenna diameter of 1.2 m and an earth station of a non-geostationary fixed- satellite service system shall have a minimum antenna diameter of 4.5 m. In addition, the e.i.r.p., averaged over one second, radiated by a station in the radiolocation or radionavigation services shall not exceed 59 dBW for elevation angles above 2° and 65 dBW at lower angles. Rep. ITU-R S.2365-0 153

Before an administration brings into use an earth station in a geostationary-satellite network in the fixed-satellite service in this band with an antenna diameter smaller than 4.5 m, it shall ensure that the power flux-density produced by this earth station does not exceed: – –115 dB(W/(m2 · 10 MHz)) for more than 1% of the time produced at 36 m above sea level at the low water mark, as officially recognized by the coastal State; – –115 dB(W/(m2 · 10 MHz)) for more than 1% of the time produced 3 m above ground at the border of the territory of an administration deploying or planning to deploy land mobile radars in this band, unless prior agreement has been obtained. For earth stations within the fixed-satellite service having an antenna diameter greater than or equal to 4.5 m, the e.i.r.p. of any emission should be at least 68 dBW and should not exceed 85 dBW. (WRC-03) In addition, some administrations might have migrated their radiolocation radar systems operating in the 13.75-14 GHz in the lower part of the band, in order to avoid harmful interference from a higher number of FSS Earth stations following the revision of sharing conditions in this band under WRC-03 AI 1.24. An allocation to FSS (Earth-to-space) in this band would therefore have a significant impact on radar operation in the radiolocation service.

9.2.4.1 Aeronautical Radionavigation characteristics HIWRAP is a dual-frequency (Ka- and Ku-band), dualbeam (300 and 400 incidence angles), conical scanning, Doppler radar system designed for operation on the NASA high-altitude (65,000 ft) Global Hawk Unmanned Aerial System (UAS). By combining measurements at 13.25-13.75 and Ka-band, HIWRAP is able to image winds through measuring volume scattering from clouds and precipitation. In addition, HIWRAP is also capable of measuring surface winds in an approach similar to SeaWinds on QuikScat. The relevant operational characteristics required for a compatibility analysis with FSS (E-s) of HIWRAP are provided in Table 9-7.

TABLE 9-7 Aeronautical HIWRAP Characteristics Altitude (km) 10.0 35.4 (inner) Antenna Pk Rcv gain (dBi) 35.4 (outer) V (inner), Polarization H (outer) Azimuth scan rate (rpm) 30 30 (inner) Antenna beam look angle (deg) 40 (outer) Antenna beam azimuth angle (deg) 0-360 Transmit Pk pwr (W) 25 Antenna beamwidth (deg) 2.9 13.910 (inner) RF center frequency (MHz) 13.470 (outer) RF bandwidth (MHz) 100 System noise temperature (deg K) 290 K Interference Protection Criteria, (I/N dB) −6 Sensor Damage Criteria (dBW) –10

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The HIWRAP sensor antenna gain pattern is provided in Fig. 9-4. The sensor was modeled with two scanning swaths rotating at 30 rpm at conical angles of 30 degrees (inner beam) and 40 degrees (outer beam).

FIGURE 9-4 HIWRAP antenna gain (dB) pattern used in interference simulation

9.2.4.2 Static analysis A static analysis was conducted using four scenarios. The first static scenario considered the interaction between the HIWRAP and the FSS transmission types defined in Report ITU-R S.2364 that would result from nominal operation of the HIWRAP on-board a UAV at 10 km altitude and level flight. The second static scenario considered the interaction that could occur if the UAV was not on a level flight course resulting from aeronautical banks, rolls, or disturbance that could result in a main-beam to main-beam coupling of the earth station and HIWRAP antennae. Scenarios three and four examined the full range of antenna interactions between the three FSS transmission types operating at average power as provided in Table 3 of Report ITU-R S.2364 and the HIWRAP aeronautical Precipitation Radar operating under the RLS. Tables 9-9 and 9-10 summarize the results of the first two scenarios, earth station transmission type, as well as the FSS earth station median, +1 sigma, and +2 sigma e.i.r.p. values provided in Table 9.8. This is evaluated against the Recommendation ITU-R M.1644 protection criteria of –6 dB I/N corresponding to –130 dBW/100 Mhz. Maximum allowable sensor input power is –10 dBW, and the RF front end saturates at –50 dBW.

TABLE 9-8 FSS characteristics used for Area of Interest studies

BW Antenna Size Average Power +1 STD +2 STD (MHz) (m) (dBw/Hz) (dBW/Hz) (dBW/Hz) VSAT 0.6 1.2 –9.23 –6 –5.62 Wideband 30.8 2.8 –3.4 0.5 –2 Point-Point 2.94 3.8 –5.62 1 3

Rep. ITU-R S.2365-0 155

TABLE 9-9 Interference peak powers anticipated (single source) for the three transmission types (level flight)

VSAT Wideband Point to Point Median (dBW) –98 –82 –97 E.I.R.P. +1 sigma (dBW) –96 –80 –95 E.I.R.P. + 2 sigma (dBW) –94 –79 –93

TABLE 9-10 Interference peak powers anticipated (single source) for the three transmission types (main-beam-to-main-beam)

VSAT Wideband Point to Point Median (dBW) –48 –32 –47 E.I.R.P. +1 sigma (dBW) –46 –30 –40 E.I.R.P. + 2 sigma (dBW) –44 –29 –43

The results of the static analysis indicate that under all cases considered the interference from the FSS (E-s) will not exceed the RF front end saturation or maximum allowable sensor input power of the HIWRAP. The results for the static analysis show that the threshold protection criteria are exceeded by a minimum of 33 dB for the nominal flight case and a minimum of 82 dB for the case examining main-beam to main-beam coupling. Scenario 3 examines the situation where the HIWRAP sensor antenna boresight is directed towards the FSS earth station and the FSS transmit gain is at minimum. The FSS antenna off-boresight gain used for the analysis is provided from Recommendation ITU-R S.580-6. The line of sight path distance for this case is 26.1 km. This case shows the interference levels when disregarding the directivity of FSS transmitters and when the HIWRAP antenna would be pointed directly towards an FSS earth station; an event that would be expected to occur during its routine operations. Scenario four assumes the minimum elevation angle (10 degrees) as provided by Report ITU-R S.2364 for the FSS earth station where its transmit boresight intersects the HIWRAP sensor antenna while the HIWRAP receive gain is at minimum. The on-sight antenna gain is provided by Recommendation ITU-R BO.1213-1. The line of sight path distance is 115.18 km. This case shows the maximum interference seen by HIWRAP when FSS earth stations are restricted to the lowest possible transmission elevation angle of 10 degrees. Figure 9-5 shows the alignment of FSS earth station and HIWRAP antennas for Scenarios 3 and 4.

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FIGURE 9-5 FSS earth station and HIWRAP antenna alignments for the two cases studied

Scenarios 3 and 4 show that regardless of FSS transmit gain or elevation angle, exceeding the RLS protection criteria for the HIWRAP sensor is unavoidable. This conclusion is valid for Point-to-Point, Wideband, and VSAT FSS transmission types. Table 9-11 summarizes the –6 dB I/N criteria established in Recommendation ITU-R M.1644 for the three FSS transmission types for the two cases described above. When considering scenario three and four for each transmission type, the maximum value of these two scenario is the degree of exceedance that must be avoided to ensure compatible operations between FSS (E-s) and HIWRAP. Therefore, regardless of the FSS earth station antenna pointing, in order to not exceed the protection criteria the FSS earth station transmit power would have to be reduced, at a minimum, 22.37 dB, 27.07 dB and 39.70 dB, respectively, for the VSAT, Wideband and Point-to-Point transmission types. Such a reduction in FSS transmit power would render FSS operation infeasible.

TABLE 9-11 FSS (E-s) exceedance for Aeronautical RLS: two cases

Transmission FSS Case 1 Exceed Case 2 Exceed Type diameter (m) –6 dB I/N (dB) –6 dB I/N (dB) VSAT 1.2 22.37 16.77 Point-to-Point 2.8 22.66 27.07 Wide-band 3.8 37.95 39.70

As a result of these studies it can be concluded that neither a reduction in FSS earth station transmit power nor a restriction in FSS earth station elevation angle would be a viable mitigation technique to satisfy the HIWRAP protection criteria.

9.2.4.3 Dynamic simulation of FSS interference into UAV-borne HIWRAP scatterometer/precipitation victim sensor system Two separate dynamic simulations were performed examining the interference that might be encountered by HIWRAP scatterometer while deployed on missions over the Gulf of Mexico.

9.2.4.3.1 Study #1 In Study 1, a dynamic simulation was performed modeling an interference scenario involving a victim UAV-borne HIWRAP (High-Altitude Imaging Wind and Rain Airborne Profiler) sensor system and FSS regional deployment using a frequency reuse factor (FRF) of 1.2. Utilizing the deployment model described in § 5, a global deployment of FSS earth stations was generated where the VSAT and Wideband transmission types were uniformly distributed and the Rep. ITU-R S.2365-0 157

Point-to-Point transmission type was deployed according to population centers as described in Report ITU-R S.2364. The FSS earth stations that were considered to not be possible to interact with the HIWRAP sensor were not included in the simulation. The reason for this was selection of earth stations was to reduce the computational overhead in producing the simulation results. Each FSS earth station was pointing to one GSO satellite chosen randomly between a total of 120 GSO satellites (3 degree spacing) within view of the South West region of the United States. A minimum FSS antenna elevation angle of 10° was respected. The land based deployment was centered at 27N/86W with a radius 1000 km. The FSS (E-s) deployment numbers of the three earth station transmission types for the FRFs studied is provided in Table 9-12. The median power reported for the FSS transmission types per Table 9-8 was used in all simulations.

TABLE 9-12 FSS Earth Station Deployment numbers for the dynamic simulation

Frequency reuse Total earth VSAT Wideband Pt-to-Pt factor stations FRF 1.2 32 0 12 44

Four hundred flight paths of the HIWRAP instrument was selected over the FSS deployment area in the South East portion of the United States. This is a region where the instrument could be deployed to gather data on weather events including hurricanes. The flight path of the aircraft was chosen to provide for variability in aircraft heading. CDF analysis results for the cumulative 400 flight paths are provided in Fig. 9-6. Table 9-13 provides the results according to Recommendation ITU-R M.1644 prescribed protection criteria of –6 dB I/N.

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FIGURE 9-6 Interference Statistics of FSS Uplink Interference into HIWRAP

TABLE 9-13 Interference Statistics of FSS Uplink Interference into UAV Active Sensor

dB Exceedance at –6 dB I/N Frequency Reuse Factor Rec. ITU-R M.1644

FRF 1.2 4.4

The results of the parametric dynamic analysis of study 1 show that the Recommendation ITU-R M.1644 prescribed protection criteria of –6 dB I/N (equivalent to –130 dBW/100 MHz for HIWRAP) is exceeded for all FRFs between 1.2 and 5 for the area of measurement.

9.2.4.3.2 Study #2 In Study 2, a dynamic simulation was performed modelling an interference scenario involving a victim UAV-borne HIWRAP (High-Altitude Imaging Wind and Rain Airborne Profiler) sensor system and an interfering FSS regional deployment. Utilizing the deployment model described in § 5, a global deployment of FSS earth stations was generated where the VSAT, Wideband and the Point-to-Point transmission type was deployed worldwide (50% according to population density & 50% according to uniform distribution). he number of total stations in the simulation was obtained by considering, as starting point, the statistics of the model (i.e. % of total bandwidth for each type of antenna and occupied bandwidth for each type of antenna) in order to reach the total amount of spectrum used by satellites in this simulation (i.e. 100 MHz = 250 MHz  1.5  120 satellites)(single polarization considered). Table 9-14 was used a starting point based on the FSS distribution model in Report ITU-R S.2364. The simulation model that was developed took the average bandwidths for each transmission type Rep. ITU-R S.2365-0 159 from the FSS deployment model and then generated a Gaussian distribution. Each FSS earth station was given a random bandwidth based on the probability curve. The resulting average bandwidths for each transmission type of the simulation distribution was higher than average bandwidths of the FSS distribution in Report ITU-R S.2364. This deviation resulted in a global simulation model number of 3,595 FSS earth stations instead of the global distribution of 5,325 FSS earth stations that would result from using the average parameter values in Report ITU-R S.2364. The larger bandwidth did result in a higher e.i.r.p. for each earth station as well.

TABLE 9-14 FSS antenna characteristics used in simulation

A flight path of the HIWRAP instrument was selected over the South East portion of the United States. This is a region where the instrument could be deployed to gather data on weather events including hurricanes. The flight path of the aircraft was chosen to provide for variability in aircraft heading. It should be noted that HIWRAP does not have the same flight plan for every flight it undertakes and the flight path will vary based on weather conditions for the purpose of obtaining measurements required by the science team. This situation requires that many possible flight paths should be evaluated for its susceptibility to interference. It should also be noted that the interference seen by HIWRAP is highly dependent on the flight pattern. Figure 9-7 shows the deployed FSS earth stations that were considered possible to interact with the HIWRAP sensor during the simulation. Each FSS earth station was pointing to one GSO satellite chosen randomly between a total of 120 GSO satellites (3 degree spacing) within view of the South West region of the United States. A minimum FSS antenna elevation angle of 10° was respected.

160 Rep. ITU-R S.2365-0

FIGURE 9-7 Location of the FSS earth stations

Interference results for the 40 degrees conical scanning mode are provided in Fig. 9-8.

FIGURE 9-8 Interference results for the 40 deg conical scanning mode

9.2.4.4 Summary of Results Two studies with a static and dynamic analysis were performed using the HIWRAP aeronautical precipitation radar/scatterometer which operates under the radiolocation service. The Study #1-#4 results of the static analysis considered the FSS transmission type average,1-sigma, and 2-sigma deviations. The results of the static analysis indicate that under all cases considered the interference from the FSS (E-s) will not exceed the RF front end saturation or maximum allowable sensor input power of the HIWRAP. Static analysis was performed to examine the full range of antenna interactions between the three FSS transmission types operating at average power as described in Report ITU-R S.2364 and the HIWRAP aeronautical Precipitation Radar operating under the RLS. As a result of these studies it can be concluded that neither a reduction in FSS earth station transmit power nor a restriction in FSS earth station elevation angle is a feasible mitigation technique to satisfy the HIWRAP protection criteria. Rep. ITU-R S.2365-0 161

The Study #1 results of the dynamic analysis for the HIWRAP aeronautical precipitation radar/scatterometer of the Gulf of Mexico are provided in Fig. 9-8 and Table 9-12. This result indicates a maximum interference exceedance level of at least 26.4 dB for the –6 dB I/N criteria for radiolocation services operating over the Gulf of Mexico when considering a FSS deployment FRF of 1.2. The results also indicate that for the analysis examining the operation of HIWRAP over the Gulf of Mexico that the –6 dB I/N criteria is exceeded 0.06% of the time for an FRF of 1.2. The Study #2 results of the dynamic analysis for an area of measurement of interest taken to be that of the Gulf of Mexico are provided in Fig. 9-8. This result indicates an interference level lower of at least 1.5 dB for the –6 dB I/N criteria for radiolocation services. This result of the parametric dynamic analysis shows that the Recommendation ITU-R M.1644 prescribed protection criteria of –6 dB I/N (equivalent to –130 dBW/100 MHz for HIWRAP) is exceeded 0.05% of the time considering a FRF of 1.5. Following the revision of sharing conditions in the band 13.75-14 GHz under WRC-03 AI 1.24, some administrations might have migrated their radiolocation radar systems in the band 13.4-13.75 GHz, in order to limit interference from FSS Earth stations. As the band 13.4-13.75 GHz is used by the same radars as the band 13.75-14 GHz, at a minimum, the provisions existing in the 13.75-14 GHz band should also be applied in the band 13.4-13.75 GHz, and, in particular, the provisions of RR No.5.502.

9.2.5 FSS (E-s and s-E) and SRS 9.2.5.1 SRS characteristics The frequency band 13.4-13.75 GHz is used by data relay satellite (DRS) systems operating in the space research service for forward inter-orbit links (GSO DRS-to-NGSO (usually LEO) user spacecraft) and for return feeder links (GSO DRS-to-earth station). Figure 9-9, taken from Recommendation ITU-R SA.1018, shows a hypothetical reference system representing a DRS system. Recommendations ITU-R SA.1018 and ITU-R SA.1019 contain general descriptions and preferred frequency bands of data relay satellite systems operating SRS. Recommendation ITU-R SA.1414-1 describes the characteristics of DRS systems operated by five administrations including technical characteristics of transmitting DRS space stations, receiving NGSO space stations and receiving earth stations. ITU-R Space Radiocommunication Stations Data Base (version February 2013) contains information on 24 links of GSO DRS space-to-Earth and 10 links of GSO DRS-to-NGSO users’ spacecrafts that operate in the frequency band 13.4-13.75 GHz.

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FIGURE 9-9 Hypothetical Reference system for Data Relay Systems (DRS)

Analyses of sharing in this band have considered the characteristics of the data relay systems of two different administrations. Table 9-15 shows the typical parameters considered in studies for current and future SRS DRS systems.

TABLE 9-15 Technical Parameters used for SRS DRS system cases

DRS system 1 DRS system 2 Parameters DRS Downlink DRS Forward Transmit Space station location 160W, 16W, 95E, 49W 167E Receive Station WSC, USA ISS ISS Satellite Altitude (km) 250-500 km (ISS); 35786 km (DRS) Satellite Inclination (deg) 51.6 degrees (ISS); 0 degrees (DRS) Bandwidth (MHz) 650 61 40 Maximum transmit PSD (dBW/Hz) –49.7 –67.7 –66.6

1 6 MHz was used in the studies however 50 MHz has been implemented on a DRS system in the 13.75-14.0 GHz band. Rep. ITU-R S.2365-0 163

TABLE 9-15 (end)

DRS system 1 DRS system 2 Satellite Antenna pattern S.672 S. 672 S. 672 (Ls = –15/–20) Ground Station Antenna Pattern F.699 – – Tx Station Antenna gain (dBi) 46 52.4 51.8 Rx Station Antenna gain (dBi) 65.5 45.2 40.8/36 Rx Station Temperature (k) 300 825 550 Aggregate Interference Criteria Rec. SA.609 SA. 1155 Aggregate Interference Protection –6 dB –10 dB criteria (Io/No, dB) % time for the protection criteria 0.1% Apportionment of Total interference Rec. ITU-R SA.1743 to FSS

The first study of FSS (E-s) sharing with SRS DRS systems used the characteristics of DRS System 1 given in § 9.2.5.1.1.

9.2.5.2 FSS (E-s) and SRS 9.2.5.2.1 Study 1 9.2.5.2.1.1 Study 1 FSS characteristics Table 9-16 shows the FSS system typical parameters taken from Table 4-1 of this Report. Also assumed for the FSS system is a noise temperature of 300 k for the FSS earth station.

TABLE 9-16 FSS system technical characteristics

Earth Station Antenna size (m) 0.6 1.3 2.8 6 9.1 Transmission Types VSAT VSAT, VSAT, WB, WB, P-P P-P P-P P-P Typical gain (dBi) 37.2 43.9 50.5 57.2 60.5 PSD at antenna port (dBW/Hz) –42 to –59 –42 to –60 –42 to –60 –49 to –60 –49 to –60 Off-axis radiation pattern BO.1213 BO.1213 S.580 S.580 S.580 S.1855 S.1855 Off-axis power limits Rec. ITU-R S.728

9.2.5.2.1.2 Study 1 Interference criteria a) SRS protection criteria The SRS protection criteria are given in Recommendations ITU-R SA.1155 and SA.609. However, for the purpose of this study, despite the fact that SRS allocation is a secondary allocation in this band, if the frequency band is to be considered as shared by both FSS and DRS with equal status, then FSS could be treated as a Category 2 type of interference and the interference from other SRS sources as a Category 1 type of interference as defined in Recommendation ITU-R SA.1743.

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Although Recommendation ITU-R SA.1743 does not give an exact apportionment for Category 1 and 2, if a method similar to the one done in Recommendation ITU-R F.1094 is used, then the apportionment for Category 2 interference is 10% of the total interference. Using this approach of apportioning the interference allocation given in Recommendation ITU-R SA.1743 onto the total aggregate interference allowed under Recommendations ITU-R SA.609/SA.1155, the interference criteria would be: – Io/No criterion = –16 dB for 0.1% time for DRS E-s, s-E cases – Io/No criterion = –20 dB for 0.1% time for DRS s-s cases b) FSS Protection Criteria Based on recommends 3 of Recommendation ITU-R S.1323, for an FSS GSO network the internetwork interference caused by the earth and space station emissions of all other satellite networks operating in the same frequency band, should be responsible for at most 10% of the time allowance for the BER (or C/N value) specified in the short-term performance objectives of the desired network and corresponding to the shortest percentage of time (lowest C/N value). The FSS protection criteria are given in Recommendation ITU-R S.1432. a) that error performance degradation due to interference at frequencies below 30 GHz should be allotted portions of the aggregate interference budget of 32% or 27% of the clear-sky satellite system noise in the following way: b) 25% for other FSS systems for victim systems not practicing frequency re-use; c) 20% for other FSS systems for victim systems practicing frequency re-use; d) 6% for other systems having co-primary status; e) 1% for all other sources of interference. For the purpose of this study, if SRS interference into FSS is treated as having the same status, the Io/No criterion that can be used for FSS is: 1) ‒12.2 dB (which corresponds to 6%), from Recommendation ITU-R S.1432; and 2) 10% of time, from Recommendation ITU-R S.1323.

9.2.5.2.1.3 Study 1 Assumptions used in the analysis Dynamic simulations were carried out in all cases involving interference into SRS satellites from FSS uplinks. The variable aspect of the simulation is the orbital separation of the SRS and FSS satellites along with the following assumptions: 1) A DRS satellite at 49W is assumed. The International Space Station (ISS) is used as a DRS user satellite. 2) A common service area for SRS and FSS earth stations is assumed for worst case analysis. For the purpose of this analysis, the earth stations are assumed to be collocated, that is, within the 1 dB receive contour of the victim satellite. 3) FSS uplinks from their earth stations are assumed to be accessing GSO satellites in a +/- 60 degree GSO arc around the DRS satellite with 3 degree spacing. 4) The minimum orbital separation between SRS and FSS GSO satellite is assumed to be 1 degree. 5) The FSS ES antenna sizes ranging from 60 cm to 2.8 m shown in Table 9-11 are used in the analysis. These antenna sizes represent the VSAT, point –to- point and broadband transmission types. Note that using an antenna larger than 2.4 m will not change the results, as the antenna side lobes would not be further narrowed. 6) For computing the aggregate interference into DRS Forward links from FSS uplinks, all FSS uplink earth station in each simulation are assumed to have the same antenna size and PSD. Rep. ITU-R S.2365-0 165

Multiple results are provided each using a different set of assumed FSS earth station antenna size, location and PSD values. The FSS earth stations are assumed at satellite beam centers (gain = 30 dB) considered at the GSO longitude and at latitudes equal to 0 degrees, 30 degrees and 60 degrees. 7) The FSS power spectral density is assumed to apply for carriers of all bandwidths. SRS and FSS use carriers of different bandwidths and since SRS carriers can be of bandwidth less than the FSS carriers, either single carrier or multicarrier mode, loaded in the transponder, the FSS power density is assumed uniform inside SRS bandwidth. This allows the calculation of Io/No without any bandwidth factor. 8) SRS transmissions occur when the ground station is visible to the SRS satellite. 9) For computing interference from DRS into FSS systems, FSS uplinks are considered for a 60 cm antenna using an uplink PSD of –50 dBW/Hz. However, if the FSS uplinks use alternative values of low PSD, then a detailed C/I analysis is necessary to study the compatibility issues.

9.2.5.2.1.4 Analysis Results Dynamic simulations were carried out assuming that uplink PSD ranges between –42 to –60 dBW/Hz at the input of a 60 cm to 2.8 m FSS earth station antenna. These antenna sizes represent the sizes used by VSAT, Point to Point and broadband services. Earth station sizes larger than 2.0 m would cause the same levels of interference because of the common off-axis pattern. One FSS earth station per FSS satellite is assumed to use the bandwidth used by SRS carriers. The FSS earth stations are assumed at different latitudes (0, 30 deg and 60 deg) and FSS GSO longitudes. Case 1: Interference between DRS downlinks and FSS uplinks a) There could be interference from FSS uplinks into DRS feeder downlinks through a reverse band scenario which requires a minimum coordination distance between DRS feeder downlink stations and FSS uplink earth stations to protect the DRS feeder downlinks. b) Analysis shows that the interference levels from DRS feeder downlinks into FSS uplinks are very low compared to the threshold, for orbital separations more than 1 degree. The FSS earth station is assumed to be at the center of the high gain DRS downlink beam. The results of interference from DRS downlinks into FSS uplinks are shown in Fig. 9-10.

FIGURE 9-10 Interference (Io/No dB, 10% time) from DRS feeder downlinks into FSS uplinks

Case 2: Interference between DRS Forward links and FSS uplinks a) For the case of aggregate interference into DRS Forward links from FSS uplinks, FSS satellites spaced 3 degrees apart in a 60 degree GSO arc (110 W-10 E) around the DRS

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satellite are considered. The closest FSS satellite is assumed to be one degree away from the DRS satellite. FSS earth stations are assumed at the longitudes of GSO satellite and at latitude of 0 deg, 30 deg and 60 deg. The results of aggregate interference from FSS uplinks into DRS forward links are shown in Fig. 9-15. The aggregate interference (in time and levels) from FSS uplinks into a representative DRS user satellite (ISS) is computed considering one earth station per FSS satellite using the same frequency as the SRS forward links. Multiple results of interference into DRS forward links from FSS uplinks using a different set of assumed FSS ES antenna size, PSD values and earth station latitudes of 0 deg and 60 deg are shown in Table 9-17. The interference levels are shown for a minimum separation of 1 degree between FSS and DRS satellites. It is noted that the interference levels are similar even for large separations like 9 degree between the DRS and the nearest FSS satellite. The level of interference (Io/No) into DRS forward links from FSS transmissions using ES at latitudes of 60 degrees and a PSD of –42 dBW/Hz is about 19.6 dB for an ES size of 1.2 m and is 11 dB for larger antennas. The levels of interference caused by using lower PSD for FSS uplinks can be scaled from the above results. It may be noticed in the table that the interference due to 1.2 m is larger than that due to 60 cm when the FSS e/s is at high latitudes. One of the reasons is that, for a given input PSD, the 1.2 m antenna would have more off axis e.i.r.p. density than a 60 cm antenna at angles close to the beam peak. Therefore, the interference from high latitude FSS e/s into a user satellite with high inclination appears to occur more close to e/s beam peak region. The total interference excess into forward links will depend on the noise percentage allocated for FSS interference. Co-frequency sharing is not feasible considering the FSS system characteristics used in the study (see § 9.2.5.2.1.1), including that all FSS earth stations are at the same latitude.

FIGURE 9-11 Interference (Io/No dB) from FSS uplinks into DRS Forward links FSS ES Antenna = 0.6 m to 2.8m , PSD = –42 dBW, FSS ES Lat = 0 and 60 deg

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TABLE 9-17 Results of Interference (Io/No, dB for 0.1% time) from FSS Uplinks into DRS Forward links for 1 degree GSO separation between DRS and FSS satellites

FSS ES Lat: 0 deg/GSO FSS ES Lat: 30 deg/GSO FSS ES Lat: 60 deg/GSO Long Long Long PSD= PSD= PSD= PSD= PSD= PSD= PSD= PSD= PSD= FSS ES –42 –50 –60 –42 –50 –60 –42 –50 –60 .6m 5.0 –3.0 –13.0 6.6 –1.4 –11.4 16.7 8.7 –1.3 1.2m 1.5 –6.5 –16.5 4.0 –4.0 –14.0 19.6 11.6 1.6 3m:>2m –1.0 –9.0 –19.0 1.0 –7.0 –17.0 11.0 3.0 –7.0 b) Analysis shows that the interference from DRS forward links into FSS uplinks is below the threshold as shown in Fig. 9-12.

FIGURE 9-12 Interference (Io/No dB, 10% time) from DRS forward links into FSS uplinks

9.2.5.2.1.5 Study 1 Summary & Conclusion An analysis has been performed to assess the potential for interference between the SRS DRS system 1 and potential FSS (E-s) systems in the 13.4-13.75 GHz band. Considering the same status for FSS and SRS, the following conclusions could be observed for the FSS uplinks: 1) DRS downlink stations would need a minimum coordination distance from the FSS uplink stations on the ground and coordination may be feasible with such measures between FSS uplink and SRS downlink stations. 2) DRS system 1 forward links would receive levels of aggregate interference from FSS uplinks higher than the desired protection criterion under co-frequency situations, exceeding the total aggregate interference criteria by 29.6 dB for the worst case.

9.2.5.2.2 Study 2 The second study of FSS (E-s) sharing with SRS DRS systems forward links used the characteristics of DRS System 1.

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9.2.5.2.2.1 Study 2 FSS characteristics FSS Parameters from Table 4-2 of § 4 of this Report are considered for dynamic analysis.

9.2.5.2.2.2 Study 2 Interference criteria The SRS protection criteria are given in Recommendations ITU-R SA.1155 and SA.609. However, for the purpose of this study, despite the fact that SRS allocation is a secondary allocation in this band, if the frequency band is to be considered as shared by both FSS and DRS with equal status, then FSS could be treated as a Category 2 type of interference and the interference from other SRS sources as a Category 1 type of interference as defined in Recommendation ITU-R SA.1743 which not give an exact apportionment for Category 1 and 2.

9.2.5.2.2.3 Study 2 Assumptions used in the analysis Dynamic simulation was carried out in all cases involving interference into SRS satellites from FSS uplinks. The variable aspect of the simulation is the orbital separation of the SRS and FSS satellites along with the following assumptions: 1) DRS satellite at 0E is assumed. The International Space Station (ISS) is used as a DRS user satellite. 2) FSS uplinks from their earth stations are assumed to be accessing GSO satellites with 3 degree spacing and a minimum elevation angle of 10°. 3) Minimum orbital separation between SRS and the nearest FSS GSO satellite is assumed to be 0 and 1.5 degree. 4) For computing aggregate interference into DRS Forward links from FSS uplinks, the deployment model as developed in § 4 of this Report was used considering a minimum FSS earth station antenna diameter of 1.2 m and an e.i.r.p. of any emission between 68 dBW and 85 dBW for earth stations having an antenna diameter greater than or equal to 4.5 m. 5) According to the FSS deployment model and a study bandwidth of 6 MHz, 335 FSS earth stations (see Table 9-18) have been deployed worldwide (50% according to population density & 50% according to uniform distribution) considering a frequency reuse factor of 1.5.

TABLE 9-18 FSS antenna characteristics used in simulation

9.2.5.2.2.4 Study 2 Analysis Results Interference between DRS Forward links and FSS uplinks For the case of aggregate interference into DRS Forward links from FSS uplinks, FSS satellites spaced 3 degrees apart are considered. The closest FSS satellite is assumed to be at 0 and 1.5 degree Rep. ITU-R S.2365-0 169 away from the DRS satellite. FSS earth stations are assumed to be located according to the FSS deployment model (see § 4) and a Frequency reuse factor of 1.5 was used to derive the total number of FSS earth station. The results of aggregate interference from FSS uplinks into DRS forward links are shown in Fig. 9-13 for both cases. It is noted that the interference levels are similar for separations like 0 and 1.5 degree between the DRS and the nearest FSS satellite. The level of interference (Io/No) into DRS forward links from FSS transmissions respects the aggregate interference protection criteria (Io/No criterion = ‒10 dB for 0.1 % time). Co-frequency sharing is feasible considering the assumptions of this study.

FIGURE 9-13 Interference (Io/No dB) from FSS uplinks into DRS Forward links

9.2.5.2.2.5 Study 2 Summary & Conclusion Analysis has been performed to assess the potential for interference between the SRS DRS system 1 forward links and potential FSS systems in the 13.4-13.75 GHz band in the uplink direction considering the parameters as described above. Considering the same status for FSS and SRS, the following conclusion could be observed for the FSS uplinks: DRS system 1 forward links would not receive levels of aggregate interference from FSS uplinks higher than the desired aggregate protection criterion (I/N of –10 dB for 0.1% of time) under co- frequency situations in case limits imposed by Footnote 5.502 are respected. The responsible ITU-R Working Party for SRS has noted a number of concerns with respect to Study 2. – The simulation performed for this study employed a step size of 10 minutes and a simulation period of 14 days. Considering the dynamic nature of the forward inter-orbit links to NGSO DRS system user satellites, these results cannot be considered to be reliable. Typically for analysis involving DRS inter-orbit links, simulations should be run using smaller time increments (such as 1 second) for a period of one year in order to produce better results – The study in § 9.2.5.2.2 used the protection criteria given in Recommendation ITU-R SA.1155 for the inter-orbit links of DRS systems of –10 dB Io/No to be exceeded no more than 0.1% of the time. As described in § 9.2.5.2.1.2, the SA.1155 criteria specifies the maximum acceptable aggregate interference from all sources, of which, FSS systems would be only one contributor. Accordingly, the apportioned interference criterion of –20 dB Io/No

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to be exceeded no more than 0.1% of the time is the appropriate one to ensure protection of the very sensitive DRS system inter-orbit links. – In comparing the results of this Study with those of Study 1, it is noted that the aggregate interference levels shown in Fig. 9-13 are significantly less than those for the Study 1 results for antenna sizes ≥ 1.2m shown in Fig. 9-11, lower in fact than what would be seen in the Study 1 analysis from a single FSS uplink terminal. Therefore it is uncertain whether the aggregate interference results shown in Fig. 9-13are representative of a realistic situation.

9.2.5.2.3 Summary of Studies for FSS (E-s) and SRS Two studies were performed between FSS (E-s) and SRS DRS system 1 in this band, using different FSS Earth station deployment models, as well as other initial assumptions such. The first study, which employed an apportioned protection criteria as indicated by the relevant ITU-R study group, concluded that sharing between FSS (E-s) and the return feeder links of SRS DRS systems was feasible, but that sharing between FSS (E-s) and DRS forward inter-orbit links was not, with all FSS earth stations located at the same latitude and considering parametrically a range of earth station antenna size (0.6 to 2.4 m) and maximum power spectral density (–42 to –60 dBW/Hz). The second study, which employed the aggregate interference criteria and used FSS earth station location according to deployment model in § 4 reached the opposite result with respect to DRS forward inter- orbit links, concluding that sharing could be feasible subject to regulatory measures/technical limitations (minimum FSS earth station antenna diameter of 1.2 m, e.i.r.p. of any emission limited between 68 dBW and 85 dBW for earth stations having an antenna diameter greater than or equal to 4.5 m). Currently the forward inter-orbit links is not operated under system 1 in this band. However, the responsible Working Party for the SRS Data Relay Satellite systems has indicated that the DRS forward link parameters used in these studies can be considered as representative of those of systems which could be operated by many space agencies, and that the results shown in the analysis conducted within WP 7B therefore represent the situation with not one administration but with many. The results of the interference analysis, considering the same status for FSS and SRS allocations are summarized in Table 9-19.

TABLE 9-19 Summary of results of interference between SRS DRS systems and proposed FSS Uplink allocations in the 13.4-13.75 GHz band

Possible to establish compatibility between SRS and FSS for co-frequency operations? New FSS Frequency FSS interference SRS interference Case SRS (DRS) links allocation band (GHz) into SRS into FSS FSS DRS return feeder link 1 Yes* Yes Uplink (downlink) 13.40-13.75 (AI 1.6.1) DRS forward inter- 2 No Yes orbit link * Coordination between SRS and FSS feasible using measures like: satellite orbital separation, beam separation, ES separation, etc.

Based on the summary table above and considering the assumptions used in the studies, the following can be observed for 13.4-13.75 GHz, FSS uplinks: Rep. ITU-R S.2365-0 171

– Case 1: FSS uplink Earth stations would need a minimum coordination distance from the DRS downlink Earth stations on the ground and coordination may be feasible with such measures between FSS uplink and SRS downlink stations. Provisions of RR No. 9.17A could be applied for coordination of the transmitting FSS Earth stations with receiving SRS Earth stations. Provisions of RR No. 9.7 could be applied for coordination of the transmitting SRS space stations with the receiving FSS space stations. – Case 2: DRS forward links could receive levels of aggregate interference from FSS uplinks higher than the desired protection criterion under co-frequency situations, depending on parameters of the SRS DRS system and limits imposed on potential FSS uplink allocation. As the current DRS forward links are using the band 13.4-13.75 GHz, the band 13.4-13.75 GHz is not available for coordination between SRS and FSS. Compatibility of the FSS uplinks with existing DRS systems forward links under co-frequency situations will not exist unless adequate hard limits for FSS Earth station parameters are specified. Compatibility of the uplinks with respect to the SRS DRS forward links in the band 13.4-13.75 GHz will not be ensured without adequate mitigation techniques which have not been identified. Mitigation techniques as hard limits for FSS Earth station parameters should be translated into the RR. The impact on SRS DRS system 2 forward links from FSS uplinks has not yet been studied. These studies are required to determine compatibility of the FSS uplinks with respect to the SRS DRS forward links in the band 13.4-13.75 GHz.

9.2.5.3 FSS (s-E) and SRS 9.2.5.3.1 DRS System 1 compatibility studies The first three studies of FSS (s-E) sharing with SRS were performed using the DRS system characteristics of DRS System 1, which are given in § 9.2.5.1

9.2.5.3.1.1 Study 1 9.2.5.3.1.1.1 Study 1 FSS Characteristics Table 9-20 shows the FSS system typical parameters taken from Table 4.1 of this Report used for this analysis. Also assumed for the FSS system is a noise temperature of 300 k for the FSS earth station.

TABLE 9-20 FSS system technical characteristics

Satellite Downlink e.i.r.p. spectral density (dBW/Hz) –20 Downlink antenna gain (dBi) 20, 30

9.2.5.3.1.1.2 Study 1 Interference Criteria The interference criteria for this Study are the same as given in § 9.2.5.2.1.2 for the first study in the section on FSS (E-s) sharing with SRS.

9.2.5.3.1.1.3 Study 1 Assumptions Used in the Analysis Dynamic simulations were carried out in all cases involving interference into SRS satellites from FSS uplinks. The variable aspect of the simulation is the orbital separation of the SRS and FSS satellites along with the following assumptions:

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1) A DRS satellite at 49 W is assumed. The International Space Station (ISS) is used as a DRS user satellite. 2) A common service area for SRS and FSS earth stations is assumed for worst case analysis. For the purpose of this analysis, the earth stations are assumed to be collocated, that is, within the 1 dB receive contour of the victim satellite. 3) The minimum orbital separation between SRS and FSS GSO satellite is assumed to be 1 degree. 4) For the case of interference from FSS downlinks, the maximum downlink e.i.r.p. density assumed is –20 dBW/Hz and the FSS satellite antenna gain values of 20 dB and 30 dB are assumed towards a 60 cm antenna at the beam center. 5) The FSS earth stations are assumed at satellite beam centers (gain = 30 dB) considered at the GSO longitude and at latitudes equal to 0 degrees, 30 degrees and 60 degrees. 6) The FSS power spectral density is assumed to apply for carriers of all bandwidths. SRS and FSS use carriers of different bandwidths and since SRS carriers can be of bandwidth less than the FSS carriers, either single carrier or multicarrier mode, loaded in the transponder, the FSS power density is assumed uniform inside SRS bandwidth. This allows the calculation of Io/No without any bandwidth factor. 6) SRS transmissions occur when the ground station is visible to the SRS satellite.

9.2.5.3.1.1.4 Study 1 Analysis Results Dynamic simulation is carried out assuming the FSS satellite beam gain of 20 dB and 30 dB and a downlink e.i.r.p. density of –20 dBW/Hz. Case 1: Interference between DRS downlinks and FSS downlinks a) The results of interference from FSS downlinks into DRS downlinks for varying orbital separation and FSS satellite gains are shown in Fig. 9-14. The results show that the Io/No level is about 8 dB for 1 degree orbital separation between FSS and DRS satellites assuming collocated earth station locations. Coordination is feasible using standard coordination measures like earth station contour advantage.

FIGURE 9-14 Interference (Io/No dB, 0.1% time) from FSS downlinks into DRS downlinks

b) The results of interference from DRS downlinks into FSS downlinks for varying orbital separation and FSS satellite gains are shown in Fig. 9-15. The results show that the Io/No Rep. ITU-R S.2365-0 173

level exceeds 25 dB for 1 degree orbital separation between FSS and DRS satellites assuming collocated earth station locations and a 60 cm FSS antenna. Coordination is feasible using standard coordination measures like earth station contour advantage, sufficient orbital separation, better antenna side lobes, etc.

FIGURE 9-15 Interference (Io/No dB) from DRS downlinks into FSS downlinks

Case 2: Interference between DRS Forward links and FSS downlinks a) The SRS user satellite can be seen by many FSS satellites downlinking to the Earth, while it is communicating to the DRS. For analysis purposes, FSS satellites in the GSO arc spaced 3 degrees apart around the DRS satellite and downlinking with a maximum e.i.r.p. density of –20 dBW/Hz towards the Earth are considered. GSO satellites in a 60 degree GSO arc (110 W-10 E) around the DRS satellite are considered while interference can arise from FSS satellite downlinks even outside this arc. The closest FSS satellite is assumed to be one degree away from the DRS satellite. FSS earth stations are assumed at the longitude corresponding to FSS satellite and a latitude of 0 deg, 30 deg and 60 deg. The aggregate interference from FSS downlinks into a representative DRS user satellite shown in Fig. 9-16 is computed considering the FSS satellite antenna patterns over the SRS user satellite trajectory. The worst case results of aggregate interference from FSS downlinks into DRS forward links are shown in Fig. 9-12 for an FSS orbital separation of 3 degrees. The aggregate interference (Io/No level) from the FSS satellites in the arc 110 W-10 E is 1 dB assuming a minimum GSO separation of 1 degree between the DRS and the nearest FSS satellite. The actual interference excess into DRS forward links will depend on the percentage allocated for FSS interference. Co-frequency sharing is not feasible under existing assumptions but may be achievable using mitigation techniques which may include increasing orbital separation and/or reducing e.i.r.p. of the FSS satellites.

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FIGURE 9-16 Aggregate Interference (Io/No dB) from FSS downlinks into DRS Forward links (40 FSS satellites with 3 degree spacing in the arc 110W to 10E Nearest FSS satellite 1 degree away from DRS satellite)

b) Analysis shows that the interference from DRS forward links into FSS downlinks is below the threshold even for an orbital separation of 1 degree as shown in Fig. 9-17.

FIGURE 9-17 Interference (Io/No dB, 10% time) from DRS forward links into FSS downlinks

9.2.5.3.1.1.5 Study 1 Summary and Conclusion An analysis has been performed to assess the potential for interference between the SRS DRS system 1 and potential FSS systems in the 13.4-13.75 GHz band. Considering the same status for FSS and SRS, the following conclusions could be observed for the FSS downlinks: (1) The mutual interference between DRS downlinks and FSS downlinks would exceed the protection criterion, assuming worst case condition like the FSS earth station being collocated with the DRS earth station. However, coordination measures like setting a minimum orbital separation between the GSO satellites, beam separation advantage for earth station locations and possibly other measures could considerably reduce the interference. (2) DRS forward links would receive interference from FSS downlinks higher than the desired protection criterion, under co-frequency situations assuming a minimum GSO separation of 1 degree between the DRS and the nearest FSS satellite. Rep. ITU-R S.2365-0 175

Compatibility between SRS and FSS (s-E) may be achievable in 13.4-13.75 GHz band using regulatory provisions and technical measures like setting minimum orbital separation between the DRS satellite and the nearest FSS satellite and limiting the e.i.r.p. density of the FSS downlinks

9.2.5.3.1.2 Study 2 The second study of FSS (s-E) sharing with SRS builds upon the results of Study 1 detailed in § 9.2.5.3.1.1. It observes that two different classes of SRS/DRS are identified in Study 1: links from a GSO to an SRS receiving earth station (“DRS downlinks”), and links from a GSO to a non-GSO receiving space station (“DRS forward links”). Moreover, it notes that the results of Study 1 reflect that: – DRS downlinks are compatible provided sufficient orbital separation is achieved between the SRS/DRS and the FSS satellites; – DRS forward links may be compatible with aggregate FSS satellite interference, assuming FSS satellites were located every 3 degrees in the GSO arc, subject to a minimum separation between the SRS/DRS satellite and the closest FSS satellite; – Interference from the SRS/DRS into the FSS should meet the FSS protection criteria in all cases.

9.2.5.3.1.2.1 Study 2: Further development of FSS (s-E) and SRS Studies Reviewing the assumptions made in Study 1 reveals that some small changes may significantly improve the compatibility between the SRS and FSS. In particular, the minimum orbit separation of 1° between an SRS and an FSS satellite may result in a pessimistic result; typically, co-frequency co-coverage FSS systems operate at minimum orbital spacings of at least 2°-3°. Furthermore, the minimum FSS earth station diameter of 0.6 m assumes a very high-power downlink; given that an assignment in the 13.4-13.75 GHz band would require isolation from any Earth-to-space assignment (in the 13.75-14.5 GHz band) on the same satellite, it may be unrealistic to assume that such a very high-power downlink would be operated in this allocation. (Further consideration of the isolation issue is considered in the conclusions).

9.2.5.3.1.2.2 Study 2: Assumptions Used in the Study The assumptions used in Study 2 are the same as those for Study 1 detailed in § 9.2.5.3.1.2.3 with the exception of the following: – A minimum orbital separation of 3 degrees between GSO FSS and GSO DRS spacecraft is also considered. – The case of an FSS downlink e.i.r.p. density of –26 dBW/Hz towards an FSS earth station antenna of 1.2 m was also considered. The non-GSO SRS DRS user-satellite receiving antenna is assumed to have a standard off- axis envelope of 29-25log(φ), applicable for the FSS earth stations. 9.2.5.3.1.2.3 Study 2: Analysis Results Results of this study are presented below for the Cases considered in § 9.2.5.3.1.1.3. Case 1: Interference between DRS downlinks and FSS downlinks a) The results of Study 1 analysis of interference from FSS downlinks into DRS downlinks for varying orbital separation and FSS satellite gains are shown in Fig. 9-14. The results show that the Io/No level is about 8 dB for 1 degree orbital separation between FSS and DRS satellites assuming collocated earth station locations. However, by reducing the maximum FSS downlink power by 6 dB (to –26dBW/MHz), the Io/No level is about 2 dB for 1 degree

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orbital separation, and –16 dB for 3 degrees. Coordination is therefore feasible using standard coordination measures. b) The results of interference from DRS downlinks into FSS downlinks for varying orbital separation and FSS satellite gains are shown in Fig. 9-15. The results show that the Io/No level exceeds 25 dB for 1 degree orbital separation between FSS and DRS satellites assuming collocated earth station locations and a 60 cm FSS antenna. Coordination is feasible using standard coordination measures like earth station contour advantage, sufficient orbital separation, better antenna side lobes, etc. Case 2: Interference between DRS Forward links and FSS downlinks a) For the Study 1 simulations, the closest FSS satellite is assumed to be one degree away from the DRS satellite. The worst case results of aggregate interference from FSS downlinks into DRS forward links are shown in Fig. 9-16 above for an orbital separation of 3 degrees between FSS satellites. The aggregate interference (Io/No level) from the FSS satellites in the arc 110 W-10 E is 1 dB assuming a minimum GSO separation of 1 degree between the DRS and the nearest FSS satellite; this is reduced to –10 dB2 if the closest FSS satellite is assumed to be 3 degrees away from the DRS. The actual interference excess into DRS forward links will depend on the percentage allocated for FSS interference. Co-frequency sharing is therefore feasible provided that sufficient minimum orbital separation and/or a reduction in e.i.r.p. of the FSS satellites is achieved.

9.2.5.3.1.2.4 Study 2: Conclusions Based on the results in Study 1 as modified in the analysis above and the assumptions of the study, the following can be observed for 13.4-13.75 GHz, FSS downlinks: The mutual interference between DRS downlinks and FSS downlinks may exceed the protection criterion, assuming worst case conditions. However, standard coordination measures like setting a minimum orbital separation between the GSO satellites, beam separation advantage for earth station locations and other measures would considerably reduce the interference and achieve the protection criteria for DRS and FSS. 2) DRS forward links would be protected from harmful interference from FSS downlinks assuming a minimum GSO separation of 3 degrees between the DRS and the nearest FSS satellite. Therefore, considering the results provided above it can be concluded that compatibility between a new FSS space-to-Earth allocation and the existing SRS allocation at 13.4-13.75 GHz can be achieved with some constraints on a case-by-case basis. One possible example of such constraints may be: – Limiting downlink FSS power flux density, and – Maintaining a minimum orbital separation of at least 3° between co-frequency / co-coverage FSS and DRS satellites. Following a standard off-axis envelope of 29-25log(φ) for the non-GSO SRS DRS user-satellite receiving antenna. Further, to ensure compatibility with the FSS uplink allocation beginning at 13.75 GHz, the space-to-Earth allocation can be limited to 13.4-13.65 GHz whilst still achieving the objective of 250 MHz given in Resolution 151 (WRC-12).

2 Assuming off-axis gain envelope of 29-25 log(φ) for the non-GSO SRS DRS user-satellite receiving antenna, increasing the off-axis angle from 1° to 3° reduces aggregate interference by 11 dB. Rep. ITU-R S.2365-0 177

9.2.5.3.1.3 Study 3 9.2.5.3.1.3.1 Study 3 FSS Characteristics Table 9-21 shows the FSS downlink system typical parameters taken from Table 4-1 of this Report. FSS parameters from Table 4-2 of this Report are considered for dynamic analysis. Also assumed for the FSS system is a noise temperature of 300 k for the FSS earth station.

TABLE 9-21 FSS downlink system technical characteristics

Satellite Downlink e.i.r.p. spectral density (dBW/Hz) –20

9.2.5.3.1.3.2 Study 3 Interference Criteria The SRS protection criteria are given in Recommendations ITU-R SA.1155 and SA.609. However, for the purpose of this study, despite the fact that SRS allocation is a secondary allocation in this band, if the frequency band is to be considered as shared by both FSS and DRS with equal status, then FSS could be treated as a Category 2 type of interference and the interference from other SRS sources as a Category 1 type of interference as defined in Recommendation ITU-R SA.1743 which not give an exact apportionment for Category 1 and 2.

9.2.5.3.1.3.3 Study 3 Assumptions Dynamic simulation was carried out in all cases involving interference into SRS satellites from FSS uplinks. The variable aspect of the simulation is the orbital separation of the SRS and FSS satellites along with the following assumptions: 1) DRS satellite at 0E is assumed. The International Space Station (ISS) is used as a DRS user satellite. 3) Minimum orbital separation between SRS and FSS GSO satellite is assumed to be 3.05 degrees. 4) For the case of interference from FSS downlink, the maximum downlink e.i.r.p. density assumed is –20 dBW/Hz with visible Earth global coverage 5) The FSS power spectral density is assumed to apply for carriers of all bandwidths. SRS and FSS use carriers of different bandwidths and since SRS carriers can be of bandwidth less than the FSS carriers, either single carrier or multicarrier mode, loaded in the transponder, the FSS power density is assumed uniform inside SRS bandwidth. This allows the calculation of Io/No without any bandwidth factor.

9.2.5.3.1.3.4 Study 3 Analysis Results Dynamic simulation is carried out assuming the FSS satellite beam has global coverage with a downlink e.i.r.p. density of –20 dBW/Hz. Interference between DRS forward links and FSS downlinks The SRS user satellite can be seen by many FSS satellites downlinking to the Earth, while it is communicating to the DRS. For analysis purposes, one FSS satellite in the GSO arc is considered around the DRS satellite and downlinking with a maximum e.i.r.p. density of –20 dBW/Hz towards the Earth. The orbital separation between the FSS satellite and the DRS satellite is varied to evaluate the I/N value observed. The results of single-entry interference from FSS downlink into DRS forward links are shown in Fig. 9-18 for different FSS GSO – DRS GSO orbital separation. The minimum

178 Rep. ITU-R S.2365-0 orbital separation between DRS satellite and FSS satellite is equal 3.15°in order to meet the aggregate interference criteria (Io/No level= – 10 dB in 0.1 % of time).

FIGURE 9-18 Interference (Io/No dB) from single FSS GSO satellite downlink into DRS Forward links for different FSS GSO – DRS GSO orbital separation

9.2.5.3.1.3.5 Study 3 Summary and Conclusion Analysis has been performed to assess the potential for interference between the SRS DRS system 1 forward links and potential FSS system downlinks in the 13.4-13.75 GHz band considering parameters as described above. Considering the same status for FSS and SRS, the following conclusions could be observed for the FSS downlinks: 1) DRS system 1 forward links would not receive interference from single FSS satellite downlink higher than the desired protection criterion (Io/No level= – 10 dB in 0.1% of time), under co-frequency situations assuming a minimum GSO separation of 3.15 degrees between the DRS and single FSS satellite. Compatibility between SRS and FSS (s-E) is achievable in 13.4-13.75 GHz band using technical/regulatory measures.

9.2.5.3.2 DRS System 2 Compatibility studies The fourth study of FSS (s-E) sharing with SRS was performed using the DRS system 2 characteristics , which are given in § 9.2.5.1.

9.2.5.3.2.1 Study 4 Results of the above interference between SRS DRS system 2 and proposed FSS downlink allocations in the 13.4-13.75 GHz band are that compatibility between SRS and FSS (space-to-Earth) may be achievable in 13.4-13.75 GHz band using mitigation techniques which may include increasing orbital separation and/or reducing e.i.r.p. of the FSS satellites. Further studies could be required to clarify minimum orbital separation between DRS satellite and nearest FSS satellite and other technical measures required in order to meet the aggregate interference criteria (Io/No level= –10 dB in 0.1% of time). Rep. ITU-R S.2365-0 179

In order to determine the minimum orbital separation between the nearest FSS space station (SS) and DRS SS in SRS and also FSS SS e.i.r.p. a dynamic analysis was conducted for different operation parameters of the considered services. This analysis, using the parameters of DRS System 2 documented in § 9.2.5.1, is documented in Study 4.

9.2.5.3.2.1.1 Study 4 Initial Data The characteristics of FSS SS in the range 10-17 GHz are given in § 4 of this Report. The protection criterion for SRS systems is provided in Recommendation ITU-R SA.1155 and given in Table 9-22.

TABLE 9-22 Protection criteria

I0/N0 Data relay satellite link Receiver location (dB) Forward inter-orbit link User spacecraft 13.4-13.75 GHz –10

9.2.5.3.2.1.2 Study 4 Simulation Parameters In the dynamic analysis the following model was used: FSS: − central carrier frequency 13.528 GHz; − interfering FSS SS are located on GSO arc spaced by 3 degrees and use the global beams; − the maximum e.i.r.p. spectral density of each FSS SS on GSO is limited to –20 dB(W/Hz), –23 dB(W/Hz), –25.5 dB(W/Hz) and –31 dB(W/Hz). The permissible pfd levels created by GSO FSS satellite at the Earth’s surface are defined in Fig. 9-3: –137.5/–122 dB (W/m2 1MHz)) for the corresponding elevation angles to provide protection for receiving stations of radiodetermination services. The pfd mask given in Fig. 9-19 below with recalculation of the off-nadir FSS SS antenna angle was taken into account in the compatibility assessment of FSS and SRS:

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FIGURE 9-19 Emission mask of FSS SS for different maximum e.i.r.p. values

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 0 -1 -2 FSS emission mask for max. EIRP=-20 dBW/Hz -3 -4 FSS emission mask for -5 max. EIRP=-23 dBW/Hz -6 FSS emission mask for -7 max. EIRP=-25.5 dBW/Hz -8 FSS emission mask for -9 max. EIRP=-31 dBW/Hz -10 -11 Earth visibility -12 -13 -14

-15 relative EIRP EIRP relative spectral density attenuation, dB -16 -17 -18 off-axis angle, deg.

SRS: − SRS victim receiver is located onboard ISS (orbit parameters: the height above the Earth’s surface is 430 km, orbit inclination 51.668 degrees); − central receiving frequency 13.528 GHz; − two receiving antennas of NGSO user in SRS DRS system: 0.65 m and 1.2 m as shown in Figs 9-20 and 9-21; − the receiving antenna pattern of 0.65 m is in accordance with Recommendation ITU-R S.672 (the first sidelobe suppression is 15 dB):

FIGURE 9-20 Antenna pattern of 0.65 m (NGSO user)

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− antenna pattern of 1.2 m is in accordance with Recommendation ITU-R S.672 (the first sidelobe suppression is 20 dB):

FIGURE 9-21 Antenna pattern of 1.2 m (NGSO user)

Simulation period: 30 days, simulation step 30 s.

9.2.5.3.2.1.3 Study 4 Simulation Results The simulation results of compatibility between FSS (s-E) and SRS (s-s) for the case of NGSO DRS user antenna size of 0.65 m are given in Fig. 9-22.

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FIGURE 9-22 Simulation results of interference scenario for NGSO DRS user antenna of 0.65 m FSS-SRS 13(21deg) 0.65m EIRP -20+mask : Statistics Plot 100 100

10 10

1 TYPE 1.Return.I/N

0.1

Percentage of time,% of Percentage

0.1 0.01

0.001 0.01 -16 -15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 I/N, dB I/N, dB

e.i.r.p. ‒20 dB(W/Hz), orb.sep. 21º e.i.r.p. ‒23 dB(W/Hz), orb.sep. 17º

100 100

10 10

1 1

Percentage of time,% of Percentage

0.1 0.1

0.01 0.01 -15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 I/N, dB I/N, dB

e.i.r.p. ‒25.5 dB(W/Hz), orb.sep. 14º e.i.r.p. ‒31 dB(W/Hz), orb.sep. 8º The simulation results of compatibility between FSS (s-E) and SRS (s-s) for the case of NGSO DRS user antenna size of 1.2 m are given in Fig. 9-23. Rep. ITU-R S.2365-0 183

FIGURE 9-23 Simulation results of interference scenario for NGSO DRS user antenna of 1.2 m

100 100

0.1

Percentage of time,% of Percentage

0.1

0.01

0.01 0.001 -17 -16 -15 -14 -13 -12 -11 -10 -9 -17.4-8 -7 -15.9 -14.4 -12.9 -11.5 -10.0 -8.5 -7.0 I/N, dB I/N, dB

e.i.r.p. ‒20 dB(W/Hz), orb.sep. 10.5º e.i.r.p. ‒23 dB(W/Hz), orb.sep. 8.5º FSS-SRS 13(3-4deg) EIRP -30+mask : Statistics Plot

100 100

1 TYPE 1.Return.I/N

0.1

Percentage of time,% of Percentage

0.1

0.01

0.01 -15 -14 -13 -12 -11 -10 -9 0.001 -8 -7 -6 -5 -15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 I/N, dB I/N, dB

e.i.r.p. ‒25.5 dB(W/Hz), orb.sep. 6.5º e.i.r.p. ‒31 dB(W/Hz), orb.sep. 3º 9.2.5.3.2.1.4 Study 4 Conclusions The results of the analysis considering the parameters of the existing DRS SRS system operating in the frequency band 13.508-13.548 GHz showed that the minimum orbital separation between the nearest FSS SS and DRS SRS SS when the existing aggregate interference criterion is met (the excess of Io/No = –10 dB at not more than 0.1% of time) varies from 3 to 21 degrees depending on the receiving antenna type of NGSO user-satellite and FSS satellites maximum e.i.r.p. spectral density limit. See Table 9-23.

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TABLE 9-23 Minimum orbital separation between the nearest FSS SS and SRS DRS SS

e.i.r.p. spectral density limit of FSS satellites, dB(W/Hz) Antenna pattern type –31 –25.5 –23 –20 of NGSO satellite user D=0.65m, Rec. S.6724; 8 14 17 21 Ls ‒15 dB D=1.2m, Rec. S.672; 3 6.5 8.5 10.5 Ls ‒20 dB

2. In general case the minimum orbital separation between the nearest FSS SS and SRS DRS SS, operating in the frequency band 13.4-13.75 GHz, can vary depending on the limits imposed on FSS space station parameters (maximum e.i.r.p. value, antenna pattern, orbital separation between FSS SS) and SRS DRS system parameters (receiving antenna pattern of NGSO user-satellite, receiving system equivalent noise temperature, etc.). 3. Implementation of the existing provisions of RR Article 9 for compatibility between FSS systems and the operating SRS DRS systems will allow determining the required limitations for protection of the SRS DRS systems on a case by case basis.

9.2.5.3.3 Summary of Studies for FSS (s-E) and SRS Three studies were performed between FSS (s-E) and SRS DRS system 1 in this band and one study was performed between FSS (s-E) and SRS DRS system 2. The results of the interference analysis, considering the same status for FSS and SRS allocations are summarized in Table 9-24.

TABLE 9-24 Summary of results of interference between SRS DRS systems and proposed FSS Downlink allocations in the 13.4-13.75 GHz band

Possible to establish compatibility between SRS and FSS for co-frequency operations? New Frequency FSS interference SRS interference Case SRS (DRS) links allocation band (GHz) into SRS into FSS FSS DRS return feeder 1 Yes* Yes* Downlink link (downlink) 13.40-13.75 (AI 1.6.1) DRS forward 2 Yes** Yes inter-orbit link * Coordination between SRS and FSS feasible using measures like: satellite orbital separation, beam separation, ES separation, etc. ** Compatibility between SRS and FSS may be achievable using mitigation techniques which may include increasing minimum orbital separation and/or reducing e.i.r.p. of the FSS satellites.

Based on the summary table above and considering the assumptions used in the studies the following can be observed for 13.4-13.75 GHz, FSS downlinks: Rep. ITU-R S.2365-0 185

– Case 1: The mutual interference between DRS downlinks and FSS downlinks would exceed the protection criterion, assuming the worst case condition. However, coordination measures like setting a minimum orbital separation between the GSO satellites, beam separation advantage for earth station locations and other measures could considerably reduce the interference and achieve the protection criteria for SRS DRS systems. Case 2 : The minimum orbital separation at the GSO between the SRS DRS space station and the nearest FSS space station could be not less than (3/21) degrees depending on the parameters of the SRS DRS and FSS systems (see Table 9-23). To ensure the required minimum orbital separation, frequency assignments of the GSO FSS networks in the 13.4-13.75 GHz band shall be subject to coordination with respect to existing DRS systems in the space research service (space-to-space). Compatibility between SRS and FSS (space-to-Earth) may be achievable in 13.4-13.75 GHz band applying regulatory provisions (as for example application of the 9.7, 9.21 RR) and technical measures like setting minimum orbital separation at the GSO between the SRS DRS space station and the nearest FSS space station and limiting maximum e.i.r.p. spectral density for FSS downlinks. Further, to ensure compatibility with the FSS uplink allocation beginning at 13.75 GHz, the space- to-Earth allocation can be limited to 13.4-13.65 GHz whilst still achieving the objective of 250 MHz given in Resolution 151 (WRC-12).

9.2.6 FSS (E-s and s-E) Standard frequency and time signal-satellite (Earth-to-space) 9.2.6.1 Characteristics of ACES The characteristics of the ACES system are provided Document 4A/127. They are reproduced in Table 9-25. The spaceborne receiver is located on the International Space Station (ISS).

TABLE 9-25 Characteristics of Standard frequency and time signal-satellite (Earth-to-space) systems in the band 13.4-13.75 GHz

Parameter Value Frequency band 13.4-13.75 GHz Center frequency 13.475 GHz Occupied bandwidth 125 MHz E/S emission power 3 dBW Maximum E/S power spectral density –79.5 dBW/Hz E/S Feeder loss 1.5 dB Maximum E/S antenna gain 32 dBi Spacecraft receiver noise temperature 730 K Spacecraft antenna gain +6.5 dBic max. to 0.2 dBic for ±70° Polarization LHCP Protection criteria Recommendations ITU-R SA.609 and ITU-R SA.1743 Recommendation ITU-R SA.609 recommends a protection level of –177 dBW/kHz to be exceeded less than 0.1% of the time. This is based on an I/N of –6 dB. Keeping this I/N ratio and considering a band of 125 MHz with a noise temperature of 730 K and no apportionment would lead to a protection level of –125 dBW in 125 MHz.

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9.2.6.2 Dynamic simulation #1 According to the deployment model used and a frequency reuse factor of 1.2, 5,045 FSS Earth stations have been deployed worldwide in a frequency band of 125 MHz (see Fig. 9-24). Each FSS Earth station is pointing to one GSO satellite chosen randomly between a total of 120 GSO satellites, one each 3 degrees, provided that a minimum elevation angle of 10° is respected. Table 9-26 is an embedded excel file which contains all formula.

FIGURE 9-24 Location of the 5,045 FSS Earth stations

TABLE 9-26 FSS antenna characteristics used in simulations for ESA system ACES (specific ES characteristics deployment model)

FSS2 Data Nyquist Average Power Occupied Bandwidth allocated Antenna Diameter % of total Average Tx Number of bandwidth Density bandwidth to each type of Type (m) Bandwidth Power (dBW) antenna (MHz) (dBW/Hz) (MHz) antenna (MHz) Type 1 0.6 2.2 0.3% -55 8.4 2.64 54 20 Type 2 1 0.6 9.4% -53.8 4.0 0.72 1692 2350 Type 3 1.5 0.5 3.4% -56.1 0.9 0.6 612 1020 Type 4 2.1 4.5 35.2% -56.8 9.7 5.4 6336 1173 Type 5 3.5 26.2 8.7% -54.8 19.4 31.44 1566 50 Type 6 7 23.9 26.3% -59.9 13.9 28.68 4734 165 Type 7 10 9.4 16.7% -67.6 2.1 11.28 3006 266 Total 5045

The ESA system ACES orbits are simulated during 17 days with a time step of 1 minute. The pattern given in Fig. 9-25 was considered for ACES. Rep. ITU-R S.2365-0 187

FIGURE 9-25 ACES antenna pattern

FIGURE 9-26 Cdf of interference received on ESA system ACES (specific ES characteristics deployment model)

As shown in Fig. 9-26, the 5,045 FSS earth stations create an interference level of –124.5 dBW for 0.1% of the time, therefore exceeding the protection criterion by 0.5 dB. For these simulations, an FSS transponder with a bandwidth of 125 MHz is assumed (worst case situation). In practice, based on the type of service offered, these 125 MHz could be split in 4 transponders of 26 MHz or 3 transponders of 36 MHz or 2 transponders of 54 MHz or a mix. Therefore, due to the required guard band between transponders, in any case the occupied bandwidth will be lower than 125 MHz, around 100/110 MHz. Therefore, if we consider 4 transponders of 26 MHz, the occupied bandwidth will be equal to 104 MHz and the maximum number of FSS Earth station which could be deployed worldwide will be equal to only 4,198, which represent a reduction of around 17% of the total number of Earth station considered in these simulations. In order to perform a simulation, 4,198 FSS Earth stations have been deployed worldwide in a frequency band of 125 MHz (see Fig. 9-27). Each FSS Earth station is pointing to one GSO satellite chosen randomly between a total of 120 GSO satellites, one each 3 degrees, provided that a minimum elevation angle of 10° is respected. Table 9-27 is an embedded excel file which contains all formula.

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FIGURE 9-27 Location of the 4,198 FSS Earth stations

TABLE 9-27 FSS antenna characteristics used in simulations for ESA system ACES (Tpxs 26 MHz)

FSS2 Data Nyquist Average Power Occupied Bandwidth allocated Antenna Diameter % of total Average Tx Number of bandwidth Density bandwidth to each type of Type (m) Bandwidth Power (dBW) antenna (MHz) (dBW/Hz) (MHz) antenna (MHz) Type 1 0.6 2.2 0.3% -55 8.4 2.64 44.928 17 Type 2 1 0.6 9.4% -53.8 4.0 0.72 1407.744 1955 Type 3 1.5 0.5 3.4% -56.1 0.9 0.6 509.184 849 Type 4 2.1 4.5 35.2% -56.8 9.7 5.4 5271.552 976 Type 5 3.5 26.2 8.7% -54.8 19.4 31.44 1302.912 41 Type 6 7 23.9 26.3% -59.9 13.9 28.68 3938.688 137 Type 7 10 9.4 16.7% -67.6 2.1 11.28 2500.992 222 Total 4198

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FIGURE 9-28 Cdf of interference received on ESA system ACES (Txps 26 MHz)

Summary of dynamic analysis #1 As shown in Fig. 9-28, the 4,198 FSS Earth stations create an interference level of –125.4 dBW for 0.1% of the time in ACES receiver, therefore not exceeding the protection criterion of –125 dBW/125 MHz by 0.4 dB.

9.2.6.3 Dynamic analysis #2 According to the deployment model used, 10 650FSS Earth stations have been deployed worldwide in a frequency band of 125 MHz (see Fig. 9-29). Each FSS Earth station is pointing to one GSO satellite chosen randomly between a total of 120 GSO satellites, one each 3 degrees, provided that a minimum elevation angle of 10 degrees is respected.

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FIGURE 9-29 Location of the 10 650 FSS Earth stations

TABLE 9-28 FSS antenna characteristics used in simulations for ESA system ACES (Worst case)

Number of Number of Number of Transmissions Transmission Percentage of Total Transmissions in Transmissions in in EESS Type Satellite Transmissions 500 MHz per EESS bandwidth bandwidth for satellite per satellite 120 satellites VSAT 69.30% 246 62 7380 Wideband 4.90% 17 4 510 Point-to-Point 25.80% 92 23 2760 All 100% 355 89 10650

The ESA system ACES orbits are simulated during 1 day with a time step of 1 second. The pattern given in Fig. 9-30 was considered for ACES. Rep. ITU-R S.2365-0 191

FIGURE 9-30 ACES antenna pattern

FIGURE 9-31 Cdf of interference received on ESA system ACES

Summary of dynamic analysis #2 As shown in Fig. 9-31, the 10 650 FSS earth stations create an interference level of –117.4 dBW for 0.1% of the time, therefore exceeding the protection criterion by 7.6 dB.

9.2.6.4 Dynamic analysis #3 9.2.6.4.1 Approach Similar approach was used as for the sharing analysis #7 with EESS (active) (see § 8.2.1.11.5)

9.2.6.4.2 FSS (E-s) allocation strategy and deployment model Similar allocation strategy and deployment model were used as for the sharing analysis #7 with EESS (active) (see § 8.2.1.15.5.2).

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9.2.6.4.3 ACES simulation results 9.2.6.4.3.1 Cumulative analysis with specific ES characteristics deployment model In this simulation, 4 071 FSS Earth stations have been deployed worldwide (50% according to population density & 50% according to uniform distribution) in a frequency band of 125 MHz (see Table 9-29). Each FSS Earth station is pointing to one GSO satellite chosen randomly between a total of 120 GSO satellites, one each 3 degrees, provided that a minimum elevation angle of 10° is respected.

TABLE 9-29 FSS antenna characteristics used in simulations ESA system ACES (specific ES characteristics deployment model)

The ESA system ACES orbits are simulated during 17 days with a time step of 1 minute. As shown in Fig. 9-32, the 4 071 FSS Earth stations create an interference level of –128 dBW for 0.1% of the time in ACES receiver, therefore not exceeding the protection criterion of –125 dBW/125 MHz by 3 dB.

FIGURE 9-32 Cdf of interference received on ACES (specific ES characteristics deployment model)

9.2.6.4.3.2 Cumulative analysis with identical ES characteristics deployment scenario Simulations performed in this section, considered that all FSS (E-s) terminal will be only 60 cm VSAT terminal and will use respectively power spectral density equal to –42 dBW/Hz, –50 dBW/Hz and –55 dBW/Hz as defined for single entry calculation in § 4 of this Report. Rep. ITU-R S.2365-0 193

Considering a carrier bandwidth of 600 kHz, 22 500 FSS Earth stations have been deployed worldwide (50% according to population density & 50% according to uniform distribution) in a frequency band of 125 MHz (see Table 9-30). Each FSS Earth station is pointing to one GSO satellite chosen randomly between a total of 120 GSO satellites, one each 3 degrees, provided that a minimum elevation angle of 10° is respected.

TABLE 9-30 FSS antenna characteristics used in simulations for altimeters

ACES orbits are simulated during 17 days with a time step of 1 minute. Figures 9-33 to 9-35contain results of these simulations with 22 500 FSS Earth stations. As shown in the Figure below, the 22 500 FSS Earth stations with an antenna diameter of 60 cm and a power spectral density equal to –42 dBW/Hz create an interference level of –113 dBW for 0.1% of the time in ACES receiver, therefore exceeding the protection criterion of –125 dBW/125 MHz by 12 dB.

FIGURE 9-33 Cdf of interference received on ACES (identical ES characteristics deployment with 60 cm –42 dBW/Hz)

As shown in Fig. 9-34, the 22 500 FSS Earth stations with an antenna diameter of 60 cm and a power spectral density equal to –50 dBW/Hz create an interference level of –122 dBW for 0.1% of the time in ACES receiver, therefore exceeding the protection criterion of –125 dBW/125 MHz by 3 dB.

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FIGURE 9-34 Cdf of interference received on ESA system ACES (identical ES characteristics deployment with 60 cm –50 dBW/Hz)

As shown in Fig. 9-35, the 22 500 FSS Earth stations with an antenna diameter of 60 cm and a power spectral density equal to –55 dBW/Hz create an interference level of –126.5 dBW for 0.1% of the time in ACES receiver, therefore not exceeding the protection criterion of –125 dBW/125 MHz by more than 1.5 dB.

FIGURE 9-35 Cdf of interference received on ESA system ACES (identical ES characteristics deployment model with 60 cm –55 dBW/Hz)

9.2.6.4.4 Summary of dynamic analysis #3 An overview of results obtained for all simulations is reproduced in Table 9-31 below. Rep. ITU-R S.2365-0 195

TABLE 9-31 Simulations result overview for ESA system ACES

SENTINEL-3

Interference level Exceedence margin of Simulation scenario (dBW/125 MHz) interference criteria (dB)

Specific ES characteristics deployment model –128 –3 Identical ES characteristics deployment model –113 +12 with 60 cm and –42 dBW/Hz Identical ES characteristics deployment model –122 +3 with 60 cm and –50 dBW/Hz Identical ES characteristics deployment model –126.5 –1.5 with 60 cm and –55 dBW/Hz

As shown in Table 9-31, a new FSS (E-s) allocation in the band 13.25-13.75 GHz with regard Standard Frequency and Time Signal Service is compatible without FSS (E-s) parameters restriction considering a deployment model with specific parameters for each ES. It is also compatible considering the deployment scenario in this particular study with all Earth stations antenna diameter equal to 60 cm with some restriction on the power spectral density. According to the excess of interference, compatibility is verified for a VSAT antenna diameter of 60 cm with a maximum power spectral density greater than or equal to –53.5 dBW/Hz.

9.2.6.5 Analysis #4 of FSS (s- E) and Standard frequency and time signal-satellite (Earth to space) 9.2.6.5.1 Dynamic analysis The dynamic analysis was conducted to estimate the interference impact from FSS SS to SFTSSS. The following model was used in the dynamic analysis: FSS: – interfering FSS SS are located on GSO arc spaced by 3 degrees; – the maximum e.i.r.p. spectral density from one FSS SS to GSO is –20 dBW/Hz; – FSS SS use global beams with antenna pattern of 17º17º; – central transmission frequency 13.475 GHz. SFTSSS: – SFTSSS victim receiver is on ISS (orbit parameters: the height above the Earth’s surface is 430 km, orbit inclination 51.668 degrees); – central receiving frequency 13.475 GHz; – receiving antenna gain of SFTSSS SS is +6.5 dB in angle range of ±70º; – simulation period: 30 days, simulation step 30 s. The assessment of interference impact from FSS SS to SFTSSS SS is given below:

196 Rep. ITU-R S.2365-0 %

, e m i t

f o

e g a t n e c r e p

aggregate interference, dBW

As the graph shows the protection criterion for SFTSSS SS in the given time percentage (‒147 dB (W/MHz) for 0.1% of time) is not exceeded.

9.2.6.5.2 Static analysis The static analysis was conducted to estimate the protection distance between FSS ES and SFTSSS ES The maximum permissible aggregate interference level, the interference-to-noise ratio I/N= –12.2 dB (6%), where N- thermal noise of FSS ES, was used as the protection criterion for FSS ES (see Recommendation ITU-R S.1432). The permissible interference level at the FSS ES receiver input is determined by the following equation: P = P  (I / N) i n where:

Pi : power spectral density of interfering signal at FSS ES receiver input (dBW/MHz) 6 Pn = kT × (10 ): noise power spectral density of FSS ES receiver (dBW/MHz) I/N : permissible interference-to-noise ratio at FSS ES receiver input (dB) Т = 140К: typical equivalent noise temperature of FSS ES taken for calculations. Then the permissible power spectral density of interfering signal is:

Pi = –147.1 –12.2 = –159.3 dBW/MHz Based on the basic propagation losses described in the methodology given in Recommendation ITU-R P.452-14 the protection distance is defined. The estimation of the minimum required values of basic losses and the required protection distances was carried out under the following assumptions: FSS ES with antenna diameter of 0.6 m, 1.2 m, 2.4 m were considered. FSS ES are described in Recommendations ITU-R S.465-6 and ITU-R S.580-6, the minimum elevation angle of FSS ES receiving antenna is 10 degrees. The maximum power spectral density of SFTSSS ES is ‒19.5 dB(W/MHz),antenna gain is 32 dBi, feeder losses 1.5 dB, antenna pattern approximation is in accordance with Recommendation ITU-R S.465-6, the minimum elevation angle of SFTSSS ES antenna is 5 deg. Rep. ITU-R S.2365-0 197

SFTSSS SFTSSS Feeder SFTSSS FSS ES FSS ES Permissible Required Req. ES power ES losses, ES e.i.r.p. type antenna gain interference at propagation protection spectral antenna (dB) towards towards front end of losses , (dB) distance (km) density gain FSS ES SFTSSS ES FSS ES (dBW/М towards (dBW/М (dBi) receiver Hz) FSS ES Hz) (dBW/МHz) (dBi) 0.6 7 159.8 21 ‒159.3 –19.5 14.5 1.5 ‒6.5 1.2 4 156.8 19.5

2.4 4 156.8 19.5

As the Table shows the maximum separation distance for protection of FSS ES is 21 km. This value does not take into account the propagation path terrain of interfering signal and can be corrected taking into account diffraction and reflection due to natural obstacles.

9.2.6.5.3 Summary of FSS (s-E) and Standard frequency and time signal-satellite (Earth to space) Compatibility studies of the FSS (s-E) with the SFTSSS (E-s) showed the following: 1 The interference level from FSS SS to SFTSSS SS does not exceed the permissible level without using mitigation techniques. 2 The maximum separation distance for FSS ES protection is 21 km without taking into account the propagation path terrain of interfering signal. Based on the above it can be concluded that compatibility between FSS (s-E) and SFTSSS (E-s) exist.

9.2.6.6 Summary of FSS (E-s) and Standard frequency and time signal-satellite (Earth to space) With regard to sharing between Standard frequency and time signal-satellite (Earth to space) service and FSS (Earth-to-space), three studies have been performed to date. The first study using an outdated deployment model indicated that the protection criterion of –125 dBW/125 MHz was not exceeded, with a margin limited to 0.4 dB. The second study using the agreed upon deployment model based on the number of FSS transmissions indicated an interference level of exceeding the protection criterion by 7.6 dB. The third study using the agreed upon deployment model based on the allocation of the overall FSS frequency resource amongst diverse earth stations looked at differing FSS ES bandwidths and FSS ES power density values. The results indicated that a deployment of 60 cm FSS ES with power density levels of –50 dBW/Hz and –42 dBW/Hz showed harmful interference. However a FSS ES deployments of several bandwidths as well as FSS ES deployments using 60 cm antenna size with power densities of –55 dBW/Hz did not exceed the interference criteria. The last study indicated that the interference level from FSS SS to SFTSSS SS does not exceed the permissible level without using mitigation techniques with a maximum separation distance for FSS ES protection of 21 km without taking into account the propagation path terrain of interfering signal.

9.2.7 FSS (s-E) and FS and MS System parameters for FS point-to-point communication links allocated in the frequency bands between 7.1 and 14 GHz are given in Recommendation ITU-R F.758-5. The nominal value of maximum acceptable long-term interference power density at the FS station front end is –134+I/N dB(W/MHz). Taking into account protection criterion for long-term aggregate

198 Rep. ITU-R S.2365-0 interference I/N = –10 dB the maximum acceptable power density for long-term interference at the FS station front end will be –144 dB(W/MHz). Taking into account the maximum acceptable power density of –144 dB(W/MHz) for long-term aggregate interference at FS station, the mathematical description of FS station receiving antenna pattern given in Recommendation ITU-R F.1245 the pfd mask estimated for protection of FS station from one FSS satellite and several FSS satellites spaced by 3 degrees on GSO arc is shown below.

FIGURE 9-36 Summarized pfd mask for protection of FS stations from the potential FSS (s-E) allocation

-80

-85

-90

-95

-100

-105

-110 MHz

-115

in 1 in 2 -120

-125

-130 PFD, dBW/m PFD, -135 PFD level for FS station protection -140 GSO avoidance -145

-150 Aggregate PFD mask -155 PFD level according AI 1.6.1 -160 0 10 20 30 40 50 60 70 80 90 Arrival angles, deg.

The Figure shows that limitation of pfd would be between (–125 dB(W/m2·MHz)) and (–102 dB(W/m2·MHz)) for interfering signal arrival angles from 0º to 90º. Taking into account that there are no characteristics for MS in this frequency band the compatibility with MS will be achieved by using pfd mask developed for protection FS. Summary Compatibility conditions between FSS (space-to-Earth) and FS, MS stations are possible based on pfd limits into FSS space stations.

9.2.8 FSS (E-s) and FS and MS No sharing studies were submitted to the ITU-R for FSS (E-s) satellite systems and mobile systems in the band 13.4-13.75 GHz. No sharing studies were submitted to the ITU-R for FSS (E-s) satellite systems and fixed systems in the band 13.4-13.75 GHz.

9.2.9 FSS (E-s) and RNS As per RR No. 5.501, the band 13.4-13.75 GHz is also allocated on a primary basis to the radionavigation service in Azerbaijan, Hungary, Japan, Kyrgyzstan, Romania and Turkmenistan. Rep. ITU-R S.2365-0 199

In some of these countries, maritime RNS stations with characteristics similar to those listed in Recommendation ITU-R M.1644 are operated. Therefore, the RNS and the FSS can share the band 13.4-13.75 GHz at least in some of the countries listed above under the same conditions as those stipulated in RR Nos. 5.502, 9.17 and 9.18.

9.3 Summary of studies for the band 13.4-13.75 GHz 9.3.1 EESS (active) and FSS (space-to-Earth) See EESS (active) summary in § 8.3.

9.3.2 SFTSS (Earth-to-space) and FSS (space-to-Earth) The standard frequency and time signal-satellite (Earth to space) service limited compatibility based on the assumptions considered. Further studies are required to evaluate the impact of these assumptions.

9.3.3 FSS (E-s and s-E) and SRS See results of SRS / FSS sharing studies given in §§ 9.2.5.2.3 and 9.2.5.3.3.

10 Frequency band 14.5-14.8 GHz The allocations of this band in RR Article 5 are shown below.

TABLE 10-1 Excerpts from Article 5 of the Radio Regulations on allocation to services in 14.5-14.8 GHz

Allocation to services

Region 1 Region 2 Region 3 14.5-14.8 FIXED FIXED-SATELLITE (Earth-to-space) 5.510 MOBILE Space research 5.510 The use of the band 14.5-14.8 GHz by the fixed-satellite service (Earth-to-space) is limited to feeder links for the broadcasting-satellite service. This use is reserved for countries outside Europe.

10.1 Review of Recommendations A list of relevant Recommendations that may be useful for sharing studies is summarized in Table 10-2. The results are presented below:

200 Rep. ITU-R S.2365-0

TABLE 10-2 Summary of relevant Recommendations that may be useful for sharing studies in the band 14.5-14.8 GHz

Service Relevant Recommendation Fixed-satellite service Recommendation ITU-R S.1328 (Earth-to-space) Recommendation ITU-R S.1063 Fixed service Recommendation ITU-R F.758 Recommendation ITU-R F.636 Recommendation ITU-R F.699 Recommendation ITU-R F.1245 Recommendation ITU-R F.1336 Recommendation ITU-R F.1107 Recommendation ITU-R F.1333 Recommendation ITU-R F.1777 Mobile service Recommendation ITU-R M.2068 Space research service Recommendation ITU-R SA.609 Recommendation ITU-R SA.1019 Recommendation ITU-R SA.1155 Recommendation ITU-R SA.1018 Recommendation ITU-R SA.1414 Radio astronomy Recommendation ITU-R RA.769 (adjacent band) Recommendation ITU-R RA.1031-2 Recommendation ITU-R RA.1513-1

10.2 Sharing studies for the band 14.5-14.8 GHz Studies for sharing in this band must include (1) studies with other allocated services, and (2) studies within the FSS service, taking into account Resolution 152 (WRC-12).

10.2.1 FSS and BSS feeder links In examining the possibility for FSS Earth-to-space allocations in the 14.5-14.8 GHz band, the interference scenarios could be evaluated using Article 7 of Appendix 30A (AP 30A), which refers to the protection criteria of Annex 4 of AP 30A, and Article 6 of AP 30A. Resolution 151 (WRC-12) provides guidance on consideration of the 14.5-14.8 GHz band: 1) the band 14.5-14.8 GHz is part of the Regions 1 and 3 broadcasting-satellite service (BSS) feeder link Plan, contained in AP 30A, for 22 countries in Africa, Middle East and Asia Pacific.

Rep. ITU-R S.2365-0 201

TABLE 10-3 Characteristics of FSS Systems

R3 countries with assignments in the R1&3 feeder-link Plan in the 14.5-14.8 GHz frequency band Adm. Notice ID Satellite Name Orbital Position (deg.E) CHN 100550403 CHN19001 122 CHN 100550404 CHN19002 122 IND 100550443 INDA_101 55.8 IND 100550444 INDA_102 55.8 IRN 100550411 IRN10901 34 IRN 100550412 IRN10902 34 KOR 100550415 KOREASAT-1 116 KOR 100550416 KOREASAT-1 116 NPL 100550423 NPL12201 50 NPL 100550424 NPL12202 50 PAK 100550425 PAK12701 38.2 PAK 100550426 PAK12702 38.2 PNG 100550427 PNG13101 134 PNG 100550428 PNG13102 134 USA 100550439 USAC_101 140 USA 100550440 USAC_102 140

202 Rep. ITU-R S.2365-0

TABLE 10-4 Characteristics of FSS Systems

R1 countries with assignments in the R1&3 feeder-link Plan in the 14.5-14.8 GHz frequency band

Adm. Notice ID Satellite Name Orbital Position (deg.E) AFS 100550401 AFS02101 4.8 AFS 100550402 AFS02102 4.8 CME 100550405 CME30001 ‒13 CME 100550406 CME30002 ‒13 ETH 100550407 ETH09201 36 ETH 100550408 ETH09202 36 GHA 100550409 GHA10801 ‒25 GHA 100550410 GHA10802 ‒25 IRQ 100550413 IRQ25601 50 IRQ 100550414 IRQ25602 50 MOZ 100550417 MOZ30701 ‒1 MOZ 100550418 MOZ30702 ‒1 NIG 100550419 NIG11901 ‒19.2 NIG 100550420 NIG11902 ‒19.2 NMB 100550421 NMB02501 ‒18.8 NMB 100550422 NMB02502 ‒18.8 SDN 100550429 SDN__101 ‒7 SDN 100550430 SDN__102 ‒7 SEN 100550431 SEN22201 ‒37 SEN 100550432 SEN22202 ‒37 SEY 100550433 SEY00001 42.5 SEY 100550434 SEY00002 42.5 SOM 100550435 SOM31201 37.8 SOM 100550436 SOM31202 37.8 TGO 100550437 TGO22601 ‒30 TGO 100550438 TGO22602 ‒30 YEM 100550441 YEM__101 11 YEM 100550442 YEM__102 11 2) additions to the Region 1 and 3 List of BSS feeder link assignments can be made through the successful application of the Article 4 procedures of RR AP 30A; 3) Studies should include consideration of utilizing existing allocations to the FSS through a review of regulatory provisions except RR Nos. 5.502 and 5.503. 4) If consideration is given to the use of 14.5-14.8 GHz bands, appropriate measures need to be taken with regard to the AP 30A Plans and List to ensure the integrity and full protection of these bands, specifically taking into account as a minimum: Rep. ITU-R S.2365-0 203

a) required coordination procedures between AP 30A networks and any new fixed-satellite service utilization of the bands; b) the need for transmitting earth stations in the AP 30A Plans and List to be able to be located anywhere within their respective service areas; c) the need to appropriately protect assignments in the AP 30A Plan and List, as the case may be, from any new FSS utilization of the bands. Appropriate regulatory procedures together with calculation methods and modification to the Bureau software (for example, GIBC) need to be developed to implement any agreed criteria to protect assignments in the AP 30A Plan and List. In order to determine the appropriate criteria, interference simulation of the cumulative effect of the new FSS systems is needed to demonstrate that protection of the AP 30A Plan is ensured at levels equivalent to that of the EPM criteria in the Radio Regulations and together with the EPM reference situation of the Plan assignments and List. According to Recommendation ITU-R S.1063, studies have shown that coexistence of the FSS (Earth-to-space) and BSS feeder link assignments in the band 14.5-14.8 GHz is feasible. Since these studies were conducted 20 years ago, there have been some changes in AP 30A over this period and the sample characteristics used for studies should be reviewed. Start of quote from § 4.2 of Recommendation ITU-R S.1063: “Use of the 14.5-14.8 GHz frequency band WARC-ORB-88 adopted a Plan for BSS feeder links in the 14.5-14.8 GHz band for Region 1 and Region 3, which was later revised at WRC-2000. This Plan, which appears in RR AP 30A contains assignments to 19 countries in Africa and Asia, uses 17 orbital locations between 37° W and 128° E and divides the band into 14 channels spaced 19.18 MHz apart. The results of two studies into sharing between the FSS and BSS feeder links in this band are summarized in this section. These studies were carried out as part of the ex-CCIR preparation for WARC-92. Since that Conference decided that use of the band by the FSS should remain restricted to BSS feeder links, this section is included merely to illustrate the feasibility of 14/11 GHz band sharing. BSS feeder link transmission parameters were taken as those published in RR AP 30A. Two types of FSS carriers were assumed, FM-TV and digital (IDR – 64 kbit/s and 8 448 kbit/s). The interference analysis was based on the assumption of co-channel, co-coverage interference and no account was taken of polarization discrimination. The key results showed that: – an orbital separation of more than 2.5° is sufficient to protect the BSS feeder link assignments from the FSS under worst case co-coverage and co-frequency conditions; – for smaller orbital separations between FSS and BSS satellites, FSS TV could use the bands with constraints on the uplink earth station locations within the BSS coverage area; – the required orbital separations could be reduced if frequency separation is maintained between FSS TV and BSS assigned channel frequencies, and this appears to be possible; – the FSS carriers with higher bit rates can use the band 14.5-14.8 GHz in a way similar to FSS TV; – the sensitive carriers of the FSS can use the band by frequency planning the carriers around the BSS TV carriers and/or by avoiding certain contours of the BSS satellite antenna, depending on the orbital separation between the satellites. To summarize, the studies show that coexistence of the FSS and WARC ORB-88 BSS feeder link assignments in the band 14.5-14.8 GHz is feasible. The constraints on FSS networks using this band

204 Rep. ITU-R S.2365-0 are not onerous. For a new network to be positioned in most of the GSO, the constraints can be avoided altogether with appropriate choice of orbital location. For networks with limited orbital flexibility, the measures required are likely, in general, to be no greater in severity as compared to those experienced in normal coordination between FSS networks in current bands.” End of quote from § 4.2 of Recommendation ITU-R S.1063. 10.2.1.1 Review of regulatory procedures With respect to point number 4 in § 10.2.1 above regarding a review of regulatory procedures, AP 30A Plan has already established on the one hand limits for determining whether a service of an administration is considered to be affected by a proposed modification to either the Plans or List (Annex 1) and criteria for sharing between unplanned and planned satellite services (Annex 4). The table below provides a summary of the various criteria that have been established in these Annexes. Note – This Table is not meant to be exhaustive, but is rather meant to give a brief overview of the various mechanisms in place.

Annex & Coordination of With respect to Criteria applied Section A1, § 3 Modification to Region 2 feeder Current to Region 2 feeder link OEPM link Plan Plan and pending Article 4 degradation networks in Region 2 A1, § 4 Proposed new or modified Assignments in Region 1 and 3 1) pfd at GSO and assignment in Region 1 & 3 feeder feeder link Plan, List and pending off-axis e.i.r.p. link List Article 4 networks in Regions 2) Coordination 1&3 arc 3) EPM degradation A1, § 5 Modification to Region 2 feeder Assignment in Region 1 & 3 ∆T/T (6%) link Plan feeder link Plan, List and pending Article 4 networks in Regions 1&3 (17.3-18.1 GHz) Proposed new or modified Current to Region 2 feeder link ∆T/T (6%) assignment in Region 1 & 3 feeder Plan and pending Article 4 link List networks in Region 2 (17.3-17.8 GHz) A1, § 6 Proposed new or modified Current assignment in 17.8-18.1 ∆T/T (6%) assignment in Region 1 & 3 feeder GHz in Region 2 (FSS E-to-s) link List A4, § 1 Proposed assignment in 17.3-18.1 Receiving space station under ∆T/T (6%) GHz FSS allocation (space-to- Region 2 feeder link Plan or Earth) Region 1 and 3 Feeder link Plan (R1 &R3) or in 17.3-17.8 and List (unplanned) BSS allocation (R2) A4, § 2 Proposed assignment in 17.8-18.1 Receiving space station in Region ∆T/T (6%) GHz FSS allocation (Earth-to- 1 & 3 Feeder link Plan, List and space) (R2) pending Article 4 networks Two observations can be made in looking at these AP 30A coordination provisions. The first one is that FSS space stations and their associated transmitting earth stations operating in the 17.8-18.1 GHz band could very well be operating directly adjacent to BSS space stations receiving feeder-links in Rep. ITU-R S.2365-0 205 this band. In other words, FSS and BSS space stations can be operating in this band with relatively close proximity on the GSO arc. The second observation is that the limitations in orbital location (Annex 7 of Appendix 30) do not restrict the operation of a space station receiving in this entire band 17.3-18.1 GHz.

10.2.1.2 Technical feasibility of coordinating FSS systems with AP 30A Plan and List assignments in the 14.5-14.8 GHz band The technical feasibility for FSS systems to operate in the band 14.5-14.8 GHz, whilst maintaining the protection of the RR AP 30A planned assignments, has been assessed. The two studies below analysed the potential for coordinating new assignments in the 14.5-14.8 GHz band with the existing assignments in the Appendix 30A Plan and List. The results suggest that it is feasible for new FSS networks to be coordinated with Plan and List systems using the AP 30A procedures.

10.2.1.2.1 Study 1: Overview of the RR AP 30A Plan (14 GHz) The following observations can be made on AP30A Plan in the 14.5-14.8 GHz band: – it describes assignments to 22 receiving space stations, at 22 orbital locations; – it describes assignments only in Regions 1 and 3 (no assignments are made in Region 2); – the orbital location of the assignments are grouped in three broad groups: 37°W–11°E, 34°E-55.8°E and 116°E–140°E (see diagram below).

FIGURE 10-A Location of AP 30A Plan Assignments (14.5-14.8 GHz)

Location of Appendix 30A Plan Assignments in 14 GHz Band

10 20 30 40 50 60 70 80 90

-40 -30 -20 -10

100 110 120 130 140 Orbital Location (degrees East)

Article 4 of AP 30A describes the procedures to be followed by an administration wishing to propose new or modified assignments. These include seeking the agreement of any administrations potentially affected by the proposed assignment. Annex 1 to AP 30A describes the technical thresholds which should be applied in order to identify potentially affected administrations. Annex 3 to AP 30A describes the technical design parameters used to establish the Plan, including protection margins, rain attenuation margins and the respective earth station and space station antenna characteristics. This annex also indicates that the Plan did not consider interference contributions from systems located more than 9⁰ from the nominal location of an assignment. In addition to the Plan itself, a further 122 additional or modified networks3 have been filed in this band. Of these, 16 have completed the procedures of Article 4 and have been included in the AP 30A List.

3 As of BR IFIC No.2736 (January 22, 2013).

206 Rep. ITU-R S.2365-0

Simulation of new assignments in the 14.5-14.8 GHz range To assess the feasibility of adding new assignments in the 14.5-14.8 GHz range, compatible with existing Plan and List assignments in that range, a series of example systems were created and tested for compatibility using the AP 30A procedures and the BR MSPACEg software. These systems assumed a typical Earth-to-space FSS carrier from a 1.2 m antenna:

TABLE 10-5 Characteristics of FSS Systems

Parameters Assumed values Earth station diameter (m) 1.2 Earth station gain (dBi) 43.5 Carrier power (dBW) 18 Carrier bandwidth (MHz) 5.9 Carrier type Digital Modulation QPSK Carrier channels [polarisation] 1/3/5/7/9/11/13 [CR] 2/4/6/8/10/12/14 [CL]

Space station antenna gain (dBi) 32 Antenna major/minor axis 16° / 16° (degrees) Space station locations 40°W / 20°W / 0°E / 40°E / 60°E / 120°E / 140°E The example systems were created for seven orbital locations from 40°W to 140°E, and deployed a near-global beam pattern. In each case, the example system was located within 9 degrees or less of an assignment in the Plan to ensure that the MSPACEg software made the appropriate interference calculation. At least one test point was placed in the adjacent country to a Plan assignment, to maximise the likely impact on the Plan assignment. The example system was given a Date of Receipt of 19/12/2012, and the software set to examine all networks received prior to this date. A summary of the results is shown in the following table:

Rep. ITU-R S.2365-0 207

TABLE 10-6 Results from MSPACEg Software

Number of “Interfering Plan/List Affected networks ” network networks within ±9° Location Location Name Max. EPM degradation (dB) 40°W 6 40.5°W NSS-BSS 40.5W 8.05 20°W 13 20°W YAHSAT-BSS-20W 7.77 20°W DBL-G4-20W 8.49 0°E 15 (No affected (No affected network) - network) 20°E* 40°E 19 (No affected (No affected network) - network) 60°E 20 60°E YAHSAT-BSS2-60E 14.26 80°E* 100°E* 120°E 11 (No affected (No affected network) - network) 140°E 8 140°E USAC-101/102 0.58

(*Note: Orbital locations 20°E, 80°E and 100°E were not used in these simulations, as there are no Plan assignments within ±9°.) In order to further investigate the likely constraints on any new assignments, further compatibility analysis was made using a static method. Using the following assumptions, the carrier-to-interference (C/I) ratio was calculated for both an FSS carrier interfering into a Plan assignment and a Plan assignment interfering into an FSS carrier:

TABLE 10-7 Assumptions for Static Analysis

Plan Assignment FSS Carrier (typical) e.i.r.p. (dBW) 82 4 61.5 Bandwidth (MHz) 27 5.9 e.i.r.p. density (dBW/MHz) 67.7 53.8 Antenna size (m) 6 1.2 Off-axis pattern BO.1295 S.580 / BO.1213 C/I protection ratio (dB) 36 dB 5 20 dB

4 The Appendix 30A Plan specifies e.i.r.p. values in the range 82-89 dBW for assignments in the 14.5-14.8 GHz range. The lowest value (i.e. most vulnerable) was used.

5 Appendix 30A specifies an aggregate protection ratio of 30 dB for feeder links in the WRC-97 Plan; a further 6 dB was added to account for a single entry interferer.

208 Rep. ITU-R S.2365-0

In each case, it was assumed that both the Plan assignment and the FSS carrier operate in overlapping satellite beams (i.e. no satellite beam isolation). The isolation was calculated for satellite separations in the range 0⁰-5⁰, based on the differences in carrier power and on the earth station off-axis antenna patterns. The results of an FSS carrier (interferer) into a Plan assignment are as follows:

TABLE 10-8 Protection of Plan Assignment (static analysis)

Satellite separation Antenna isolation Total isolation (dB) (°) (dB) FSS -> Plan Isolation due to e.i.r.p. 0 0 –13.9 Additional antenna off- 1 –8.2 –22.1 axis isolation (BO.1213 / 2 –21.9 –35.8 S.580) 3 –26.3 –40.2 5 –31.9 –45.8 The Plan assumes a feeder link protection (C/I) criteria of 30 dB, for all sources of interference: co-channel, upper adjacent channel and lower adjacent channel. Allowing for a C/I of 36 dB (to account for a single-entry interferer), it can be seen that sufficient isolation can be achieved at only 2° satellite separation. The results of a Plan assignment (interferer) into an FSS carrier are as follows:

TABLE 10-9 Protection of FSS Carrier (static analysis)

Satellite separation Antenna isolation Total isolation (dB) (°) (dB) Plan -> FSS Isolation due to e.i.r.p. 0 0 +13.9 Additional antenna off- 1 –28 –14.1 axis isolation (BO.1295) 2 –35 –21.1 3 –40 –26.1 5 –45 –31.1 The protection criteria for VSAT FSS carriers is likely to be lower than for BSS feeder links – assuming a C/I value of 20 dB, sufficient isolation can be achieved at only 2⁰ separation. Analysis of results The AP 30A Plan contains 22 networks; a further 16 networks have been included in the associated List, and 109 networks have been filed but not yet reached agreement with affected administrations or brought into use. Initial analysis of the Plan for 14.5-14.8 GHz suggests that it would be feasible to coordinate additional FSS applications whilst protecting Plan assignments, due to the limited number of systems in that band. Detailed analysis using the MSPACEg software showed that the protection criteria for AP 30A Plan systems were exceeded only when the “victim” network was within 0.5° of the simulated “interfering” network. No Plan systems were affected when the test points fell outside of the service area of the assignment. In the case of the Plan assignment at 140°E, the test point lay within the service area, and the Rep. ITU-R S.2365-0 209

Equivalent Protection Margin (EPM) was degraded by 0.58 dB. Careful modification of the coverage area of the FSS system would likely reduce this EPM below the permitted threshold. In the case of List assignments – additional FSS systems that have been incorporated into the Plan - the MSPACEg results suggest that the impact is greater, with an EPM degradation of up to 14.3 dB. This suggests that List (FSS) systems are more sensitive but, in practice, the use of shaped beams would permit the coordination of new assignments with them. The static analyses usefully highlight the antenna isolation that can be achieved between Plan/List assignments and other FSS networks. Additional isolation may also be gained by careful design of the satellite beam(s). Summary This study analysed the potential for coordinating new assignments in the 14.5-14.8 GHz band with the existing assignments in the AP 30A Plan and List, using the MSPACEg software and also static methods. The results suggest that it is feasible for new FSS networks to be coordinated with Plan and List systems using the AP 30A procedures, with no changes to the existing procedures. A regulatory constraint exists in RR No. 5.510, however, limiting the band for use outside Europe and for feeder links to the BSS only. Use by other applications of the FSS would require a change to this footnote, or its deletion.

10.2.1.2.2 Study 2 Introduction The band 13.75-14.5 GHz is allocated to the fixed-satellite service (FSS) in the Earth-to-space direction. Further spectrum is sought to balance the downlink allocations in Regions 2 and 3, and also to enhance capacity in Region 1. The adjacent band 14.5-14.8 GHz is allocated to the FSS (Earth-to-space) on a worldwide basis, but is subject to footnote RR No. 5.510. This footnote currently limits its use to feeder links for the broadcasting-satellite service (BSS). The band is subject to the AP 30A Plan, for feeder links to the BSS. Study 1 examined the technical feasibility for other FSS systems to operate in the band 14.5-14.8 GHz, and concluded that it would be technically feasible to coordinate additional FSS applications whilst fully protecting Plan assignments, due to the limited number of systems in that band. Study 2 verifies the results of Study 1 and tests its main conclusion that with careful planning multiple FSS systems can coexist with the AP 30A planned assignments. In this study the MSPACEg analysis of the earlier study is extended to test the conclusion that with minor adjustments to orbital location of the FSS system the EPM degradation is reduced to acceptable levels. It further investigates the effect of multiple FSS systems on the protection ratio to assess the impact of multiple systems on the Plan assignments. Overview of the AP 30A Plan (14 GHz) The Plan contained in AP 30A addresses the 14.5-14.8 GHz band and the 17.3-18.1 GHz band. In the 14.5–14.8 GHz band, the AP 30A plan describes assignments to only 22 receiving space stations, at 22 orbital locations, all located within Regions 1 and 3 (no assignments are made in Region 2).

210 Rep. ITU-R S.2365-0

In addition to the Plan itself, it has been reported that a further 122 additional or modified networks6 have been filed in this band. Of these, 16 have completed the procedures of Article 4 and have been included in the AP 30A List. Feasibility of introducing unplanned FSS assignments in the 14.5-14.8 GHz band Study 1 assessed the feasibility of adding new assignments in the 14.5-14.8 GHz range using two methods. A series of example FSS test systems were created and tested for compatibility using the AP 30A procedures and the BR MSPACEg software. The study assessed the effect of introducing seven example systems at orbital locations from 40°W to 140°E. At least one test point was placed in the adjacent country to a Plan assignment to maximise the likely impact on the Plan assignment (see Study 1 for list of test points). Only one result showed degradation in the Equivalent Protection Margin (EPM) for a Plan assignment greater than the permitted threshold (USAC-101/102 at 140°E). In this case the satellites were collocated and the test point was within the service area for the Plan assignment, resulting in an EPM degradation of 0.58 dB. Careful modification of the coverage area of the FSS system would likely reduce this EPM degradation below the permitted threshold. By comparison the Plan assignment at 19.2°W (NIG11902) did not experience degradation in the EPM beyond the permitted threshold with an example system at 20°W, and a test point in a country adjacent to the service area. These results suggest that with small orbital offsets, the Plan assignments are not affected by other FSS systems. The second method, a static analysis, also showed that in the case where a Plan assignment is potentially affected, small changes to the orbital location and/or coverage area could ensure that such assignments are unaffected. These results indicate that coordination is feasible for new FSS systems in the band, while protecting assignments in the Plan. Simulation of new assignments in the 14.5-14.8 GHz range Study 1 assessed the feasibility of adding new assignments in the 14.5-14.8 GHz rang by creating a series of example systems as noted above. Four of the test systems caused an EPM degradation greater than 0.45 dB. Of the affected systems only one belonged to the Plan, the remainder were List systems. The Plan assignment at 140°E was only affected because the test point lay within the service area and the satellites were collocated. The affected List systems were either co-located or within 0.5° of the FSS system. To confirm the conclusion of Study 1 that modification of the FSS system would reduce the EPM degradation below the permitted threshold, the analysis using MSPACEg was repeated using the same FSS system characteristics but with minor adjustments to the orbital location compared to the original test systems. The tests were only done for those systems that experienced EPM degradation results presented in the Table 10-10, alongside the corresponding results from Study 1.

6 As of BR IFIC No. 2736 (January 22, 2013). Rep. ITU-R S.2365-0 211

TABLE 10-10 Results from MSPACEg Software

Interfering Interfering Affected Networks (as Affected Networks (as per 4A/234-E) Network Network per this contribution)* Max EPM New Max EPM Degradation Location Location Name Degradation Location (dB) (dB) 40°W 40.5°W NSS-BSS 40.5W 8.05 38.5°W - YAHSAT-BSS- 20°W 7.77 - 20W 20°W 22°W

20°W 8.49 - DBL-G4-20W 60°E 60°E YAHSAT-BSS2- 14.26 58°E - 60E 140°E 140°E USAC-101/102 0.58 138°E - * A ‘-‘ indicates that no EPM degradation was reported by MSPACEg as a result of the test network.

The results presented in the Table above show that the EPM degradation for each of the previously affected networks, was reduced to within acceptable limits by adjusting the orbital location of the FSS test system. In the case of the Plan assignment at USAC-101/102, inspection of the previous test results confirmed that the EPM degradation shown in the original analysis was the result of a single test point within the service area of the satellite. By elimination of this test result from the analysis, the EPM degradation is reduced to within acceptable limits. This implies that through careful design of the coverage area and selection of Orbital location new FSS networks can be coordinated with Plan and List systems. Static Analysis with multiple systems Study 1 carried out a Static Analysis to calculate carrier-to-interference (C/I) for a single FSS carrier interfering into a plan assignment. In this contribution the analysis has been extended to multiple FSS carriers. Using the same FSS characteristics as Study 1 test systems were established at ±2º, ±4º and ±6º from a theoretic plan assignment and the aggregate C/I as a result of the six systems calculated. For the static analysis it was assumed that both the Plan assignment and the FSS carrier operate in overlapping satellite beams (i.e. no satellite beam isolation). Using the following assumptions, the carrier-to-interference (C/I) ratio was calculated for both an FSS carrier interfering into a Plan assignment:

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TABLE 10-11 Assumptions for Static Analysis

Plan Assignment FSS Carrier (typical) e.i.r.p. (dBW) 82 7 61.5 Bandwidth (MHz) 27 5.9 e.i.r.p. density 67.7 53.8 (dBW/MHz) Antenna size (m) 6 1.2 Off-axis pattern BO.1295 S.580 / BO.1213 Range (km) 41,679 35,786 FSL at 14.5GHz (dB) 208.1 206.7 The calculation assumes worst case conditions: − FSS uplink antennas are located in the service area of the BSS system − The range from the FSS systems to the BSS satellite is at the minimum possible range resulting in the minimum path loss − The BSS system is transmitting at 82 dBW8 and has the maximum range resulting in the maximum path loss. The results are presented below:

TABLE 10-12 Protection of Plan Assignment (static analysis) with Multiple FSS systems

FSS e.i.r.p. e.i.r.p. density e.i.r.p. density Boresight Antenna Pointing System FSL toward Plan toward plan at Plan system e.i.r.p. Diameter isolation Offset (dB) system system satellite (dBW) (m) (dB) (deg) (dBW) (dBW/MHz) (dBW/MHz) –6 1.2 33.8 27.7 20.0 –186.8 –4 1.2 29.4 32.1 24.4 –182.3 –2 1.2 21.9 39.6 31.9 –174.8 61.5 206.7 2 1.2 21.9 39.6 31.9 –174.8 4 1.2 29.4 32.1 24.4 –182.3 6 1.2 33.8 27.7 20.0 –186.8 Aggregate –170.9 Plan System N/A 82.0 208.1 6.0 – 82.0 67.7 –140.4 Carrier-to-Interference (dB) 30.5

7 The Appendix 30A Plan specifies e.i.r.p. values in the range 82-89 dBW for assignments in the 14.5-14.8 GHz range. The lowest value (i.e. most vulnerable) was used. 8 The Appendix 30A Plan specifies e.i.r.p. values in the range 82-89 dBW for assignments in the 14.5-14.8 GHz range. The lowest value (i.e. most vulnerable) was used. Rep. ITU-R S.2365-0 213

AP 30A specifies an aggregate protection ratio of 30 dB for feeder links in the WRC-97 Plan. This analysis indicates that this aggregate protection ratio can be achieved in the presence of multiple FSS systems. Conclusions This study has confirmed that it is technically feasible to add new assignments to the 14.5-14.8 GHz band while protecting the AP 30A Plan and List assignments. It has reviewed and extended the analysis undertaken in Study 1 by looking at the effect of modification to the FSS systems to achieve acceptable EPM degradation and the impact of aggregate interference into a Plan assignment from multiple FSS systems. Analysis with MSPACEg software demonstrated that by small adjustments to the orbital location of the FSS test system, EPM degradation could be maintained within acceptable limits. Inspection of earlier results also indicated that by careful design of the coverage area of the FSS system, EPM degradation could be maintained within acceptable limits. Static analysis using worst case assumptions demonstrated that the aggregate protection ratio of 30 dB for feeder links in the WRC-97 Plan could still be satisfied with multiple FSS systems. This analysis assumed that the FSS earth station was in the coverage area of the Plan assignment and that the only protection was due to the isolation provided by the FSS earth station antenna pattern. Greater protection would be achieved if the FSS earth station is located outside the coverage area. The application of standard technics will enable the operation of multiple new FSS systems without causing unacceptable interference to Plan assignments.

10.2.1.2.3 Study #3 Cumulative Interference from FSS Networks To ensure the protection of the Appendix 30A Plan and List a study of the cumulative interference from several adjacent FSS networks was assessed. FSS networks were placed at varying intervals within 9 degrees of the Nigerian Plan assignment at 19.2°W to determine the individual and aggregate impact to the plan assignment. Several FSS network spacing environments were considered: 2-degree spacing, 0.5-degree spacing, and a combination of 2-degree and 0.5-degree spacing. Assumptions The parameters for the Nigerian assignment are those taken from Appendix 30A and summarized in Table 10-13 below. The satellite receive gain, transmit earth station gain, transmit earth station e.i.r.p., carrier bandwidth, and protection ratio for the assignment are given in Table 3A1 of Article 9A. The satellite receive noise temperature and the required C/N for the Nigerian assignment were taken from Annex 3. All calculations assume that the earth station transmitting to the Nigerian assignment is located on the-3dB satellite beam contour. The carrier analyzed from this station was transmitted at 14.65 GHz.

214 Rep. ITU-R S.2365-0

TABLE 10-13 Nigerian Assignment Parameters BSS assignment NIG11901 Location (°) –19.2 E Satellite Receive Gain (dBi) 38.05 Satellite Relative Gain Contour (dB) –3 Satellite Receive Noise Temp (K) 750 Transmit Earth Station Diameter (m) 6 Transmit Earth Station Gain (dBi) 57.0 Transmit Earth Station E.I.R.P. (dBW) 82.0 Transmit Earth Station E.I.R.P. Density (dBW/Hz) 7.69 Carrier Bandwidth (MHz) 27 Carrier Center Frequency (GHz) 14.65 C/N (dB) 34.3 Required C/N (dB) 24 Margin (dB) 10.3 pfd (dBW/m2) –94.4 Protection Ratio (dB) 27

The parameters assumed for the FSS networks are summarized in Table 10-14. The earth station transmitting to the FSS system is assumed to be 1.2 m with an on-axis gain of 43.4 dBW. The off- axis gain pattern is taken from Recommendation ITU-R BO.1213 for angles less than or equal to 1.5°. For angles larger than 1.5° 29-25 log(θ) was uses as the off-axis gain pattern. These patterns were used because the off-axis patterns given in AP 30A are in reference to a 6-m antenna. The patterns used in the study were selected to model a wider main beam and larger off-axis gain, that is typical of VSAT antennas, than the patterns in AP 30A. The input power density into the antenna is assumed to be −50 dBW/Hz. This value is greater than or equal to the power currently transmitted by ~95% of VSATs as shown in Fig. 2 of Report ITU-R S.2364. The input power density into the antenna is assumed to be ‒50 dBW/Hz. The carrier bandwidth and center frequency are the same as those used for the carrier transmitted to the Nigerian Assignment.

TABLE 10-14 FSS Network Parameters Transmit Earth Station Diameter (m) 1.2 Transmit Earth Station Gain (dBi) 43.4 Transmit Earth Station Off-Axis Gain BO.1213 Input Power Density (dBW/Hz) –50 Carrier Bandwidth (MHz) 27 Carrier Center Frequency (GHz) 14.65

2-Degree Spacing Scenario In this scenario, FSS networks were placed at 2 degree intervals up to 8 degrees away from the Nigerian Plan assignment at 19.2°W. There were 8 FSS networks considered (11.2°W, 13.2°W, Rep. ITU-R S.2365-0 215

15.2°W,17.2°W, 21.2°W, 23.2°W, 25.2°W and 27.2°W). The coverage of the FSS networks overlapped the coverage of the plan assignment. The earth stations transmitting to the FSS networks were placed at the center of the of the Nigerian assignment satellite beam. This is done to simulate the worst case environment where the interference from the earth stations transmitting to the adjacent satellites has the largest impact to the carrier transmitted to the Nigerian assignment. The single-entry and aggregate co-channel C/I, C/(N+I) and pfd values were calculated. The calculations were done only for one polarization and do not include adjacent channels. The reference bandwidth for the pfd calculations is 1 MHz. The aggregate co-channel values were calculated for each new FSS network that was added after the first. The first calculation is based on the addition of two FSS networks. Then, the next aggregate value is based on three FSS networks and this continues up to a total of eight networks. It is assumed the networks closest to the Nigerian assignment are added first. The order that the FSS networks were added for the aggregate analyses is given in Table 10-15. Figures 10-1 to 10-6 show the results of the calculations.

TABLE 10-15 Order of FSS Networks for 2-Degree Scenario

Network Location FSS1 21.2°W FSS2 17.2°W FSS3 23.2°W FSS4 15.2°W FSS5 25.2°W FSS6 13.2°W FSS7 27.2°W FSS8 11.2°W

FIGURE 10-1 Single-Entry C/I, 2-Degree Spacing Scenario Single-Entry C/I 51.0 49.0 47.0 45.0 43.0

dB 41.0 39.0 37.0 35.0 33.0 -29.2 -24.2 -19.2 -14.2 -9.2 Orbital Location

216 Rep. ITU-R S.2365-0

FIGURE 10-2 Aggregate C/I, 2-Degree Spacing Scenario Aggregate C/I 31.4 31.2 31.0 30.8

dB 30.6 30.4 30.2 30.0 1 2 3 4 5 6 7 8 9 Number of FSS Systems

FIGURE 10-3 Single-Entry C/(N + I), 2-Degree Spacing Scenario Single-Entry C/(N+I) 34.5 34.0 33.5 33.0

dB 32.5 32.0 31.5 31.0 -29.2 -24.2 -19.2 -14.2 -9.2 Orbital Location

Rep. ITU-R S.2365-0 217

FIGURE 10-4 Aggregate C/(N + I), 2-Degree Spacing Scenario Aggregate C/(N+I) 29.6 29.5 29.4 29.3 29.2 dB 29.1 29.0 28.9 28.8 28.7 1 2 3 4 5 6 7 8 9 Number of FSS Systems

FIGURE 10-5 Single-Entry pfd, 2-Degree Spacing Scenario Single-Entry pfd -130.0 -132.0 -134.0 -136.0 -138.0

-140.0 dBW/m2 -142.0 -144.0 -146.0 -148.0 -29.2 -24.2 -19.2 -14.2 -9.2 Orbital Location

218 Rep. ITU-R S.2365-0

FIGURE 10-6 Aggregate pfd, 2-Degree Spacing Scenario Aggregate pfd -129.5

-130.0

-130.5

dBW/m2 -131.0

-131.5

-132.0 1 3 5 7 9 Number of FSS Systems

0.5-Degree Spacing Scenario This scenario places FSS networks with beams that are geographically isolated from the plan assignment at 0.5 degree intervals up to 9 degrees. The 0.5 degree scenario is used to show a worst- case interference environment and would not represent the practical distribution of FSS networks. There were 36 FSS networks considered. To simulate the geographic isolation of the FSS network beams, the earth stations transmitting to the FSS networks were placed at the –20 dB contour of the of the Nigerian assignment satellite beam. The single-entry and aggregate C/I, C/(N+I) and pfd values were calculated. The reference bandwidth for the pfd calculations is 1 MHz. The aggregate values were calculated for each new FSS network that was added after the first. The first calculation is based on the addition of two FSS networks. Then, the next aggregate value is based on three FSS networks and this continues up to a total of 36 networks. It is assumed the networks closest to the Nigerian assignment are added first. The order that the FSS networks were added for the aggregate analyses is given in Table 10-16. Figures 10-7 to 10-12 show the results of the calculations.

TABLE 10-16 Order of FSS Networks for 2-Degree Scenario

Network Location Network Location Network Location Network Location FSS1 19.7°W FSS10 16.7°W FSS19 24.2°W FSS28 12.2°W FSS2 18.7°W FSS11 22.2°W FSS20 14.2°W FSS29 26.7°W FSS3 20.2°W FSS12 16.2°W FSS21 24.7°W FSS30 11.7°W FSS4 18.2°W FSS13 22.7°W FSS22 13.7°W FSS31 27.2°W FSS5 20.7°W FSS14 15.7°W FSS23 25.2°W FSS32 11.2°W FSS6 17.7°W FSS15 23.2°W FSS24 13.2°W FSS33 27.7°W FSS7 21.2°W FSS16 15.2°W FSS25 25.7°W FSS34 10.7°W FSS8 17.2°W FSS17 23.7°W FSS26 12.7°W FSS35 28.2°W FSS9 21.7°W FSS18 14.7°W FSS27 26.2°W FSS36 10.2°W Rep. ITU-R S.2365-0 219

FIGURE 10-7 Single-Entry C/I, 0.5-Degree Spacing Scenario Single-Entry C/I 75.0 70.0 65.0 60.0 55.0 dB 50.0 45.0 40.0 35.0 30.0 -29.2 -24.2 -19.2 -14.2 -9.2 Orbital Location

FIGURE 10-8 Aggregate C/I, 0.5-Degree Spacing Scenario Aggregate C/I 30.9 30.8 30.7 30.6 30.5

30.4 dB 30.3 30.2 30.1 30.0 29.9 1 6 11 16 21 26 31 36 Number of FSS Systems

220 Rep. ITU-R S.2365-0

FIGURE 10-9 Single-Entry C/(N + I), 0.5-Degree Spacing Scenario Single-Entry C/(N+I) 35.0 34.5 34.0 33.5 33.0

32.5 dB 32.0 31.5 31.0 30.5 30.0 -29.2 -24.2 -19.2 -14.2 -9.2 Orbital Location

FIGURE 10-10 Aggregate C/(N + I), 0.5-Degree Spacing Scenario Aggregate C/(N+I) 29.3

29.2

29.1

29.0 dB 28.9

28.8

28.7

28.6 1 6 11 16 21 26 31 36 Number of FSS Systems

Rep. ITU-R S.2365-0 221

FIGURE 10-11 Single-Entry pfd, 0.5-Degree Spacing Scenario Single-Entry pfd -110 -115 -120 -125 -130

dB/m2 -135 -140 -145 -150 -29.2 -24.2 -19.2 -14.2 -9.2 Orbital Location

FIGURE 10-12 Aggregate pfd, 0.5-Degree Spacing Scenario Aggregate pfd -107.3 -107.4 -107.5 -107.6 -107.7 -107.8

-107.9 dBW/m2 -108 -108.1 -108.2 -108.3 1 6 11 16 21 26 31 36 Number of FSS Systems

Combination of 2-Degree and 0.5-Degree Spacing This scenario places FSS networks with overlapping coverage with the plan assignment at 2 degree intervals and FSS networks with beams that are geographically isolated from the plan assignment at 0.5 degree intervals between the 2-degree overlapping coverage FSS networks. The combination of the two previous scenarios serves to simulate a worst-case operational environment. There were 36 FSS networks considered. The earth stations transmitting to the FSS networks spaced at 2 degrees were placed at the center of the of the Nigerian assignment satellite beam. To simulate the geographic isolation of the 0.5 degree spaced FSS network beams, the earth stations transmitting to the FSS networks were placed at the –20 dB contour of the of the Nigerian assignment satellite beam. The single-entry and aggregate C/I, C/(N+I) and pfd values were calculated. The

222 Rep. ITU-R S.2365-0 reference bandwidth for the pfd calculations is 1 MHz. The aggregate values were calculated for each new FSS network that was added after the first. The first calculation is based on the addition of two FSS networks. Then, the next aggregate value is based on three FSS networks and this continues up to a total of 36 networks. It is assumed the networks closest to the Nigerian assignment are added first. The order and beam coverage of the FSS networks used for the aggregate analyses is given in Table 10-17. Figures 10-13 to 10-16 show the results of the calculations.

TABLE 10-17 Order of FSS Networks for 2-Degree Scenario

Network Location Coverage Network Location Coverage FSS1 19.7°W Geog. Isolated FSS19 24.2°W Geog. Isolated FSS2 18.7°W Geog. Isolated FSS20 14.2°W Geog. Isolated FSS3 20.2°W Geog. Isolated FSS21 24.7°W Geog. Isolated FSS4 18.2°W Geog. Isolated FSS22 13.7°W Geog. Isolated FSS5 20.7°W Geog. Isolated FSS23 25.2°W Co-Coverage FSS6 17.7°W Geog. Isolated FSS24 13.2°W Co-Coverage FSS7 21.2°W Co-Coverage FSS25 25.7°W Geog. Isolated FSS8 17.2°W Co-Coverage FSS26 12.7°W Geog. Isolated FSS9 21.7°W Geog. Isolated FSS27 26.2°W Geog. Isolated FSS10 16.7°W Geog. Isolated FSS28 12.2°W Geog. Isolated FSS11 22.2°W Geog. Isolated FSS29 26.7°W Geog. Isolated FSS12 16.2°W Geog. Isolated FSS30 11.7°W Geog. Isolated FSS13 22.7°W Geog. Isolated FSS31 27.2°W Co-Coverage FSS14 15.7°W Geog. Isolated FSS32 11.2°W Co-Coverage FSS15 23.2°W Co-Coverage FSS33 27.7°W Geog. Isolated FSS16 15.2°W Co-Coverage FSS34 10.7°W Geog. Isolated FSS17 23.7°W Geog. Isolated FSS35 28.2°W Geog. Isolated FSS18 14.7°W Geog. Isolated FSS36 10.2°W Geog. Isolated

Rep. ITU-R S.2365-0 223

FIGURE 10-13 Single-Entry C/I, 0.5/2-Degree Spacing Scenario Single Entry C/I 75.0 70.0 65.0 60.0 55.0 dB 50.0 45.0 40.0 35.0 30.0 -29.2 -24.2 -19.2 -14.2 -9.2 Orbital Location

FIGURE 10-14 Aggregate C/I, 0.5/2-Degree Spacing Scenario

224 Rep. ITU-R S.2365-0

FIGURE 10-15 Single-Entry C/(N+I), 0.5/2-Degree Spacing Scenario Single Entry C/(N+I) 35.0 34.5 34.0 33.5 33.0

32.5 dB 32.0 31.5 31.0 30.5 30.0 -29.2 -24.2 -19.2 -14.2 -9.2 Orbital Location

FIGURE 10-16 Aggregate C/(N+I), 0.5/2-Degree Spacing Scenario

Rep. ITU-R S.2365-0 225

FIGURE 10-17 Single-Entry pfd, 0.5/2-Degree Spacing Scenario Single-Entry pfd -110 -115 -120 -125 -130

dB/m2 -135 -140 -145 -150 -29.2 -24.2 -19.2 -14.2 -9.2 Orbital Location

FIGURE 10-18 Aggregate pfd, 0.5/2-Degree Spacing Scenario Aggregate PFD -107.3 -107.4 -107.5 -107.6 -107.7 -107.8

-107.9 dBW/m2 -108 -108.1 -108.2 -108.3 1 6 11 16 21 26 31 36 Number of FSS Systems

Conclusion The analyses were conducted to simulate an aggregate interference environment. The worst-case environment studied in Scenario 3 combined co-coverage, co-frequency FSS systems every 2 degrees up to 8 degrees with non co-coverage, co-frequency FSS systems in between at 0.5 degree intervals up to 9 degrees. The analyses showed that in all scenarios, when FSS systems were added within the coordination arc of a Plan assignment using an input power spectral density of –50 dBW/Hz, the aggregate co-channel C/(N+I) for the carrier received by a satellite at the Nigerian assignment was higher than the minimum C/N required for the Nigerian assignment in Appendix 30A. Also, the aggregate co-channel C/I, calculated using a single polarization, was higher than the protection ratio defined for the Nigerian assignment in AP 30A. It is noted that the pfd calculations for the 0.5-degree and 0.5/2-degree spacing combination scenarios, scenarios 2 and 3 respectively, gave the same results since the earth station

226 Rep. ITU-R S.2365-0 location in the Nigerian assignment beam is not considered. Any trigger used to signal coordination will need to take the difference in interference seen at the Plan assignment due to beam isolation into account.

10.2.1.2.4 Study #4 Cumulative effect of multiple FSS assignments on AP30A Plan assignments Introduction This study presents a possible sharing scenario between FSS systems and BSS feeder link assignments of the RR Appendix 30A Plan and List in the 14.5-14.8 GHz band. In addition, the document proposes a method for examination of a new FSS system, which maintains a similar level of protection for existing BSS feeder link assignments in RR Appendix 30A Plan or List, without over-burdening the BR. Methodology In this study we examine the cumulative effect of multiple FSS systems on an existing RR Appendix 30A BSS feeder-link assignment, where the new FSS uplink system has an orbital separation of at least 20 from the BSS feeder link assignment. Description Three Appendix 30A Plan assignments (hereinafter "BSS feeder-links") were selected for examination, each having a different reference EPM value: AFS at 4.8°E NIG at 19.2°W IND at 55.8°E NOTE ‒ Table 10-19, presents the lowest and the highest EPM reference values for all Appendix 30A Plan assignments in Regions 1 and 3 (updated to BR IFIC 2769) for reference. For each of the BSS feeder-links above, 16 new potential FSS systems were added inside the 9 degrees arc on both sides of the BSS feeder-link. On each side, the first potential FSS system was placed at 2° of orbital separation from the BSS feeder-link, and the rest were placed 1° from each other. For example, inside the 90 arc on both sides of the AFS Plan assignment at 4.8°E, 8 new FSS systems were placed at: 6.8°E, 7.8°E, … , 15.8°E and 8 new FSS systems were placed at 2.8°E, 1.8°E, … , 4.2°W. All new FSS systems have a global service area and a test point at the boresight of each of the BSS feeder-links mentioned above. The parameters for all new FSS systems were identical. The 16 new FSS systems in the ±9 degrees arc from the BSS feeder-link represent a highly unlikely worst-case interference scenario for the BSS feeder-link, as at least 2 degrees of orbital separation are usually required for the FSS systems. MSPACE simulation is performed to calculate the cumulative effect of all 16 new FSS systems on the EPM situation of each of the above mentioned BSS feeder-links. The analysis was performed using data from ITU-R BRIFIC 2769. Parameters of the new FSS systems Antenna pattern: APELUX201V01 – this AP30A pattern is similar to the antenna pattern described in Recommendation ITU-R S.580-6, which is widely used for FSS submissions in the non-planned bands. Rep. ITU-R S.2365-0 227

Earth station antenna size: The antenna size is set at 0.75 m. At 2° orbital separation the off axis antenna gain is 29-25*log(phi), where phi is the topocentric angle. According to the antenna pattern in Recommendation ITU-R S.580-6, any antenna size larger than 0.75 cm has the same off-axis mask. Therefore, the off-axis E.I.R.P. of the new FSS systems is set by the power density they employ. Power Density: Two different power density levels are examined: ‒51 and ‒54 (dBW/Hz). The EPM criterion used in RR Appendix 30A For c and i in power terms, EPM is calculated using the following equation: EPM =10 log (c/iagg)– Protection Margin (dB). For Appendix 30A Plan Assignments the Protection Margin is 30 (dB).

10 log (c/iagg) =10log c / (i1+i2+…+in) – the aggregate C/I value (dB) with all interfering signals taken into account. The EPM degradation is essentially a C/I degradation. An existing assignment is considered to be affected by a new assignment if its EPM reference value is degraded below the level of –0.45 (dB). For example, if an assignment has a positive EPM reference value of 10 (dB), it is considered as affected by a new assignment only if its EPM reference value is degraded by more than 10.45 (dB). Results The results in Table 10-18 below show in which cases the BSS feeder-links are affected by the 16 new FSS systems according to the EPM criterion.

TABLE 10-18 Effect of new FSS systems on BSS feeder-links based on the EPM criterion

BSS New FSS BSS Feeder-Link BSS Feeder-Link EPM Feeder- Systems Power EPM Reference EPM Reference affected? Link Density Value without the Value with the FSS (dBW/Hz) FSS systems (dB) systems (dB) NIG –51 4.158 –1.012 Yes –54 4.158 0.84 No AFS –51 –39.557 –39.559 No IND –51 24.411 2.046 No

• The BSS feeder-link EPM reference value with the FSS systems is obtained from the results of MSPACE simulation • The BSS Feeder-link EPM reference value without the FSS systems is obtained from BRIFIC 2769 Appendix 30A database Results Analysis The results summarized in Table 10-18 above show that the aggregate effect of the 16 new FSS systems in the ±9° arc on the an existing BSS feeder-link using the EPM criterion is dependent on the EPM reference value of the BSS feeder-link. In cases where the BSS feeder-link EPM reference value without the FSS systems is either low or high, the cumulative effect of the 16 additional FSS systems do not trigger the EPM criterion.

228 Rep. ITU-R S.2365-0

In addition, for the BSS feeder-link having EPM reference value close to 0 dB, the 16 new FSS systems create a low amount of interference even when a very high power density of ‒51 dBW/Hz is used. This BSS feeder-link is not affected when the new FSS systems are limited to a power density of ‒54 dBW/Hz. This study shows that by limiting the power density emanated from the new FSS systems to −54 dBW/Hz, the BSS feeder-links separated by more than 2 degrees from the new FSS systems are not affected even in a highly unlikely scenario of 16 new FSS systems in the ±9 degrees arc. Conclusions The study has examined the cumulative effect of multiple FSS systems on an existing RR Appendix 30A BSS feeder-link assignment, where the new FSS uplink system has an orbital separation of at least 2 degrees from the BSS feeder link assignment. Based on the results above, the following pfd hard-limit mask may be an efficient way to examine new FSS systems with respect to the existing BSS feeder-links in the 14.5-14.8 GHz band, while ensuring the full protection of the RR Appendix 30A Plan in this band, and without over-burdening the BR: 2 pfd = –187.1 – 25*log10(orbital separation) dB(W/(m · Hz)) where: * 2 pfd = PD Limit (dBW/Hz) + 29 – 25*log10(orbital separation) – FPL dB(1/m ) *FPL – Free path loss, 4πr2 NOTE ‒ Based on later, more precise calculations, the PD value upon which this pfd mask is based on was updated to –52 dBW/Hz. Thus the pfd value proposed is: 2 pfd = ‒185.1 – 25*log10(orbital separation) dB(W/(m · Hz)) The pfd mask is based on an FSS earth station using 0.75 m antenna (or greater), the Recommendation ITU-R S.580-6 antenna pattern, and a power density of ‒54 dBW/Hz. The pfd mask is limited to an orbital separation of 2 degrees to 9 degrees between the FSS and the BSS feeder-link respective receiving space station. Figure 10-19 shows the pfd mask in orbital separations of between 2 degrees and 9 degrees. Rep. ITU-R S.2365-0 229

FIGURE 10-19

Off-Axis PFD Mask For an FSS Network in the 14.5-14.8 GHz Band -194 Hard Limit -196

-198

*Hz] -200

-202

-204

-206

Off Axis PFD [dBW/m -208

-210

-212 0 1 2 3 4 5 6 7 8 9 Orbital Separation [deg]

Finally, a previous study presented in § 10.2.1.3.1.1 has examined the single entry effect of a new FSS system on an existing BSS feeder-link, when both are co-located, and having co-frequency and co-coverage. The study was also done using MSPACE simulation. The single entry pfd value concluded at § 10.2.1.3.1.1 could be used as a basis for triggering coordination between a new FSS system and existing BSS feeder-link when the FSS system is located less than 2° from the existing BSS feeder-link.

TABLE 10-19 Plan assignments of Appendix 30A in Regions 1 and 3 – Lowest and highest EPM reference values

Low ID ADM Name Longitude High EPM EPM 100550401 AFS AFS02101 4.8 –39.557 –31.513 100550402 AFS AFS02102 4.8 –39.557 –30.423 100550404 CHN CHN19002 122 41.486 46.988 100550403 CHN CHN19001 122 45.319 48.858 100550405 CME CME30001 –13 16.336 19.305 100550406 CME CME30002 –13 16.336 19.31 100550407 ETH ETH09201 36 1.093 3.678 100550408 ETH ETH09202 36 1.12 3.824 100550409 GHA GHA10801 –25 14.071 17.877 100550410 GHA GHA10802 –25 14.071 17.882

230 Rep. ITU-R S.2365-0

TABLE 10-19 (end)

Low ID ADM Name Longitude High EPM EPM 100550444 IND INDA_102 55.8 24.403 31.767 100550443 IND INDA_101 55.8 24.403 31.771 100550411 IRN IRN10901 34 5.18 6.803 100550412 IRN IRN10902 34 5.964 9.951 100550414 IRQ IRQ25602 50 –0.179 2.182 100550413 IRQ IRQ25601 50 –0.179 4.633 100550418 MOZ MOZ30702 –1 10.019 11.355 100550417 MOZ MOZ30701 –1 10.019 12.165 100550420 NIG NIG11902 –19.2 4.158 9.5 100550419 NIG NIG11901 –19.2 4.158 9.515 100550422 NMB NMB02502 –18.8 4.481 9.879 100550421 NMB NMB02501 –18.8 4.481 9.896 100550423 NPL NPL12201 50 1.195 6.144 100550424 NPL NPL12202 50 1.195 28.926 107554004 PAK PAK12712 38 –14.681 5.809 100550425 PAK PAK12701 38.2 0.814 6.727 100550426 PAK PAK12702 38.2 0.822 14.719 100550428 PNG PNG13102 134 25.233 26.184 100550427 PNG PNG13101 134 25.233 26.189 100550430 SDN SDN__102 –7 26.094 29.46 100550429 SDN SDN__101 –7 26.094 29.466 100550431 SEN SEN22201 –37 39.623 42.481 100550432 SEN SEN22202 –37 39.623 42.488 100550434 SEY SEY00002 42.5 24.698 25.581 100550433 SEY SEY00001 42.5 24.698 26.405 100550435 SOM SOM31201 37.8 –0.359 1.867 100550436 SOM SOM31202 37.8 –0.357 3.456 100550438 TGO TGO22602 –30 14.14 15.933 100550437 TGO TGO22601 –30 14.14 15.938 100550440 USA USAC_102 140 18.555 34.668 100550439 USA USAC_101 140 18.555 34.673 100550441 YEM YEM__101 11 13.141 21.06 100550442 YEM YEM__102 11 13.707 23.683

Rep. ITU-R S.2365-0 231

10.2.1.3 Required coordination procedures As indicated before, if coordination procedures would be established between an FSS (Earth-to-space) allocation and the (existing) use of the band 14.5-14.8 GHz for feeder links for the BSS, the following elements would need to be considered in detail. Coordination scenarios: Based on the possible occurrences of coordination situations between an FSS allocation (E-s) in the band 14.5-14.8 GHz and allocations for feeder links for the BSS (as currently under RR No. 5.510), the following scenarios could be defined:

Scenario Coordination of With respect to 1 New assignment in the FSS band Receiving space station in Region 14.5-14.8 GHz (E-s) 1 and 3 feeder link Plan, List and pending Article 4 networks 2 Proposed new or modified Assignments in the FSS band assignment in Region 1 & 3 feeder 14.5-14.8 GHz (E-s) link List

Coordination threshold Based on existing threshold and criteria in AP 30A (such as § 2 to Annex 4), one of the options is to apply a threshold value of 6% for coordination for a new assignment in the FSS (E-s) allocation and an assignment in Region 1 and 3 feeder link Plan and List (14.5-14.8 GHz). Alternatively, an in line with other discussions that are currently on-going within WP 4A, mechanisms involving C/N or C/I calculations could also be considered. Similarly, as per section 6 in Annex 1 of AP 30A, the same options for a threshold could be explored for the coordination of a proposed new or modified assignment in Region 1 and 3 feeder link List with respect to an assignment in the FSS (E-s) allocation. In order to preserve the integrity of the feeder link Plan and its evolution in the 14.5-14.8 GHz in Regions 1 and 3 one of the possible regulatory solutions could be to obtain the explicit agreement from the affected countries having entries in the Region 1 and 3 feeder link Plan in the 14.5-14.8 GHz band if the protection criteria is not met by systems of Administrations intending to implement FSS in this band. In summary, compatibility between BSS feeder links and other FSS in the 14.5-14.8 GHz would be obtained through coordination proceduresthat need to be developed. Today, procedures are contained in RR AP 30A in respect of coordination between BSS feederlinks, and between BSS feeder links and unplanned FSS operating in the same frequency band. To obtain the same compatibility between BSS feederlinks and other FSS, similar criteria and coordination identification mechanisms could be included in Article 9 or AP 30A of the Radio Regulations.

10.2.1.3.1 Scenario 1: Coordination of New assignment in the FSS band 14.5-14.8 GHz (E-s) with Respect to Receiving space station in Region 1 and 3 feeder link Plan, List and pending Article 4 networks This section contains two studies analysing potential methods to trigger coordination between FSS systems and the BSS feeder link Plan and List assignments.

232 Rep. ITU-R S.2365-0

10.2.1.3.1.1 Study 3: Coordination Criteria for Coordinating FSS Systems (Earth to space) with respect to AP 30A Plan and List Assignments in the 14.5-14.8 GHz Band Introduction Following the guidance on consideration of the 14.5-14.8 GHz band on Resolution 152 (WRC-12), this Report proposes to apply a power flux density (pfd) limit as threshold for coordination for a new assignment in the FSS (E-s) allocation with respect to an assignment in Regions 1 and 3 feeder link Plan and List (14.5-14.8 GHz) (from now, “BSS feeder link”). The proposed pfd limit has been obtained considering that a new assignment in the FSS (E-s) allocation should not interfere to any existing BSS feeder link assignment more than a new BSS feeder link assignment would do. Following this idea, it is proposed as criteria for coordination that the power flux density produced by a new assignment in the FSS (E-s) allocation in the orbital position of any existing BSS feeder link assignment, has to be lower than –193.9 dB(W/(m2 · Hz)). Therefore, if a new assignment in the FSS (E-s) produces a pfd higher than –193.9 dB(W/(m2 · Hz)) in the orbital position of an existing BSS feeder link assignment, coordination between them will be required. Methodology The objective of the process described below is, through MSPACE simulations, find the maximum pfd that a new BSS feeder link assignment could produce in the orbital position of an existing BSS feeder link assignment and not “affect” it (considering as not affected when the equivalent protection margin (EPM) of the existing AP 30A assignment does not fall more than 0.45 dB below 0 dB, or, if already negative, more than 0.45 dB). Extrapolating, the pfd limit obtained will be proposed as threshold for coordination for a new assignment in the FSS (E-s) allocation with respect to any existing BSS feeder link assignment. Existing AP 30A assignments considered in the simulations To perform the calculations in the MSPACE simulations, have been considered as victim networks (MSPACE terminology) the AP 30A national assignments contained in the Plan.

TABLE 10-20 Satellite networks considered as victim networks (Plan assignments)

Receive Beampeak long_nom gain noise_t coordinates Adm sat_name beam_name (degrees) (dBi) (K) Longitude & Latitude (degrees) SEN22201 E001 SEN –37 42.63 750 –14.40 13.80 SEN22202 E001 TGO22601 E001 TGO –30 46.14 750 0.68 8.57 TGO22602 E001 GHA10801 E001 GHA –25 42.49 750 –1.20 7.90 GHA10802 E001

Rep. ITU-R S.2365-0 233

TABLE 10-20 (continued)

Receive Beampeak long_nom gain noise_t coordinates Adm sat_name beam_name (degrees) (dBi) (K) Longitude & Latitude (degrees) NIG11901 E001 NIG –19.2 38.05 750 7.80 9.40 NIG11902 E001 NMB02501 E001 NMB –18.8 37.41 750 17.50 –21.60 NMB02502 E001 CME30001 E001 CME –13 38.15 750 12.70 6.20 CME30002 E001 SDN__101 E001 29.60 18.40 SDN__102 E001 SDN –7 37.2 750 SDN__101 E001 29.90 9.80 SDN__102 E001 MOZ30701 E001 MOZ –1 37.52 750 34.00 –18.00 MOZ30702 E001 AFS02101 E001 AFS 4.8 37.24 750 24.50 –28.00 AFS02102 E001 YEM__101 E001 44.36 15.70 YEM__102 E001 YEM 11 47.78 750 YEM__101 E001 48.61 14.42 YEM__102 E001 IRN10901 E001 IRN 34 36.03 750 54.20 32.40 IRN10902 E001 ETH09201 E001 ETH 36 36.4 750 40.49 9.20 ETH09202 E001 SOM31201 E001 SOM 37.8 36.92 750 45.17 6.61 SOM31202 E001 PAK12701 E001 PAK 38.2 37.49 750 69.60 29.50 PAK12702 E001 SEY00001 E001 SEY 42.5 40.44 750 51.86 –7.23 SEY00002 E001 IRQ25601 E001 IRQ 50 40.58 750 43.86 32.86 IRQ25602 E001 NPL12201 E001 NPL 50 44.31 750 82.70 28.30 NPL12202 E001

234 Rep. ITU-R S.2365-0

TABLE 10-20 (end)

Receive Beampeak long_nom gain noise_t coordinates Adm sat_name beam_name (degrees) (dBi) (K) Longitude & Latitude (degrees) INDA_101 E001 76.20 19.50 INDA_102 E001 INDA_101 E001 77.44 15.73 INDA_102 E001 IND 55.8 45.66 750 INDA_101 E001 77.80 11.10 INDA_102 E001 INDA_101 E001 72.70 11.20 INDA_102 E001 KOR KOREASAT–1 116 E001 43.4 1000 127.5 36 CHN19001 E001 CHN 122 47.08 750 114.17 23.32 CHN19002 E001

PNG13101 E001 PNG 134 38.87 750 148.07 –6.65 PNG13102 E001 USAC_101 E001 152.50 11.70 USAC_102 E001 USA 140 44.06 750 USAC_101 E001 –157.50 21.00 USAC_102 E001

Simulations: Description of the process Step 1 To determine if a new BSS feeder link (interferer network) would “affect” to an existing BSS feeder link (victim network), a new interferer network was created with characteristics to produce maximum interference into its victim network: • To ensure that the earth station of the interferer network transmitted in the direction of the space station of its victim network, the orbital position of the interferer network was chosen as the same than its victim network. • To ensure that the space station of the victim network received the maximum interference from the earth station of the interferer network, any test point of the interferer network was chosen with the same geographical coordinates than the geographical coordinates of the reception diagram’s beam peak of its victim network. Rep. ITU-R S.2365-0 235

FIGURE 10-20 Representation of the MSPACE simulation scenario

Step 2 Through MSPACE simulations was determined whether the victim network was “affected” or not. If the results determined that the victim network was affected, the e.i.r.p. of the interferer network was reduced and the calculation was repeated. This process was repeated until the victim network was “not affected”. Step 3 The process described in steps 1 and 2 was repeated for all the victims networks considered Step 4 Among all the interferer networks, the one with the lowest e.i.r.p. transmitted was selected (“less interferer network”). It must be noted that this interferer network with this level of e.i.r.p. would not “affect” to any of the victim networks considered Step 5 From the e.i.r.p. of this “less interferer network”, the pfd that would produce in the orbital position of its victim network was calculated as: 푑퐸퐼푅푃 푊 푃퐹퐷 = 10 log ( ) 푑퐵( ) (10-1) 4휋푟2 푚2퐻푧 where: pfd: Power flux-density produced by the interferer network in the orbital position of the victim network d'e.i.r.p.: e.i.r.p. density transmitted by the earth station of the interferer network in the orbital’s position direction of the victim network.

236 Rep. ITU-R S.2365-0

r: Distance between the interferer earth station and the orbital position of the victim space station. It has been assumed in the calculations r = 36 000 km.

FIGURE 10-21 Representation of the pfd in a geostationary orbital position produced by an earth station transmitting a determined e.i.r.p. in the direction of that geostationary orbital position

Step 6 Finally, the pfd value calculated in Step 5 is the maximum pfd that a new BSS feeder link or new FSS assignment could produce in the orbital position of any of the existing BSS feeder link assignments considered in the simulations and not “affect” to it. Final results The pfd limit proposed as threshold for coordination, –193.9 dB(W/(m2 · Hz)), has been calculated following the method described in previous section It must be noted that, according to equation (1), an earth station transmitting an e.i.r.p. density of −31.8 dBW/Hz in the direction of a determined geostationary orbital location, produces a pfd at that geostationary orbital location of ‒193.9 dB(W/(m2 · Hz)). Impact of the pfd limit / e.i.r.p. density limit in the existing BSS feeder link assignments In this subsection is analysed the impact of new assignments in the FSS (E-s) allocation transmitting below the proposed coordination threshold (coordination would not be required), into the existing BSS feeder link assignments. To evaluate the impact, C/I calculations and MSPACE simulations are shown in Table 10-21 and Table 10-22. Where the wanted signals (C) and the Interferer signals (I) considered are: • Wanted Signals (C): – Table 10-21: AP 30A Plan national assignments considered as victim networks in the simulations – Table 10-22: Modifications to AP 30A, already included in the List. Rep. ITU-R S.2365-0 237

• Interferer Signals (I): – New assignments in the FSS (E-s) allocation transmitting in the limit of the coordination threshold proposed (Earth stations transmitting an e.i.r.p. density of ‒31.8 dBW/Hz in the direction of the wanted networks space stations).

TABLE 10-21 C/I and MSPACE calculations considering wanted networks as the AP 30A Plan assignments

Wanted: AP30A, National Assignments in the Plan Interferer

e.i.r.p. MSPACE density Affected? Gain Earth Power in the long_nom Satellite Station Spectral direction C/I Adm sat_name beam_name (degrees) Rx Gain Tx Density of the (dB) (dBi) (dBi) (dBW/Hz) desired network (dBW/Hz) SEN22201 E001 42.63 57 –49.3 –31.8 39.5 No SEN –37 SEN22202 E001 42.63 57 –49.3 –31.8 39.5 No TGO22602 E001 46.14 57 –49.3 –31.8 39.5 No TGO –30 TGO22601 E001 46.14 57 –49.3 –31.8 39.5 No GHA10801 E001 42.49 57 –48.3 –31.8 40.5 No GHA –25 GHA10802 E001 42.49 57 –48.3 –31.8 40.5 No NIG11902 E001 38.05 57 –49.3 –31.8 39.5 No NIG –19.2 NIG11901 E001 38.05 57 –49.3 –31.8 39.5 No NMB02502 E001 37.41 57 –49.3 –31.8 39.5 No NMB –18.8 NMB02501 E001 37.41 57 –49.3 –31.8 39.5 No CME30001 E001 38.15 57 –47.3 –31.8 41.5 No CME –13 CME30002 E001 38.15 57 –47.3 –31.8 41.5 No SDN_102 E001 37.2 57 –45.3 –31.8 43.5 No SDN –7 SDN_101 E001 37.2 57 –45.3 –31.8 43.5 No MOZ30702 E001 37.52 57 –49.3 –31.8 39.5 No MOZ –1 MOZ30701 E001 37.52 57 –49.3 –31.8 39.5 No AFS02102 E001 37.24 57 –49.3 –31.8 39.5 No AFS 4.8 AFS02101 E001 37.24 57 –49.3 –31.8 39.5 No YEM_101 E001 47.78 57 –49.3 –31.8 39.5 No YEM 11 YEM_102 E001 47.78 57 –49.3 –31.8 39.5 No IRN10902 E001 36.03 57 –49.3 –31.8 39.5 No IRN 34 IRN10901 E001 36.03 57 –49.3 –31.8 39.5 No ETH09201 E001 36.4 57 –49.3 –31.8 39.5 No ETH 36 ETH09202 E001 36.4 57 –49.3 –31.8 39.5 No SOM31201 E001 36.92 57 –48.3 –31.8 40.5 No SOM 37.8 SOM31202 E001 36.92 57 –48.3 –31.8 40.5 No PAK12701 E001 37.49 57 –49.3 –31.8 39.5 No PAK 38.2 PAK12702 E001 37.49 57 –49.3 –31.8 39.5 No

238 Rep. ITU-R S.2365-0

TABLE 10-21 (end)

Wanted: AP30A, National Assignments in the Plan Interferer

Rep. ITU-R S.2365-0 239

TABLE 10-22 C/I calculations considering as wanted networks the modifications to the AP 30A assignments, already included in the List

Wanted: AP30A modifications included in the List INTERF

e.i.r.p. MSPAC density E Earth Gain Power in the Affected? Station ad long_nom Satellite Spectral direction C/I* sat_name beam_name Gain m (degrees) Rx Density of the (dB) Tx (dBi) (dBW/Hz) wanted (dBi) network (dBW/Hz) SIRIUS-5E- S 5 14A 35 57 –45.2 –31.8 43.6 No BSS EUTELSAT F 9 NAFB 30 55.4 –50.5 –31.8 36.7 No B-9E DBL-G3- LUX 19.2 GBL 35 57 –48.2 –31.8 40.6 No 19.2E DBL-G3- LUX 23.5 GBL 35 57 –48.2 –31.8 40.6 No 23.5E DBL-G3- LUX 28.2 14G 35 57 –48.2 –31.8 40.6 No 28.2E DBL-G3- LUX 31.5 14G 35 57 –48.2 –31.8 40.6 No 31.5E ARABSAT ARS 44.5 ARAB1 35 57 –52.3 –31.8 36.5 No BSS 6F F-SAT-E- F 70.5 SR1R 36 55.4 –48.2 –31.8 39 No BSS-70.5E INTERSPUT RUS 74.9 GR 37 57 –49.4 –31.8 39.4 No NIK-74.9E-B CHNBSAT- CHN 92.2 TMO 4 62.3 –52.9 –31.8 41.2 No 92.2E KOR 113 KOREASAT-2 E001 43.4 57.3 –49.6 –31.8 39.5 No KOR 116 KOREASAT-1 E001 43.4 57.3 –49.6 –31.8 39.5 No KOR 116 KOREASAT-3 E001 43 57 –49.6 –31.8 39.2 No (*) Table 8-3 has been summarized and for each network only the worst C/I case is shown. C/I has been calculated as follows: 퐶 (푑퐵) = (푑푃푣 + 퐺푣, 푡푥 − 퐿푓푠 + 퐺푣, 푟푥) − (푑퐸퐼푅푃𝑖(θ푡푥) − 퐿푓푠′ + 퐺푣, 푟푥 (θ푟푥)) (10-2) 퐼 Considering that the wanted earth station and the interferer earth station transmit from the same point on the Earth: Gv,rx = Gv,rx (θrx) Lfs = Lfs’ Then: 퐶 (푑퐵) = (푑푃푣 + 퐺푣, 푡푥) − (푑퐸퐼푅푃𝑖(θ푡푥)) (10-3) 퐼

240 Rep. ITU-R S.2365-0 where: dPv: Power spectral density (dBW/Hz) transmitted by the earth station of the wanted network Gv,tx: Transmit gain (dBi). Earth station wanted network Gv,rx: Receive gain (dBi). Satellite station wanted network Lfs: Free space loss (dB) between the wanted earth station and the wanted space station d'e.i.r.p.i(θtx): e.i.r.p. density (dBW/Hz) transmitted by the Interferer network in the direction of the wanted space station Lfs’: Free space loss (Db) between the interferer earth station and the wanted space station Gv,rx (θrx): Receive gain (dBi) of the wanted space station in the direction to the earth station interferer. Tables 10-21 and 10-22 results clearly show that new assignments in the FSS (E-s), transmitting below the proposed coordination threshold, will produce low levels of interference into the existing BSS feeder link assignments. For all the BSS feeder link assignments currently included in the Plan and List, the C/I values are higher than 36.5 dB and not any of them would be “affected” according to the MSPACE results. Then, it can be stated that the proposed coordination threshold is adequate to protect the existing BSS feeder link assignments. Transmissions below the pfd limit / e.i.r.p. density limit Table 10-23 shows typical examples of transmission which would not exceed the coordination limits proposed. It must be noted that the Equivalent Orbital Separation has been calculated as: 퐸푞푢𝑖푣푎푙푒푛푡 푂푟푏𝑖푡푎푙 푆푒푝푎푟푎푡𝑖표푛 = 1.1 푥 푇표푝표푐푒푛푡푟𝑖푐 퐴푛푔푙푒

TABLE 10-23 Typical transmission examples which would not exceed the coordination limits proposed

Transmission examples Coordination Limits

Power Off Equivalent e.i.r.p. Antenna Spectral Topocentric axis Orbital density pfd limit Diameter Radiation Density Angle Gain Separation limit Diagram Transmitted

(m) (dBW/Hz) (degrees) (dBi) (degrees) (dBW/Hz) dB(W/(m2 • Hz)) 0.6 Rec. 580-6 –50 5.82 18.2 5.29 0.75 Rec. 580-6 –50 5.32 18.2 4.84 0.9 Rec. 580-6 –50 4.95 18.2 4.5 –31.8 –193.9 1.2 Rec. 580-6 –50 2.7 18.2 2.45 2.4 Rec. 580-6 –50 2.7 18.2 2.45

Examples shown in Table 10-23 are in line with typical operational parameters in the uplink FSS Ku-band. Rep. ITU-R S.2365-0 241

Conclusions In conclusion, a pfd limit of ‒193.9 dB(W/(m2 · Hz)) could be used as coordination criteria for coordination for a new assignment in the FSS (E-s) allocation with respect to an assignment in Regions 1 and 3 feeder link Plan and List in the 14.5-14.8 GHz band. Consideration could be given to treating protection of the Plan differently from List assignments.

10.2.1.3.1.2 Study 4: Methods to coordinate FSS systems and AP 30A Plan and List assignments This study analysed the potential for coordinating new FSS assignments in the 14.5-14.8 GHz band with the existing assignments in the AP 30A Plan and List. The objective of the study is to ensure the current and future protection of the Plan and List but also create a viable solution for new FSS systems. Prior to analysing coordination triggers, a check was performed to verify that the pfd produced by FSS transmitting earth stations at the GSO meet the maximum pfd limit allowed in AP 30A. This calculation is shown in the “Verification of max pfd at the GSO orbit” section. Two coordination triggers are considered in the “Method 1” and “Method 2” sections below: ΔT/T (6%), and a C/I criterion. The coordination triggers are evaluated and compared against one another. The results suggest that it is feasible for new FSS networks to be coordinated with Plan and List systems using these three procedures. Assumptions The characteristics used for this study are similar to those used in Study 1 (above) and are summarized below in Tables 10-24 and 10-25.

TABLE 10-24 Characteristics of FSS Systems

Parameters Assumed values Transmission Type Point-to-Point Wideband VSAT Earth station TX gain (dBi) 43.5 55.9 43.5 Earth station Antenna Efficiency 65% Carrier power (dBW) 18 25.5 11 Carrier bandwidth (MHz) 5.9 36 1.2 Space station antenna RX gain (dBi) 32 ITU R S.1855 ITU R S.1855 Earth station TX antenna pattern ITU-R S.1855 ITU-R BO.1213 ITU-R BO.1213 Satellite Station-Keeping 0.05°

242 Rep. ITU-R S.2365-0

TABLE 10-25 Characteristics of BSS Systems

Parameters Assumed values Satellite RX Gain (dBi) 32 Satellite Station-Keeping 0.1° System Noise Temperature (K) 750 Earth Station TX Gain (dBi) 57 Earth Station Input Power (dB) 25 Channel Bandwidth (MHz) 27

Note that it has been assumed that the FSS transmitting earth station is located in close proximity to the BSS transmitting earth station. Thus, the methods below are evaluated for the worst-case interference scenario since there is no gain advantage of the BSS satellite receive antenna. Verification of max pfd at the GSO orbit The geocentric orbital separation of the FSS and BSS satellite networks is assumed to vary between 1 and 9 degrees. At each interval, the corresponding pfd is calculated. Table 10-26 shows the pfd at the various orbital separations. AP 30A indicates that new or proposed assignments to the feeder-link List shall not exceed −76 dB(W/m2*27MHz). At all orbital separations, the pfd is below the maximum specified in AP 30A. Additionally, the pfd produced at the GSO by the FSS transmitting earth stations meet the threshold proposed in Study 1 of –193.9 dB(W/(m2 • Hz)) or –119.6 dB dB(W/(m2 • Hz)) for orbital separation angles of 3 degrees or greater.

Rep. ITU-R S.2365-0 243

TABLE 10-26 pfd (dB(W/m2 • 27 MHz)) at Orbital Separations between 1° and 9°

Separation Transmission Type (degrees) Point-to-Point Wideband VSAT 1 –101.6 –108.1 –101.7 1.5 –113.2 –113.1 –113.3 2 –116.2 –116.5 –116.3 2.5 –118.8 –119.1 –118.9 3 –120.9 –121.2 –121.0 3.5 –122.6 –123.0 –122.7 4 –124.1 –124.5 –124.2 4.5 –125.5 –125.8 –125.5 5 –126.6 –127.0 –126.7 5.5 –127.7 –128.1 –127.8 6 –128.7 –129.0 –128.8 6.5 –128.6 –129.9 –128.6 7 –128.8 –129.2 –128.9 7.5 –129.1 –129.4 –129.1 8 –129.3 –129.7 –129.4 8.5 –129.5 –129.9 –129.6 9 –130.2 –130.5 –130.3

Method 1: ΔT/T of 6% The following section considers the effects of using a ΔT/T coordination trigger both in terms of ensuring protection of the BSS feeder-links and allowing a viable solution for new FSS systems. The geocentric orbital separation of the FSS and BSS satellite networks is assumed to vary between 1 and 9 degrees. At each interval, the corresponding uplink ΔT/T is calculated for the BSS feeder link. Table 10-27 shows the ΔT/T percentages. Coordination is required in situations where the noise temperature of the feeder-link space station exceeds a threshold ΔT/T of 6%. The results of the study show that with the study parameters a separation of 4.5° is required in all cases to keep ΔT/T less than 6%.

244 Rep. ITU-R S.2365-0

TABLE 10-27 ΔT/T Percentages at Orbital Separations between 1° and 9°

Transmission Type Separation Point-to- (degrees) Wideband VSAT Point 1 1310.40% 293.50% 1285.50% 1.5 90.40% 92.30% 88.70% 2 45.60% 42.00% 44.70% 2.5 25.10% 23.10% 24.60% 3 15.50% 14.30% 15.20% 3.5 10.30% 9.50% 10.10% 4 7.30% 6.70% 7.20% 4.5 5.40% 5.00% 5.30% 5 4.10% 3.80% 4.00% 5.5 3.20% 3.00% 3.10% 6 2.60% 2.40% 2.50% 6.5 2.60% 1.90% 2.60% 7 2.50% 2.30% 2.40% 7.5 2.30% 2.20% 2.30% 8 2.20% 2.00% 2.20% 8.5 2.10% 1.90% 2.10% 9 1.80% 1.70% 1.80%

Method 2: C/I criterion The following section considers the effects of using a C/I criterion as a coordination trigger both in terms of ensuring protection of the BSS feeder-links and allowing a viable solution for new FSS systems. The geocentric orbital separation of the FSS and BSS satellite networks is assumed to vary between 1 and 9 degrees. At each interval, the corresponding C/I is calculated. Table 10-28 shows the C/I at the various orbital separations. AP 30A states that the latest revision of the plan the minimum co-channel single entry C/I ratio was 28 dB. The C/I calculations in the study show that this criteria is met for angles 1.5 degrees and larger for all transmission types. NOTE ‒ The 28 dB was used as a minimum single-entry C/I for replanning of the Regions 1 and 3 Plan at WRC-2000 (see section 3.3 of Annex 3 to Appendix 30A). Further iterations should consider the single-entry C/I that is equivalent to the single-entry EPM criteria in §4 of Annex 1 of AP30A for adding a new assignment to the List. I.e. the allowed single-entry C/I = Protection ratio (30 dB) + 9.6 (for 0.45 dB degradation in aggregate C/I)+current EPM (reference situation, if less than 0). Rep. ITU-R S.2365-0 245

TABLE 10-28 C/I (dB) at Orbital Separations between 1° and 9°

Transmission Type Separation Point-to- (degrees) Wideband VSAT Point 1 21.5 26.7 21.6 1.5 33.1 31.7 33.2 2 36.1 35.2 36.2 2.5 38.7 37.8 38.8 3 40.8 39.9 40.9 3.5 42.6 41.6 42.6 4 44.1 43.1 44.1 4.5 45.4 44.4 45.5 5 46.6 45.6 46.7 5.5 47.6 46.7 47.7 6 48.6 47.7 48.7 6.5 48.5 48.6 48.6 7 48.7 47.8 48.8 7.5 49.0 48.0 49.1 8 49.2 48.3 49.3 8.5 49.5 48.5 49.6 9 50.1 49.2 50.2

Results and comparisons This study investigated the impact of using ΔT/T (6%) and a C/I criterion as coordination triggers between the existing BSS feeder-links and possible new FSS uplinks in the 14.5-14.8 GHz band. In the worst-case scenario, the ΔT/T criteria would trigger coordination for satellite networks that were separated by less than 4.5 degrees. That is to say that BSS and FSS satellite networks separated by at least 4.5 degrees showed a ΔT/T of less than or equal to 6%. The C/I criteria is met for angles of 1.5 degrees and larger for all transmissions. Of the two coordination methods described in the study, it is recommended that a C/I criterion be used to trigger coordination between BSS and FSS systems using the 14.5-14.8 GHz band. It is the predominant method used in the coordination between FSS systems and can provide the appropriate coordination trigger needed to protect the AP 30A Plan and List assignments.

10.2.1.3.2 Scenario 2: Coordination of Proposed New or Modified Assignment in Regions 1 and 3 Feeder link List with respect to Assignments in the FSS Band 14.5-14.8 GHz (E-s) 10.2.1.4 Summary of Possible Coordination Triggers Feasibility of sharing between the AP30A Plan and List assignments and FSS (E-s) links has been established in the previous section. In order to ensure protection of the Plan and List assignments from new FSS (E-s) links, coordination triggers need to be defined. The coordination triggers proposed in the studies above are summarized below.

246 Rep. ITU-R S.2365-0

10.2.1.4.1 Method 1: pfd Coordination Trigger A pfd threshold is one of the methods proposed to be used a as trigger for coordination for a new assignment in the FSS (E-s) allocation with respect to an assignment in Regions 1 and 3 feeder link Plan and List. Specifically, it has been proposed that the power flux density produced by a new assignment in the FSS (E-s) allocation in the orbital position of any existing BSS feeder link assignment has to be lower than –193.9 dB(W/(m2 · Hz)). Therefore, if a new assignment in the FSS (E-s) produces a pfd higher than –193.9 dB(W/(m2 · Hz)) in the orbital position of an existing BSS feeder link assignment, coordination between them will be required. To obtain this pfd coordination limit, MSPACE simulations have been run to calculate the maximum pfd that a new BSS feeder link assignment could produce in the orbital position of an existing BSS feeder link Plan assignment and not “affect” it. An assignment is considered as not affected when the equivalent protection margin (EPM) of the existing AP 30A assignment does not fall more than 0.45 dB below 0 dB, or, if already negative, more than 0.45 dB. Extrapolating, the pfd limit obtained has been proposed as threshold for coordination for a new assignment in the FSS (E-s) allocation with respect to any existing BSS feeder link. To evaluate the impact that new assignments in the FSS allocation transmitting below the proposed coordination limit would have into the existing BSS Plan and List feeder link assignments, C/I calculations were performed and C/I values higher than 36.5 dB were found in all cases. Cumulative effect of multiple FSS new comers on a single AP30A Plan assignment was evaluated. MSpace was used to calculate this cumulative effect. The results of those calculations were used to obtain a pfd mask to be applied between 2 degrees and 9 degrees around the AP30A Plan assignment: 2 pfd = –185.1 – 25*log10(orbital separation) dB(W/(m · Hz)) This pfd mask would be used a threshold for coordination.

10.2.1.4.2 Method 2: ΔT/T Coordination Trigger A ΔT/T threshold is one of the methods proposed to be used to trigger coordination for a new assignment in the FSS (E-s) allocation with respect to an assignment in Regions 1 & 3 feeder link Plan and List. Specifically, it has been proposed that new FSS (E-s) systems that cause the ΔT/T of an AP30A Plan or List assignment to exceed 6% will require coordination. The 6% ΔT/T is the threshold currently used to trigger coordination between GSO systems in Appendix 5 and for coordination between networks defined in Annexes 1 and 4 of AP30A.

10.2.1.4.3 Method 3: C/I A Carrier-to-Interference (C/I) limit is one of the methods proposed to be used a as threshold for coordination for a new assignment in the FSS (E-s) allocation with respect to an assignment in Regions 1 and 3 feeder link Plan and List. Annex 3 section 3.3 to AP 30A states that no single-entry C/I ratio for an existing BSS feeder link Plan or List assignment should be lower than 28 dB. Therefore it is proposed that if a new assignment in the FSS (E-s) decreases the C/I of the Plan and List assignments below 28 dB, coordination between them will be required. NOTE ‒ The 28 dB was used as a minimum single-entry C/I for replanning of the Regions 1 and 3 Plan at WRC-2000 (see section 3.3 of Annex 3 to AP 30A). Further iterations should consider the single-entry C/I that is equivalent to the single-entry EPM criteria in section 4 of Annex 1 of AP 30A for adding a new assignment to the List. I.e. the allowed single-entry C/I = Protection ratio (30 dB) + 9.6 (for 0.45 dB degradation in aggregate C/I) + current EPM (reference situation, if less than 0). Rep. ITU-R S.2365-0 247

10.2.2 FSS (E-s) and FS This section reviews studies concerning sharing between FSS (Earth-to-space) and certain systems in the Fixed Service in the 14.5-14.8 GHz band. In the United States of America, low density radio communications links (LD-RCL) systems and television microwave link (TML) systems, operate in the 14.4-15.35 GHz fixed service (FS) band and are used as the fixed-point systems for point-to-point microwave links that carry data. FS station characteristics in the considered frequency band are given in Recommendation ITU-R F.758-5 ‒ System parameters and considerations in the development of criteria for sharing or compatibility between digital fixed wireless systems in the fixed service and systems in other services and other sources of interference, and are presented in Table 10-29 below.

TABLE 10-29

FS system parameters in the 14.4-15.35 MHz band

Frequency range (GHz) 14.4-15.35 Reference ITU-R Recommendation F.636 Modulation FSK 128-QAM Channel spacing and receiver noise bandwidth 2.5, 3.5, 7, 14, 28 2.5, 3.5, 7, 14, 28 (MHz) Tx output power range (dBW) 0 15 Tx output power density range (dBW/MHz) –5.44 0.528 Feeder/multiplexer loss range (dB) 0… 6.0 0… 5.0 Antenna gain range (dBi) 37 31.9 e.i.r.p. range (dBW) 31 … 37 41.9 … 46.9 e.i.r.p. density range (dBW/MHz) 25.6 … 31.6 27.4 … 32.4 Receiver noise figure typical (dB) 8

Receiver noise power density typical (=NRX) –136 (dBW/MHz) Normalized Rx input level for 1 × 10−6 BER –106.5 (dBW/MHz)

Nominal long-term interference power density NRX + I/N –136 + I/N (dBW/MHz)

The system parameters of the TML systems are provided in Table 10-30.

248 Rep. ITU-R S.2365-0

TABLE 10-30

TML System Parameters

Parameters Values Frequency range 14.4-15.25 GHz RF output power –8.2 dBW Receiver RF bandwidth1 –3 dB 45 MHz –20 dB 80 MHz –60 dB 270 MHz Receiver IF bandwidth1 –3 dB 44 MHz –20 dB 60 MHz –60 dB 120 MHz Receiver noise figure 10.5 dB Receiver tangential sensitivity –117 Antenna type Parabolic reflector, 4’ diameter Beamwidth @ –3 dB 1.4 × 1.4 deg Antenna gain 42.5 dBi Polarization H, V

For the purpose of establishing the sharing criteria between the systems of the fixed service (FS) and the proposed FSS (E-s), the antenna patterns are assumed to follow Recommendation ITU-R F.699-7 (reference radiation patterns for fixed wireless system antennas for use in coordination studies and interference assessment in the frequency range from 100 MHz to about 70 GHz) and the FS systems characteristics are assumed to follow Recommendation ITU-R F.758-5 (the FS system parameters for FS frequency sharing between 3 and 10 GHz). Recommendation ITU-R F.1094-2 lays the foundation for the apportionment of the performance and availability objectives, from which the long-term interference limit can be calculated. In the case of Rayleigh fading, it can be shown that if the aggregate level of interference is no higher than 10 dB below the receiver noise floor, the performance degradation will not exceed 10%. Also from Recommendation ITU-R F.758-5, by referencing interference to the receiver thermal noise level the problem is greatly simplified, independent of the modulation scheme of the victim system.

10.2.2.1 Study #1 The following two subsections will discuss the coordination distance based on the worst case calculation method (RR AP7) and the actual required separation distance in reality. The first is used to identify coordination requirements while the second may be used by administrations in bilateral coordination. The calculation of the maximum coordination distance identified by RR AP7 is based on most unfavorable assumptions regarding system parameter values and interference path geometry. Assuming all the worst-case values will occur simultaneously. In the case of sharing between FSS (Earth-to-space) and FS, this method is way too conservative since locations and characteristic of terminals are known. However, use of the AP7 can give an idea of the upper bound of the coordination distance, and through proper choice of the earth station locations, it may be possible to avoid international coordination. Rep. ITU-R S.2365-0 249

Assumptions Frequency 14.5-14.8 GHz Maximum power density –42 dBW/Hz, –46 dBW/Hz and –50 dBW/Hz Antenna gain 43.8 dBi (~ 1.2 m antenna) Satellite location 122E Antenna pattern Recommendation ITU-R S.580-6 Chosen locations Capital city of all APT member’s countries

10.2.2.1.1 Calculation method (Worst case assumption): RR AP7 Description for this calculation method: The determination of the coordination area is based on most unfavorable assumptions regarding system parameter values and interference path geometry. However, to assume that all the worst-case values will occur simultaneously will lead to unrealistically large distances to obtain the minimum required loss and hence unnecessarily large coordination areas. However, the use of AP7 can give an idea of the upper bound of the coordination distance. The procedures allow the determination of a distance in all azimuthal directions around a transmitting or receiving earth station beyond which the predicted path loss would be expected to exceed a specified value for all but a specified percentage of the time. This distance is called the coordination distance. When the coordination distance is determined for each azimuth around the coordinating earth station it defines a distance contour, called the coordination contour, that encloses the coordination area. It is important to note that, although the determination of the coordination area is based on technical criteria, it represents a regulatory concept. Its purpose is to identify the area within which detailed evaluations of the interference potential need to be performed in order to determine whether the coordinating earth station or any of the terrestrial stations, or in the case of a bidirectional allocation any of the receiving earth stations that are sharing the same frequency band, will really experience unacceptable levels of interference. Hence, the coordination area is not an exclusion zone within which the sharing of frequencies between the earth station and terrestrial stations or other earth stations is prohibited, but a means for determining the area within which more detailed calculations need to be performed. In most cases a more detailed analysis will show that sharing within the coordination area is possible since the procedure for the determination of the coordination area is based on unfavourable assumptions with regard to the interference potential.

10.2.2.1.2 Results based on the above assumptions and worst case calculation method The detail of the calculation results could be found in the end of this section, the result indicate that in many cases, coordination with the terrestrial service of another country may not be necessary if an administration place an FSS earth station in their capital city which is generally far from the neighbouring country. Further, the coordination distance would be reduced significantly by having a minimum horizontal elevation angle of 5 degrees. It should be noted that the calculations provided in the Table below are for illustrative purposes and in no way imply that any earth station deployment should be limited to the locations identified in this table.

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Calculation results using the RR AP7 method: Capital cities of all APT members’ countries were selected for calculation as an example

Max coordination Max coordination Probably affected Probably affected distance distance countries identified countries identified in all azimuthal in all azimuthal by RR AP7 by RR AP7 software directions directions when Horizontal Software when Horizontal when Horizontal elevation angle = when Horizontal Rain Antenna elevation angle = elevation angle = Latitude and 0 deg (km) elevation angle = No Adm Country Capital City Climate Elevation 0 deg (km) 5 deg (km) Longitude (Assume max pwr 5 deg Zone (Assume max pwr (Assume max pwr (Deg) density (Assume max pwr density density density = –42/–46/ = –42/–46/ = –42/–46/ –50 dBW/Hz) = –42/–46/ –50 dBW/Hz) –50 dBW/Hz) –50 dBW/Hz)

–42 –46 –50 –42 –46 –50 –42 –46 –50 –42 –46 –50 1 AFG Afghanistan Kabul 34°28'N E 21.82 197 176 154 PAK PAK PAK 105 105 105 PAK PAK PAK

69°11'E 2 AUS Australia Canberra 35°15'S K 39.97 172 151 129 – – – 113 102 102 – – –

149°08'E 3 BGD Bangladesh (People's Republic of) Dhaka 23°43'N N 45.15 235 161 134 IND IND IND 133 106 106 IND IND IND

90°26'E 4 BTN Bhutan (Kingdom of) Thimphu 27°31'N K 42.17 174 152 129 BGD BGD CHN 113 105 105 CHN CHN CHN

89°45'E CHN CHN IND IND IND IND IND IND NPL 5 BRU Brunei Darussalam Bandar Seri 04°52'N P 79.97 193 166 141 INS INS INS 131 114 114 INS INS INS

Begawan 115°00'E MLA MLA MLA MLA MLA MLA 6 CBG Cambodia (Kingdom of) Phnom Penh 11°33'N N 65.95 173 151 128 VTN VTN VTN 131 110 110 VTN VTN VTN

104°55'E 7 CHN China (People's Republic of) Beijing 39°55'N H 43.45 164 143 122 – – – 112 101 101 – – –

116°20'E 8 FJI Fiji (Republic of) Suva 18°06'S N 23.69 227 201 174 – – – 136 112 112 – – –

178°30'E 9 IND India (Republic of) New Delhi 28°37'N K 31.11 191 169 147 – – – 114 106 106 – – –

77°13'E 10 INS Indonesia (Republic of) Jakarta 06°09'S P 70.8 189 163 135 – – – 131 114 114 – – –

106°49'E 11 IRN Iran (Islamic Republic of) Tehran 35°44'N K 7.1 251 232 211 – – – 127 116 116 – – – 51°30'E 12 J Japan Tokyo 35°40'N K 44.51 181 155 129 – – – 113 102 102 – – – 139°45'E Rep. ITU-R S.2365-0 251

–42 –46 –50 –42 –46 –50 –42 –46 –50 –42 –46 –50 13 KIR Kiribati (Republic of) South Tarawa 1°23'N, N 31.43 213 186 160 – – – 134 120 120 – – – 173°09'E 14 KRE Democratic People's Republic of Pyongyang 39°2′N M 44.65 176 152 127 CHN – – 124 101 101 – – – Korea 125°45′E KOR 15 KOR Korea (Republic of) Seoul 37°31'N M 46.2 178 151 127 KRE KRE KRE 124 101 101 KRE KRE KRE 126°58'E 16 LAO Lao People's Democratic Republic Vientiane 17°58′N N 59.38 171 148 126 THA THA THA 132 107 107 THA THA THA 102°36′E 17 MLA Malaysia Kuala Lumpur 03°09'N P 69.35 184 157 130 INS INS INS 131 116 116 INS INS INS 101°41'E 18 MLD Maldives (Republic of) Male 04°00'N N 34.16 206 180 153 – – – 134 118 118 – – – 73°28'E 19 MHL Marshall Islands (Republic of the) Majuro 07°05' N P 33.23 201 181 155 – – – 134 116 116 – – – 171°08'E 20 FSM Micronesia (Federated States of) Palikir 06°55'N P 47.42 195 168 142 – – – 132 114 114 – – – 158°09'E 21 MNG Mongolia* Ulan Bator 47°55′N E 33.04 174 154 133 – – – 99 99 99 – – – 106°53′E 22 BRM Myanmar (Union of) Yangon 16°45'N P 54.65 190 162 135 – – – 132 109 109 – – – 96°20'E 23 NRU Nauru (Republic of) Yaren 0° 32’S 166° N 38.27 219 192 166 – – – 133 119 119 – – – 55’E 24 NPL Nepal (Federal Democratic Kathmandu 27°45'N K 38.43 179 157 135 CHN CHN CHN 113 105 105 CHN CHN CHN Republic of) 85°20'E IND IND IND IND IND IND 25 NZL New Zealand Wellington 41°19'S K 18.81 219 194 169 – – – 115 103 103 – – – 174°46'E 26 PAK Pakistan (Islamic Republic of) Islamabad 33°40'N E 25.38 197 176 155 IND IND IND 104 104 104 IND IND IND 73°10'E

252 Rep. ITU-R S.2365-0

–42 –46 –50 –42 –46 –50 –42 –46 –50 –42 –46 –50 27 PLW Palau (Republic of) Koror 07°20'N P 73.04 202 175 148 – – – 131 113 113 – – – 134°28'E 28 PNG Papua New Guinea Port Moresby 09°24'S P 58.78 188 163 135 – – – 132 113 113 – – – 147°08'E 29 PHL Philippines (Republic of the) Manila 14°40'N N 72.73 185 158 131 – – – 131 109 109 – – – 121°03'E 30 SMO Samoa (Independent State of) Apia 13°50'S D 14.7 245 222 196 SMA SMA SMA 140 118 118 – – – 171°50'W 31 SNG Singapore (Republic of) Singapore 01°14'N P 68.74 190 163 135 INS INS INS 131 117 117 INS INS INS 103°55'E MLA MLA MLA MLA MLA MLA 32 SLM Solomon Islands Honiara 09°27'S P 44.92 195 168 142 – – – 133 114 114 – – – 159°57'E 33 CLN Sri Lanka (Democratic Socialist Sri 6°54′N 79°54′E N 40.89 190 163 140 – – – 133 115 115 – – – Republic of) Jayawardenapura Kotte 34 THA Thailand Bangkok 13°45'N N 60.45 184 160 133 BRM – – 132 109 109 – – – 100°35'E 35 TON Tonga (Kingdom of) Nuku'alofa 21°10'S N 15.77 239 212 186 – – – 139 114 114 – – – 174°00'W 36 TUV Tuvalu Funafuti 08°31'S N 24.48 238 211 185 – – – 135 116 116 – – – 179°13'E 37 VUT Vanuatu (Republic of) Port-Vila 17°45'S P 33.95 217 191 165 – – – 134 110 110 – – – 168°18'E 38 VTN Viet Nam (Socialist Republic of) Hanoi 21°01'N N 59.28 184 156 129 CHN CHN – 132 106 106 – – – 105°50'E LAO LAO

* Mongolia is a Region 1 country, while all other 37 countries are Region 3 countries.

Rep. ITU-R S.2365-0 253

In practice, FSS (Earth-to-space) and FS has had long good sharing experience, many of the band allocated to FSS (Earth-to-space) are shared with FS. According to Recommendation ITU-R SF.1006, “experience has shown that, in many instances, separation distances as small as a few kilometres, when allowing for typical terrain and shielding, are achievable”. The actual required separation distance between the FS transmitter and the FSS station depends on the actual parameters of both systems, such as FS transmitter power density, minimum operational elevation angles of satellite systems, off-axis antenna gain of both systems, and the terrain topography. Mitigation techniques could be used to improve the required separation, although it should be noted that implementing a mitigation technique might be a burden for the administration. On the conditions that the location of FS stations are known, the deployment of FS terminals are not ubiquitous and both FSS (Earth-to-space) and FS station are operated under license, with only as small as few kilometers of separation distance in many instances, sharing between FS and FSS can be considered feasible. In the case where international coordination is unavoidable, experience indicate that the actual required separation distances is significantly shorter than the coordination distance calculated using the RR AP7 method, it is therefore expected the coordination should not lead to a heavy burden to the administration.

10.2.2.2 Study #2 The FS antenna gain patterns at 14.6 GHz, specified to follow the Recommendation ITU-R F.699-7, for three antennas with maximum antenna gains of 15, 30, and 40 dBi, are plotted in Fig. 10-22 as function of the off-axis angles.

FIGURE 10-22 FS Antenna Gain Patterns

FS Antenna Gain Pattern (ITU-R F.699-7) at 14.6 GHz 40 G = 15 dBi max 35 G = 30 dBi max 30 G = 40 dBi max

FS antenna FSgain, dBi antenna 5

-5

-10 0 10 20 30 40 50 60 70 80 90 Off-axis angle, deg

Based on the FS characteristics and using an interference level of I/N = –10 dB (Recommendation ITU-R F.758-5), the derived interference assessment in power spectral density (PSD) (dBW/MHz) for the FS is shown in Fig. 10-23. This calculation assumes feeder/multiplexer loss of 0 dB, 3 dB polarization loss, a 8 dB FS receiver noise figure, and the FS antenna gain (at a carrier frequency of 14.6 GHz) for off-axis arrival angles from 0 degree to 90 degrees.

254 Rep. ITU-R S.2365-0

FIGURE 10-23 FS interference protection threshold – Power spectral density (dBW/MHz)

FS w/ NF = 8 dB, Feeder Loss = 0 dB, Polarization Loss = 3 dB, I/N = -10 dB -135

-140

-145

-150

-155 For FS Station w/ G = 15 dBi -160 max For FS Station w/ G = 30 dBi max -165 For FS Station w/ G = 40 dBi max FS PSD, dBW / MHz -170

-175

-180

-185 0 10 20 30 40 50 60 70 80 90 Off-axis angle, deg

Since stations operating in the fixed service have the following characteristics: − location and characteristics are known; − is deployed between specified fixed points; − operate under license. These three characteristics significantly ease the case of FSS (E-s) earth stations (ES) sharing the same frequency band with FS systems, with FSS ES proper planning and mitigation techniques and that could effectively reduce the interference from FSS terminal into FS stations. Radio Regulations Appendix 7 should be used to determine the coordination area, such that the maximum aggregate interference power density (dBW/MHz) from all FSS earth stations to a FS station is below all FS PSD protection masks shown in Fig. 10-23. System parameters required for the determination of coordination distance for a transmitting FSS ES sharing with FS receiving terrestrial station in the 12.5-14.8 GHz frequency band in Table 7b of RR Appendix 7 should be used to determine the coordination area between FSS ES and FS receiving terrestrial station in the 14.4-15.35 GHz frequency band. Figure 10-24 shows the required coordination/separation areas (using Recommendation ITU-R P.452-14 with p = 0.0025%) for representative FS systems from FSS VSAT earth stations, where the maximum coordination distance and the azimuth radial for each system site are shown as a “blue” line to the site: a) Top plot for VSAT RFI into the mainbeam of FS systems with max antenna gain of 36 dBi, b) Middle plot for VSAT RFI into the mainbeam of FS systems with max antenna gain of 43 dBi, c) Next to bottom plot for VSAT RFI into the mainbeam of FS systems with max antenna gain of 52 dBi, and d) Bottom plot for VSAT RFI into the FS backlobe antenna gain of −4 dBi. Rep. ITU-R S.2365-0 255

FIGURE 10-24 FSS VSAT ES & FS – Coordination Areas

120 W 100 W 80 W 50 N

40 N

VSAT ES xPSD = -42 dBW/Hz xG = 43.5 dBi 30 N rG = 36 dBi Max Dist = 328 km p = 0.0025%

120 W 100 W 80 W 50 N

40 N

VSAT - ES xPSD = -42 dBW/Hz xG = 43.5 dBi 30 N rG = 43 dBi Max Dist = 363 km p = 0.0025%

256 Rep. ITU-R S.2365-0

120 W 100 W 80 W 50 N

40 N

VSAT - ES xPSD = -42 dBW/Hz xG = 43.5 dBi 30 N rG = 52 dBi Max Dist = 457 km p = 0.0025%

120 W 100 W 80 W 50 N

40 N

VSAT ES xPSD = -42 dBW/Hz xG = 43.5 dBi  30 N rG = - 4 dBi Dist = 69 - 220 km p = 0.0025%

10.2.3 FSS (E-s) and aeronautical mobile service (AMS) The 14.5-15.35 GHz frequency range is allocated to the fixed and mobile services on a primary basis in all three ITU Regions. Aeronautical mobile data links currently operate in the 14.5-15.35 GHz band under the mobile service (MS) allocation. The 14.5-14.8 GHz frequency band is also allocated to the FSS (Earth-to-space) on a primary basis in all three ITU Regions limited to feeder links for the broadcasting satellite service for administrations outside Europe.

10.2.3.1 System characteristics and hypothesis of the studies Table 10-31 provides a summary on the transmitting FSS earth station characteristics used in the different studies. Rep. ITU-R S.2365-0 257

TABLE 10-31 FSS earth station parameters

Parameter Study #1 Study #2 Study #3 Study #4/4A Study #1A Study #5 Study #6 Frequency GHz 14.6 14.6 14.6 14.6 14.6 14.7 14.6 Transmitted bandwidth MHz 0.354 0.354 10 36 0.354 0.8/36 0.354 Antenna min. elevation deg 10 10 10 10 10 10 17.52 angle (θt) Antenna diameter m 1.2 0.75 6 1.2, 2.4, 6 1.2 2.4, 6 2.4, 6 Antenna height above m 15 10 10 10 15 15 15 the terrain Rec. BO.1213* S.1855/ Antenna pattern (GT) BO.1213* S.580-6 S.465 BO.1213* S.465 ITU-R /S.1855 S.465 42.7, 49.4, Antenna peak gain (G0t) dBi 42.7 39.3 57.4 42.7 49.4, 57.4 49.1, 57.1 57.4 Variable Variable Variable Variable dBW/ −42; −50; ‒49.3, Transmit PSD −57 ‒50 ‒50 ‒49 ‒50 Hz −55; −59 ‒57 NOTE 1 – The transmit PSD of –42 dBW/Hz is derived from Recommendation ITU-R S.728. This level is 8 dB higher than one known administration’s domestic rules for routine licensing of VSAT earth stations. NOTE 2 – The transmit PSD of –57 dBW/Hz is derived from the mean of one satellite operators peak PSD levels that are in operation today in the 14-14.5 GHz band. The ‒57 dBW/Hz as the mean is derived from a methodology that may notably underestimate the mean. In study #2, a single earth station is modelled, however, since it is operating at 100% of the time, it could overestimate the interference from a single earth station that operates less than 100% of the time. NOTE 3 – The antenna height of 15 m may be higher than what is typically used for VSAT terminals.

Table 10-32 summarizes the receiving AMS station characteristics and the propagation model used in the different studies.

* This Recommendation ITU-R BO.1213 was used in the studies because it has improved main lobe and side lobe performance for small antennas and provides reference antenna patterns for BSS Receiving earth stations in the 11.7-12.75 GHz band; nevertheless studies 1, 2 and 1A use this pattern for FSS transmission.

258 Rep. ITU-R S.2365-0

TABLE 10-32 AMS receiving station parameters

Parameter Study #1 Study #2 Study #3 Study #4/4A Study #1A Study #5 Study #6 Carrier Not MHz 0.354 0.354 36 0.354 0.8/36 3.5 bandwidth provided

M.1851 M.1851 M.1851 M.1851 Quasi- Quasi- Antenna ITU-R Uniform Uniform Uniform S.465 Uniform omni omni pattern Rec. distrib. distrib. distrib. distrib. (System 6) (System 6) Antenna dBi 27 24 24 Not provided 27 3 3 peak gain

Propagation ITU-R Not Not P.528 P.528 Free space P.528 P.528 model Rec. provided provided

Terrain No Yes No Yes No No Yes model

10.2.3.2 Study #1 The VSAT/FSS earth station parameters assumed are provided in Table 10-31. These parameters are based on the FSS earth station characteristics shown above in § 4 of this Report. Study #1 examines the potential interference from a VSAT earth station operating in the FSS (here after referred to as VSAT) into an AMS station and estimates the required separation distance for protection of AMS aircraft. ITU Region 1is examined through one representative AMS locations. For the representative location, the analysis determines appropriate non-uniform area within which a FSS earth station has the potential of causing harmful interference. The AMS aircraft protection criteria used in this analysis is given in Recommendation ITU-R M.2068 as an I/N of –6 dB. The interference from a FSS transmitter into the AMS aircraft receiver normally arises under a radio- line of sight (LOS) propagation condition but it can also occur beyond LOS condition. Furthermore, a frequency of 14.6 GHz was assumed and the VSAT transmit antenna is assumed to be mounted on a tower for Study #1, with the transmit e.i.r.p. towards the received victim station is calculated using the given parameters. Figure 10-25 shows the potential interference scenarios (in dotted lines) to AMS aircraft link, AMS ground station link and FSS Satellite (GSO). Two cases are analysed: Case 1 – due to the visibility between these two links into AMS aircraft and AMS ground station, the interference link to AMS aircraft presents a worst case, so only this interfering link will be discussed further in this Report; Case 2 – AMS Interference into FSS Satellite (GSO). Rep. ITU-R S.2365-0 259

FIGURE 10-25 Interference scenarios from proposed VSAT station to AMS aircraft and AMS ground station

FSS VSAT Interfering into AMS systems AMS Systems Interfering into FSS Satellite GSO

10.2.3.2.1 Study #1 Representative AMS Locations The AMS aircraft may operate anywhere in ITU Region 1. Representative locations to be analysed in ITU Region 1 analysed are given in Table 10-33.

TABLE 10-33 Sample AMS locations in three ITU Regions operating in the 14.5-15.35 GHz band

Latitude Longitude Representative Location Country Region (deg N) (deg E) Cambridgeshire England 1 52.37 –0.23

10.2.3.2.2 Study #1 FSS and AMS aircraft parameters & analysis assumptions The AMS aircraft parameters used in the simulations are given in Table 10-34.

260 Rep. ITU-R S.2365-0

TABLE 10-34

Parameters used for AMS Value Units Notes aircraft Frequency 14.6 GHz Assumed the same received frequency for all stations and transmitting frequency for FSS Bandwidth N/A MHz The received bandwidth is at least 354 kHz. The FSS transmitted bandwidth is assumed to be at least as great as the minimum AMS aircraft’s bandwidth. Aircraft height Minimum: 2.4; km From dish center to ground; Maximum: 19 Height above the terrain Maximum antenna gain 27 dBi Document 4A/147 Antenna Radiation Rec. ITU-R M.1851 Uniform distribution Pattern Transmitted Power 0 dBW Document 4A/147 I/N permissible –6 dB Document 4A/147 interference level Noise figure 4 dB Document 4A/147 Probability of 1 % Using Rec. ITU-R P.528 propagation model exceedence (p) due to weather statistics

The minimum propagation loss, Lmin in dB, required from the VSAT transmitter to the AMS aircraft receiver is given by:

퐿푚푖푛 = 푒. 𝑖. 푟. 푝.푇푥− 푃푟표푡푒푐푡𝑖표푛퐶푟푖푡푒푟푖푎푅푥 + 퐺푅푥 − 푁 e.i.r.p.Tx is the spectral density transmitted in any direction towards the victim receiver station by the VSAT. The protection criterion for the AMS aircraft/AMS station is I/N of –6 dB. The received victim antenna gain, Grx, is an off-boresight gain toward the interfering a VSAT station. N is the received victim noise temperature. Using the above parameters, the minimum propagation loss to meet the protection of the AMS aircraft is dynamically calculated at every coverage grid point. Other simulation assumptions are as follows: 1) A VSAT station may communicate with any GSO satellite on the GSO arc with a minimum of 10 degrees elevation angle. 2) Assumed that the victim AMS aircraft and its corresponding AMS station may be in any orientation with respect to a VSAT. 3) Only one interfering VSAT is used. Multiple VSAT’s, transmitting to the same satellite on the same frequency, can generate aggregate interference that could potentially be higher than what is calculated in this contribution depending upon the actual VSAT density and geographical distribution. It should be noted, however, that VSAT earth stations that are part of the same system typically share a narrow bandwidth (< 2 MHz) on a time division basis, and typically operate at lower power densities than –42 dBW/Hz. 4) The area of analysis is sampled at 5  5 km. Rep. ITU-R S.2365-0 261

5) Employed Recommendation ITU-R P.528 propagation model with a 30 arc second (1 km) resolution global terrain data, and ITU Digitized World Map (IDWM) for interference into AMS aircraft. 6) Areas where the interference value is greater than the recommended threshold are colored in red and areas where the interference is below the required threshold are not colored.

10.2.3.2.3 Study #1, Case1: FSS Earth Station Interference into AMS aircraft The simulation result for one representative station is shown in Fig. 10-27 below. Due to the terrain height at different geographic areas resulting in a longer line of sight (LOS) distance, the results are typically worse than for the smooth earth case. The maximum value of the minimum required separation for the representative location, which is located in ITU Region 1, and not accounting for terrain obstruction, ranges up to 576 km for AMS at a 19 km altitude.

TABLE 10-35 Maximum value of the minimum required separation distances between VSAT and AMS aircrafts in the 14.5-15.35 GHz band

Figure 10-26 shows the AMS aircraft 19 km altitude coordination contour, not accounting for terrain obstruction, around Cambridgeshire, England. To meet the AMS aircraft protection criteria, the required separation distance for VSAT transmitters ranges up to approximately 576 km.

FIGURE 10-26 Coordination contour around Cambridgeshire, England, No Terrain (AMS aircraft at 19 km)

262 Rep. ITU-R S.2365-0

10.2.3.2.4 Study #1, Case 2: AMS aircraft/AMS station interference into FSS GSO Summary As shown in Fig. 10-26, there can be a number of geometries between an AMS ground station and AMS aircraft and between two AMS aircrafts, even if this time period is very limited. Since the AMS aircraft/AMS ground station’s antenna can vertically track the AMS aircraft, there will be times at which the AMS aircraft/AMS ground station’s antenna beam can be pointing at or near a satellite in the geostationary satellite orbit. During periods when the AMS aircraft and AMS station in the main beam of FSS GSO, the FSS GSO receiver may receive levels of interference that exceed the –6 dB interference threshold if the band is allocated to the FSS in the Earth-to-space direction. The G/T of a receiving space station in the GSO is required to calculate the I/N produced by AMS aircraft/AMS station into a GSO satellite receiver. As indicated in Table 10-32 above, Annex 10 to Document 4A/343 does not provide typical G/T values of GSO space station receivers in this portion of the spectrum. A partial survey of the most recent notifications of satellite networks listed in the ITU-R’s Space Network Systems (SNS) database was conducted over a range of longitudes in the three ITU Regions. A range of typical values was assumed for this analysis in terms of the highest (17 dBK–1), median (7 dBK–1) and lowest (−6 dBK–1) G/T values, designated as Case (a), Case (b) and Case (c), respectively, as indicated from the data in Table 10-36.

TABLE 10-36 GSO Space Station G/T Values

GSO arc Networks Maximum G/T Median G/T Minimum G/T Region examined considered Case (a) Case (b) Case (c) 1 –5° – 35° East 49 16.9 dBK–1 9.37 dBK–1 –6.61 dBK–1 2 –120° – 75° East 43 13.22 dBK–1 4.27 dBK–1 –6.6 dBK–1 3 70° – 130° East 73 22.01 dBK–1 7.59 dBK–1 –6.13 dBK–1 Typical values assumed for analysis 17 dBK–1 7 dBK–1 –6 dBK–1

Link calculations are presented in Table 10-37 for each of these cases, a satellite channel bandwidth of 10 MHz for calculating satellite receiver noise power. The resulting I/N calculated under free space propagation conditions is compared to an FSS space station I/N threshold of –12.2 dB, corresponding to the ∆T of 6% for 100% of the worst month criterion of Recommendation ITU-R S.1432. As indicated in the table, this I/N threshold is exceeded in 4 of the 6 examples presented in the Table 10-37. Rep. ITU-R S.2365-0 263

TABLE 10-37 Calculation of interference from AMS aircraft/AMS station into GSO space station receiver AMS Aircraft Tx -> FSS GSO Rx AMS earth station Tx -> FSS GSO Rx

Case (a)- Case (a)- Case (b)- Case (c)- Case (b)- Case (c)- Parameter G/T of G/T of Units G/T of 7.00 G/T of -6.0 G/T of 7.00 G/T of -6.0 17.00 17.00 Elevation Angle 5 5 5 5 5 5 degrees GSO distance 41,127 41,127 41,127 41,127 41,127 41,127 km Frequency 14.5 14.5 14.5 14.5 14.5 14.5 GHz Free Space Loss 207.95 207.95 207.95 207.95 207.95 207.95 dB Tx Power 1 1 1 1 1 1 watts Tx Antenna Gain 27.00 27.00 27.00 44.00 44.00 44.00 dBi Tx Interf Bandwidth 0.354 0.354 0.354 0.354 0.354 0.354 MHz Rx GSO G/T 17.00 7.00 -6.00 17.00 7.00 -6.00 dBK-1 Rx GSO Bandwidth 10.00 10.00 10.00 10.00 10.00 10.00 MHz I/N -5.15 -15.15 -28.15 11.85 1.85 -11.15 dB I/N threshold -12.2 -12.2 -12.2 -12.2 -12.2 -12.2 dB

Exceeding I/N threshold value 7.05 #N/A #N/A 24.05 14.05 1.05 dB

AMS Aircraft Tx → FSS GSO Rx AMS earth station Tx → FSS GSO Rx

Parameter Case (a) Case (b) Case (c) Case (a) Case (b) Case (c) Units G/T = 17 dB G/T = 7 dB G/T = –6 dB G/T = 17 dB G/T = 7 dB G/T = –6 dB Distance FSS GSO 41,127 41,127 41,127 41,127 41,127 41,127 km – FSS Es Frequency 14.5 14.5 14.5 14.5 14.5 14.5 GHz Free Space Loss 207.95 207.95 207.95 207.95 207.95 207.95 dB AMS Tx Power9 0 0 0 1 1 1 dBW AMS on-axis gain 27 27 27 44 44 44 dBi AMS Carrier 0.354 0.354 0.354 0.354 0.354 0.354 MHz Bandwidth GSO FSS G/T 17 7 –6 17 7 –6 dB/K FSS carrier 10 10 10 10 10 10 MHz Bandwidth I/N –5.35 –15.35 –28.35 12.65 2.65 –10.35 dB I/N threshold –12.2 –12.2 –12.2 –12.2 –12.2 –12.2 dB I/N exceedance 6.85 –3.15 –16.15 24.85 14.85 1.85 dB

In some cases, satellite antenna discrimination is required to protect GSO satellite receivers from AMS aircraft/AMS station emissions since antenna pointing restrictions on AMS aircraft/AMS station antennas is not practical.

9 Limits of RR Article 21 (§ 21.2, 21.3 and 21.5) apply.

264 Rep. ITU-R S.2365-0

10.2.3.2.5 Study #1 Summary for VSAT in the FSS and AMS Sharing With respect to interference into AMS systems operating in the 14.5-15.35 GHz band, there is a potential for interference from the proposed 14.5-15.35 GHz FSS/ VSAT Earth-to-space allocation to AMS aircraft receivers when a VSAT is in vicinity of the AMS aircraft. It is necessary that interference to the AMS aircraft in the 14.5-15.35 GHz be such that the protection is not exceeded. The separation distances resulting in a non-uniform area to protect a representative location in ITU Region 1 is shown in Table 10-35 above in order to meet an I/N criteria of –6 dB. Due to the terrain height at different geographic areas resulting in a longer line-of-sight (LOS) distance, the results are typically worse than for the smooth earth case. It is to be noted that this analysis is based on the presence in the area of a single VSAT operating on a single channel. The analysis shows that in order to protect the AMS receiver operating in the 14.5-15.35 GHz band in ITU Region 1, a separation distance of up to 576 km (not accounting for terrain obstruction) describes a non-uniform area around an AMS receiver where the protection criteria is exceeded. The terminal on the ground of the AMS can either be fixed or mobile. When the AMS system moves, so does the associated non-uniform area. In order to ensure the protection for current and future MS operations, the protection criteria within this non-uniform area must be met. With respect to interference into FSS GSO, since the main beams of such AMS systems can point toward the GSO, FSS space stations may be subject to unacceptable levels of interference over periods of time from AMS systems operating under the existing primary allocation in this band. This should be taken into account in developing any methods.

10.2.3.3 Study #1A The Study #1A analysis examines potential interference to AMS operating in the 14.5-15.35 GHz band resulting from FSS earth station uplinks. The AMS aircraft protection criteria used in this analysis is given in Recommendation ITU-R M.2068 as an I/N of –6 dB.

10.2.3.3.1 Study #1A Case 1: FSS Earth Station Interference into AMS aircraft As the I/N value depends on the respective position of the AMS station, the AMS aircraft, the FSS earth station and the FSS GSO satellite, this study assesses the zone within which the AMS aircraft would suffer from harmful interference for doing so, this study considers all other positions as fixed. According to the results of the Study #1, the required separation distance from an FSS earth station of 1.2 m with a PSD of –50 dBW/Hz and the AMS ground station is equal to 564 km. In other words, when the FSS earth station is located at 564 km from the AMS ground station, there exists at least one AMS aircraft position where the I/N value exceed the required protection threshold. Therefore, it is very important to assess the AMS aircraft area where the protection threshold is exceeded. In this study, the same parameters for the FSS earth station, AMS aircraft and AMS ground station as the Study #1 parameters are used (see Table 10-34). The AMS ground station is located in Cambridgeshire (England) and the area of analysis is sampled at 20  20 km. Several analyses are performed considering different FSS earth station offset relative to AMS ground station (see Table 10-38 below) communicating with an AMS aircraft having an altitude of 19 km. To assess the area where should be located the AMS aircraft (for the protection criteria to be exceeded) i with respect to position of the FSS earth station, several analyses are performed considering different FSS earth station position relative to AMS ground station (see Table 10-38 below) communicating with an AMS aircraft station flying at an altitude of 19 km. Rep. ITU-R S.2365-0 265

TABLE 10-38 FSS earth station offset with respect to AMS ground station in the different cases

AMS ground station FSS earth station Case Distance from number Latitude (° N) Longitude (° E) Latitude (° N) Longitude (° E) AMS ground station 1 52.37 –0.23 49.542 4.720 500 km 2 52.37 –0.23 49.824 4.225 450 km 3 52.37 –0.23 50.107 3.730 400 km 4 52.37 –0.23 50.673 2.740 300 km 5 52.37 –0.23 51.239 1.750 200 km 6 52.37 –0.23 51.804 0.760 100 km

For each of these cases, the AMS aircraft at 19 km in altitude is located at each position (sampled at 20 × 20 km) within a circle of 577 km radius around the AMS ground station. Terrain data for this area was not included in the analysis. The I/N value is computed at each AMS aircraft location. Figure 10-27 below shows the area (red zone) where the AMS aircraft should be located in order to not respect the I/N threshold considering a specific location of the AMS ground station and FSS earth station with an indication of the elevation angle of the AMS aircraft as seen by the AMS ground station. This red zone should be understood as area where the I/N value exceed the required protection threshold.

FIGURE 10-27 AMS aircraft impacted location

Case 1 (550 km) Case 2 (500 km)

266 Rep. ITU-R S.2365-0

Case 3 (450 km) Case 4 (400 km)

Case 5 (300 km) Case 6 (200 km)

Table 10-39 below show the maximum elevation of AMS aircraft and the percentage of total area (i.e. area where the AMS aircraft is in line of sight of the AMS ground station) where the I/N criteria is exceeded regarding the FSS Earth Station offset with respect to AMS ground station. Depending of the terrain profile, the AMS ground station may or may not be able to see the AMS aircraft due to natural/house obstacles with low elevation angles.

Rep. ITU-R S.2365-0 267

TABLE 10-39 FSS earth station position t with respect to AMS ground station in the different cases

Maximum FSS earth station Percentage of Area where elevation angle offset with respect to total area where I/N criteria is of AMS aircraft AMS ground station I/N criteria is exceeded with I/N criteria (km) exceeded (km2) exceeded 550 0.1° 0.05% 475 500 0.5° 0.15% 1 178 450 1.0° 0.45% 2 863 400 1.5° 1.10% 5 529 300 3.0° 2.31% 6 531 200 10.0° 5.57% 7 000

10.2.3.3.2 Study #1A Case 2: AMS aircraft/AMS station Interference into FSS GSO Station Study #1 assesses the potential interference from an AMS transmission towards a FSS GSO receiver, using a static analysis and only considers the worst case configuration (AMS station, AMS aircraft and FSS GSO satellite aligned). As the AMS aircraft is, by definition, moving, such worst case configuration will rarely occur. Therefore, in order to assess the potential interference from AMS transmission towards FSS GSO receivers, a dynamic analyses is performed. This study considers the dynamic nature of the aeronautical mobile service and the FSS earth station transmissions. This considers the interference from a transmitting AMS station into FSS GSO receiver when they are operating in the same area but with randomized parameters. The output is I/N statistics at the FSS GSO receiver collected at each iteration of the Monte Carlo analysis. An AMS station is deployed as described below in Table 10-40 which contains the antenna gain, input power spectral density and bandwidth. The FSS earth station is assumed to be in Canada and sharing the same territory as the AMS terminal. Terrain data for this area in Canada was not included in the analysis. There are assumed to be GSO satellites spaced every 3 degrees and having receive coverage over the Canadian territory such that the minimum elevation angle of the FSS earth station of 10 degrees is respected.

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TABLE 10-40 Parameters considered in the study

Parameters Value Units FSS Earth station Latitude 50.63 ° North Longitude 96.5 ° West FSS GSO Noise Temperature 300 ° K Wanted Bandwidth 0.354 MHz G/T 17, 7 & –6 dB/K AMS ground station Tx On-axis Gain 44 dBi Power 1 dBW Interferer Bandwidth 0.354 MHz

Simulations were performed considering different AMS ground station positions relative to the FSS earth station. For each of these positions, One AMS aircraft at 19 km in altitude is assumed to have a random location within a circle of 577 km radius around the AMS ground station while an AMS aircraft station at 2.4 km in altitude is assumed to have a random location within a circle of 211 km radius. An aircraft altitude of 2.4 km and 19 km were both considered using the parameters of Airborne System 1 of Table 1 of the Annex. To simulate the position of the AMS aircraft, a Monte Carlo analysis was run for 10,000 iterations. The results show (see Table 10-41) likelihood of having of time when the I/N value at the FSS GSO receiver is lower than the FSS I/N protection criterion.

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TABLE 10-41 Percentage of time when I/N threshold is not exceeded

As can be seen in the above table, the percentage of potential interference impact from AMS into FSS GSO receiver is very limited under the simulated conditions.

10.2.3.3.3 Study #1A Summary for FSS (E-s) and AMS Sharing This study shows the total area where an AMS aircraft could be impacted by an FSS earth station located at different distance from the AMS ground station, assuming that the AMS ground station is fixed. This area ranges from 475 km² or 0.05% to 7 000 km² or 5.57% of the area considered in this study (see Fig. 10-27) when the FSS earth station is located at distance from 550 km, 1.10% at 400 km and 0.15% to 200 km with respect to the AMS ground station. The area around an AMS ground station within which the protection criterion is exceeded is non-uniform. Also note that the AMS ground station can be fixed or transportable. For transportable AMS ground stations, the shape and orientation variation of the non-uniform area has to be taken into account after relocating the AMS ground station itself. Most of the areas are located where the AMS aircraft sees the AMS ground station with a low elevation angle, less than 3° if the FSS earth station is located at 300 km from the AMS ground station, less than 1.5° at 400 km and less than 0.5° at 500 km. Depending of the terrain profile, the AMS ground station may or may not be able to see the AMS aircraft located at more than 500 km from the AMS ground station due to natural/house obstacles with such low elevation angles. This study also shows that the percentage of the potential interference impact from AMS into FSS GSO receiver is very limited (lower than 0.19% with a G/T of 17 dB/K and lower than 0.04 % with a G/T of 7 dB/K) considering configuration of the AMS aircraft and the AMS ground station considered in this study.

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10.2.3.4 Study #2 10.2.3.4.1 Study #2 Assumptions and methodology Study #2 considers the dynamic nature of the aeronautical mobile service and the FSS earth station transmissions. This considers the interference from a transmitting FSS earth station into receiving AMS terminals when they are operating in the same area but with randomized parameters. The output is I/N statistics at the AMS receiver collected at each iteration of the Monte Carlo analysis. A FSS earth station is deployed as described above in Table 8-32 which contains the antenna size, input power spectral density and bandwidth. The FSS earth station is assumed to be in Canada and sharing the same territory as the AMS terminal. Terrain data for this area in Canada was included in the analysis. There are assumed to be 40 GSO satellites spaced every 3 degrees and having receive coverage of the Canadian territory such that the minimum elevation angle of the FSS earth station is 10 degrees. This single FSS earth station using all of the bandwidth and transmitting 100% of the time and pointing towards one of the 40 GSO satellites at every time step of the simulation is assumed to be, for the purposes of this study, equivalent to multiple earth stations in the area transmitting to different satellites with a certain bandwidth and an inherent duty cycle depending on the type of transmission. The analysis does not account for simultaneous transmissions from different terminals in this same geographic area or from dispersion of terminals over the area of analysis. The analysis could take into account a more detailed deployment scenario for FSS earth stations in the area under analysis including VSATs, wideband and point-to-point earth station transmissions. In addition, further consideration could be given to defining the area around an earth station where the earth station causes interference above the protection criterion. For example, there could be multiple earth stations operating in this area, each transmitting to different satellites. These would result in different geometries and associated distribution of the interference area. However, there are mitigating factors that should be taken into fact, including: if a large number of VSAT terminals are modelled, their narrowband nature and time division access techniques should be taken into account. The AMS terminal parameters are shown in Table 8-34 above. One AMS terminal at 19 km in altitude is assumed to have a random location within a square that has an 870 × 870 km area (approximately) around the FSS earth station with random antenna pointing always toward the AMS ground station while an AMS terminal at 2.4 km in altitude is assumed to have a random location within a square that has a 320 × 320 km area (approximately). The aircraft altitude of 2.4 km and 19 km were both considered following the parameters of Airborne System 1 of Table 1 of the Annex to this Report. The square areas of 870 × 870 km and 320 × 320 km were chosen in consideration of the approximate radial line of sight distances associated with these airborne terminals. The results are displayed in I/N statistics collected at the AMS receiver based on the interference received from the FSS earth station at each interval of a Monte Carlo analysis. The Monte Carlo analysis was run for 10,000 iterations. The following table defines the random variables used in the analysis.

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TABLE 10-42 Random variable definition for parameters used in AMS Study #2

Random Variable Definition Distribution AMS aircraft latitude {19, 2.4} km altitude 50.63N ± {435, 160} km Uniform AMS aircraft longitude {19, 2.4} km altitude 96.32W ± {435, 160} km Uniform AMS ground station latitude {19, 2.4} km 50.63N ± {435, 160} km Uniform altitude AMS ground station longitude {19, 2.4} km 96.32W ± {435, 160} km Uniform altitude FSS earth station antenna pointing 1 of the 40 GSO satellites Uniform

It is noteworthy that in the simulation, the location of the FSS earth station remained constant in the center of the square box, i.e. constant at 50.63° N, 96.32° W.

10.2.3.4.2 Study #2 Analysis results The output of Study #2 is a plot of the I/N statistics at the AMS receiver collected at each iteration of the Monte Carlo analysis. The plot shown in Fig. 10-28 contains the I/N statistics at the AMS receiver when it is at 19 km or 2.4 km. Based on this analysis, the I/N criterion of –6 dB for the AMS receiver is exceeded. The criterion is to be met 100% of the time. From this plot, the AMS protection level of an I/N of –6 dB is met for 99.1% and 92.7% of the time for an AMS receiver at 19 km and 2.4 km an altitude respectively.

FIGURE 10-28 AMS receive I/N for a terminalAMS receive at 19 km link and I/N 2.4 statistics km in altitude above the terrain

100

10 AMS altitude of 19 km

0.1

Iterations (normalized %) Iterations (normalized

0.01 AMS altitude of 2.4 km

0.001

0 6

-6

-30 -24 -18 -12 I/N (dB)

10.2.3.5 Study #3 Previous studies have been focused on the compatibility between FSS earth stations with small antennas (VSATs) and stations in the AMS. This study considers earth stations with large antenna sizes, with a diameter of 6 m, typically used for wideband transmissions.

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This study is based on a model that simulates the potential harmful interference from an FSS earth station into an aeronautical mobile receiver in the 14.5-15.35 GHz band. The Interference-to-Noise ratio (I/N) and the separation distances to achieve a specific I/N are studied.

10.2.3.5.1 Study #3 Model & Assumptions An operational environment is set up with four stations: – Aircraft flying at a specific height; – Ground station for the aircraft; – FSS earth station on ground; – FSS geostationary satellite at a specific position. To simulate the operational environment, a 3-dimensional geographical area is defined where the stations are placed within the area. The AMS aircraft communicates with its associated ground station, always pointing towards the station. The FSS earth station communicates with its associated geostationary satellite with a fixed pointing towards the satellite. To determine the I/N at a specific distance, a grid is generated over the defined area where the earth station is placed at grid points within the area. At each grid point, the I/N at the AMS aircraft, as well as the corresponding interfering signal path length, is calculated as a snapshot in time. As a final step, an area where the I/N is met is identified and plotted across the defined area together with the interfering signal path length, in order to determine an approximate separation distance between the AMS aircraft and the FSS earth station. Aeronautical mobile service characteristics The AMS characteristics used is in this study are based on the data used in previous studies for subject frequency band (see § 10.2.3.2.2). System 1 (Airborne) in Table 1 of the Annex to this Report, is considered in this study.

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TABLE 10-43 Aeronautical mobile service characteristics Parameters used for AMS Value Units Notes aircraft parameter Frequency 14.6 GHz Assumed the same received frequency for all stations and transmitting frequency for all earth stations Bandwidth 10 MHz Document 5B/475 Aircraft height Minimum: 2.4; km From dish center to ground; Maximum: 19 Height above the terrain Maximum antenna gain 24 dBi Recommendation ITU-R M.1851 (uniform distribution) I/N permissible interference −6 dB Document 4A/147 level Noise figure 4 dB Document 4A/147 Probability of exceedence (p) 1 % Using Rec. ITU-R P.528-3 propagation model, due to weather statistics no terrain or obstacles

FSS earth station characteristics The FSS earth station characteristics used in this study are a combination of the values considered in § 4 of this Report and at five different positions from the AP30A Plan/List. The studied cases are summarized in Table 10-44.

TABLE 10-44 Earth Station characteristics

Case study A B C D E GSO position [°E] –37 –1 5 38.2 108.2 Satellite name SEN22201 MOZ30701 SIRIUS-5E- PAK12701 NSS-BSS BSS 108.2E Owner SEN MOZ S PAK HOL ITU status Plan Plan List Plan Pending Earth station antenna size 6 [m] Earth station antenna pattern Recommendation ITU-R S.580-6 Input power density –49.3 –49.3 –57 –49.3 –57 [dBW/Hz] Geographical area Senegal Mozambique South Africa Pakistan India

10.2.3.5.2 Study #3 Results In the Figures below, the contour in red defines the area where the I/N criteria of ‒6 dB is met. The circular contours around the aircraft are representing different distances from the aircraft which correspond to the interfering signal path length.

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10.2.3.5.2.1 Case A The results when an earth station is operating as defined in Case A, and interferes with an AMS aircraft operating at an altitude of 2.4 km is presented in Fig. 10-29 below. The 19 km case is shown in Fig. 10-30. A separation distance for the 2.4 km case is estimated to be 150 km, and for the 19 km case is slightly below 500 km.

FIGURE 10-29 Case A with AMS aircraft at 2.4 km altitude

FIGURE 10-30 Case A with AMS aircraft at 19 km altitude

10.2.3.5.2.2 Case B The results when an earth station is operating as defined in Case B, interfering with AMS aircrafts operating at an altitude of 2.4 km and 19 km is presented in Fig. 10-31 below. A separation distance for the 2.4 km case is estimated to be 150 km, and for the 19 km case 400 km. Rep. ITU-R S.2365-0 275

FIGURE 10-31 Case B vs AMS aircrafts at 2.4 km and 19 km altitudes

10.2.3.4.2.3 Case C The results when an earth station is operating as defined in Case C, interfering with AMS aircrafts operating at an altitude of 2.4 km and 19 km is presented in Fig. 10-32 below. A separation distance for the 2.4 km case is estimated to be 150 km, and for the 19 km case is slightly below 500 km.

FIGURE 10-32 Case C vs AMS aircrafts at 2.4 km and 19 km altitudes

10.2.3.4.2.4 Case D The results when an earth station is operating as defined in Case D, interfering with AMS aircrafts operating at an altitude of 2.4 km and 19 km is presented in Fig. 10-33 below. A separation distance for the 2.4 km case is estimated to be 150 km, and for the 19 km case is slightly below 500 km.

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FIGURE 10-33 Case D vs AMS aircrafts at 2.4 km and 19 km altitudes

10.2.3.4.2.5 Case E The results when an earth station is operating as defined in Case E, interfering with AMS aircrafts operating at an altitude of 2.4 km and 19 km is presented in Fig. 10-34 below. A separation distance for the 2.4 km case is estimated to be 150 km, and for the 19 km case 400 km.

FIGURE 10-34 Case E vs AMS aircrafts at 2.4 km and 19 km altitudes

A summary of the estimated max separation distances identified in the 5 cases considered in this study is found in Table 10-45.

TABLE 10-45 Summary of results

Case study A B C D E Distance for 2.4 km AMS [km] 150 150 150 150 150 Distance for 19 km AMS [km] 500 500 400 500 400

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10.2.3.4.3 Study #3 Summary Based on the assumptions in this study, it has been shown that, in order to respect the I/N −6 dB protection criteria, the separation distance between a transmitting FSS earth station and a receiving AMS aircraft is 150 km for an aircraft flying at an altitude of 2.4 km, and 400-500 km for an aircraft flying at an altitude of 19 km, depending on the power density input to the FSS earth station. For the latter case (19 km), a power density of –57 dBW/Hz results in a separation distance of 400 km, and a power density of –49.3 dBW/Hz results in a separation distance of 500 km. The separation distances define an area around the AMS where the I/N criteria is exceeded, when the AMS system moves, so does the associated area. Additionally, it is worth noting that results calculated in this study (performed using parameters in AP30A (see Table 10-44 above)) are comparable with those of other studies in regards to FSS into AMS

10.2.3.6 Study #4 This study #4 specifically considers the time variant nature of the AMS stations and the FSS (Earth-to-space) transmissions in order to evaluate the impact of the interference when the FSS earth station is systematically moved at particular distances away from the AMS ground station. The objective this study is to statistically show that the I/N = –6 dB protection criterion can be met for the AMS system, when a certain (given) minimum separation distance is maintained between the AMS ground station and the FSS earth station location.

10.2.3.6.1 Study #4 Methodology and Assumptions The initial part of the study #4 relies on the following assumptions related to the AMS architecture: • A single AMS ground station fixed at a given Lat/Lon (Lat: 50.63, Long: –96.50) for each different simulation within a 211 and 577 km radius from the AMS ground station (for 2.4 and 19 km AMS altitude respectively) and takes into account local terrain • AMS carrier assumed to have same bandwidth as FSS carrier (i.e. 36 MHz) • AMS protection criterion is an I/N of −6 dB for all conditions • AMS aircraft station randomly positioned (Lat/Lon) around AMS ground station and having an altitude of either 2.4 or 19 km. • The gain of actual AMS aircraft and ground station antenna was used, however the values were not available The following assumptions were made related to the FSS architecture: • FSS earth station, at fixed known locations, with diameters: 1.2, 2.4 and 6 m but systematically moved with respect to the AMS ground station location. • FSS input power density (constant for all antennas): −50 dBW/Hz • Recommendation ITU-R S.465 used for antenna pattern for off-axis • 52 FSS GSO satellites located on the 20 W to 173 W arc (with a 3 degree spacing) • FSS earth station randomly point to one visible satellite (out of the 52 satellites) at each iteration (with a minimum elevation angle of 10°) • Free space propagation model was used including terrain profile for this specific location. A variety of geometrical configurations are considered, in order to find preliminary correlation patterns between the required I/N factor and the distance between the AMS ground station and the FSS earth station (the latter being fixed in a different location for each simulation case), as well as preliminary correlation patterns between the desired I/N factor and the angular directional

278 Rep. ITU-R S.2365-0 displacement (i.e. North, South, East, and West directional offset) of the FSS earth station with respect to the AMS ground station.

TABLE 10-46 FSS ground stations offset with respect to AMS ground stations in the different cases

FSS earth station AMS ground station FSS earth station location offset relative to Area of location AMS ground interest station Lat Lon Case # Lat Lon 20 km N 1 50.81 –96.50 20 km S High 2 50.45 –96.50 50.63 –96.50 20 km E latitude 3 50.63 –96.216 20 km W 4 50.63 –96.784 50 km N 5 51.08 –96.50 50 km S High 6 50.18 –96.50 50.63 –96.50 50 km E latitude 7 50.63 –95.79 50 km W 8 50.63 –97.21 100 km N 9 51.53 –96.50 100 km S High 10 49.73 –96.50 50.63 –96.50 100 km E latitude 11 50.63 –95.08 100 km W 12 50.63 –97.92 250 km N 13 52.88 –96.50 250 km S High 14 48.38 –96.50 50.63 –96.50 250 km E latitude 15 50.63 –93.03 250 km W 16 50.63 –99.97

Individual 10,000-iteration Monte Carlo simulations were built for each of the above listed system configurations. The second part of this study #4 is based builds on the results of the first part and utilizes a more generic approach, in order to evaluate the statistical correlation between the baseline distance between the FSS earth station and the AMS ground station in the most comprehensive fashion, by averaging the effect of the directional position of the FSS earth station with respect to the AMS ground station. Hence, instead of placing the FSS earth station in a predefined location (i.e. 100 km N, S, E, or W with respect to the AMS ground station) for the whole duration of each simulation (10,000 iterations), it was decided to consider the latitude and longitude of the FSS earth station as two additional variable parameters for the Monte Carlo analysis. This approach, by coupling the impact of continuously variable latitude and longitude, allowed studying the I/N ratio on a circumference with predefined radius. Three simulations were performed with the different values for the radius, leading to the following cases: Case 17: − FSS earth station randomly placed at 50 km baseline distance from the AMS ground station, with FSS earth station’s latitude and longitude forced to change at each iterations but constrained on the 50 km radius circumference; Rep. ITU-R S.2365-0 279

Case 18: − FSS earth station randomly placed at 100 km baseline distance from the AMS ground station, with FSS earth station’s latitude and longitude forced to change at each iterations but constrained on the 100 km radius circumference; Case 19: − FSS earth station randomly placed at 250 km baseline distance from the AMS ground station, with FSS earth station’s latitude and longitude forced to change at each iterations but constrained on the 250 km radius circumference.

10.2.3.6.2 Study #4 Results The output of each case considered in the first part of is a statistical I/N plot of a given AMS aircraft station receiver, experiencing interference from 10,000 samples of a single FSS uplink transmission. The plot directly shows the percentage of instances when the I/N ratio is within the limit of the protection criterion (i.e. I/N at –6 dB). Table 10-47 presents the results.

TABLE 10-47 Percentage of instances with I/N within protection criterion limit

FSS earth station offset Percentage of instances with I/N within Case # relative to AMS ground protection criterion limit station AMS 2.4 km AMS 19 km 1 20 km N 5.9% 50.2% 2 20 km S 6.0% 50.0% 3 20 km E 6.5% 51.0% 4 20 km W 6.4% 50.4% 5 50 km N 62.0% 74.2% 6 50 km S 65.1% 76.3% 7 50 km E 62.6% 75.0% 8 50 km W 63.0% 75.9% 9 100 km N 82.1% 87.0% 10 100 km S 84.1% 86.5% 11 100 km E 84.0% 88.8% 12 100 km W 86.1% 91.3% 13 250 km N 99.1% 96.3% 14 250 km S 99.9% 96.5% 15 250 km E 99.9% 96.9% 16 250 km W 99.9% 96.6%

The first relevant point to notice is the fact that an AMS airborne station flying at an altitude of 19 km shows a greater percentage of instances with I/N below protection criterion limit than an AMS airborne station flying at an altitude of 2.4 km when the FSS earth station and the AMS ground station are separated by a 20, 50, and 100 km distance. The same does not apply when the 250 km separation distance is considered and the reason is that the when the distance increases, the overlapping area between the FSS earth station-to-satellite beams and the AMS mobile-to-AMS ground station beams increases (due to geometrical reasons) for higher altitude AMS. This results in a greater probability

280 Rep. ITU-R S.2365-0 of having the FSS earth station interfering with the AMS flying at 19 km than with the AMS flying at 2.4 km and results in a higher overall percent value for the lower altitude AMS. By analysing the output values of cases 1, 2, 4, 5, 9, 10, 13, 14 that the configurations where the FSS earth station is located to the north of the AMS ground station are worse (meaning that they result in a lower percentage) that those cases where the FSS earth station is placed to the south. This expected result is due to the fact that the analysed area is at high latitude, hence the likelihood of the FSS earth station (which is always pointing southwards to GSO satellites) interfering with the AMS transmissions is greater when the AMS ground station is at a lower latitude than the FSS earth station. Unlike the North and South cases, it is reasonable to think that the East and West cases should show the same results being the configuration solely dependent upon the longitude value and being it symmetric with respect to the AMS ground station location. However, by analysing the output values of cases 3, 4, 7, 8, 11, 12, 15, 16 one should notice that the results for each given distance are not the same in case of East and West configuration. This is clearly due to the impact of the terrain profile in the simulation and shows the importance of including the terrain in such a type of studies. The impact of the terrain on the overall output is the rationale behind the following part of this study. In fact, in order to include the terrain but still be able to randomize the AMS/FSS configuration and extract statistical results, it is necessary to consider not only the North, South, East, or West position of the FSS earth station, but the totality of the Lat, Lon pairs whose combination generates the circumference of given radius. Building on the above reported cases from 1 to 16, the following radii were chosen: 50 km, 100 km, and 250 km; those radii respectively correspond to cases 17, 18, and 19 hereby reported: Case 17

FIGURE 10-35 FSS earth station randomly positioned at 50 km (red contour) from the AMS ground station

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FIGURE 10-36 AMS aircraft I/N at 2.4 and 19 km altitude interference from a single FSS earth station (various antenna diameters) positionsAMS at receive 50 km radius link I/Nfrom statistics AMS ground station

100

AMS 19km - 1.2m FSS

AMS 2.4km - 1.2m FSS

1 AMS 19km - 2.4m FSS

0.1 AMS 2.4km - 2.4m FSS

0.01 AMS 19km - 6m FSS

I/N level - probability of occurrence (%) I/Nof - probability occurrence level

AMS 2.4km - 6m FSS 0.001

0 6

-6

-30 -24 -18 -12 I/N (dB)

The probability of exceeding the protection criterion is 36.5%for an aircraft flying at an altitude of 2.4 km and of 26% probability for an aircraft flying at an altitude of 19 km. Case 18

FIGURE 10-37 FSS earth station was randomly positioned at 100 km (red contour) at 100 km (red contour) from the AMS ground station

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FIGURE 10-38 AMS aircraft receive I/N at 2.4 and 19 km altitude interference from a single FSS earth station (various antenna diameters) positionedAMS receive at 100 km link from I/N statisticsAMS ground station

100

AMS 19km - 1.2m FSS

AMS 2.4km - 1.2m FSS

1 AMS 19km - 2.4m FSS

0.1 AMS 2.4km - 2.4m FSS

0.01 AMS 19km - 6m FSS

I/N level - probability of occurrence (%) I/Nof - probability occurrence level

AMS 2.4km - 6m FSS 0.001

0 6

-6

-30 -24 -18 -12

I/N (dB) The probability of exceeding the protection criterion 15.5% probability of having I/N within protection criterion limit for an aircraft flying at an altitude of 2.4 km and of 11.7% for an aircraft flying at an altitude of 19 km. Case 19

FIGURE 10-39 2 FSS earth station was randomly positioned at 250 km (red contour) from the around AMS ground station

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FIGURE 10-40 AMS aircraft I/N at 2.4 and 19 km. Interference from a single altitude from various FSS earth station (various antenna diameters)AMS receive positioned link I/Nat 250 statistics km from the AMS ground station

100

AMS 19km - 1.2m FSS

AMS 2.4km - 1.2m FSS

1 AMS 19km - 2.4m FSS

0.1 AMS 2.4km - 2.4m FSS

0.01 AMS 19km - 6m FSS

I/N level - probability of occurrence (%) I/Nof - probability occurrence level

AMS 2.4km - 6m FSS 0.001

0 6

-6

-30 -24 -18 -12 I/N (dB)

The probability of exceeding the protection criterion is 0.23% for an aircraft flying at an altitude of 2.4 km and of 3.1% probability for an aircraft flying at an altitude of 19 km. The 19 cases analysed above resulted in outputs which are independent from the antenna size; in fact cases from 1 to 16 are solely dependent on the AMS aircraft flight altitude, on the northern, southern, eastern, or western FSS earth station to AMS ground station directional offset, and on the terrain profile, while cases from 17 to 19 are solely dependent on the AMS aircraft flight altitude, terrain profile, and on the distance between the FSS earth station and the AMS ground stations.

10.2.3.6.3 Study #4 Summary The study considers 19 different cases in which the FSS earth station position is changed with respect to the AMS ground station in order to define the relation of such position with the I/N ratio obtained at the AMS aircraft receiver. The analysis was done for two AMS aircraft flight altitudes. On this purpose, cases 1 to 16 are aimed at analysing the statistical correlation between the FSS earth station position (northern, southern, eastern, or western) and distance with respect to the AMS ground station The terrain profile was taken into account. Cases from 17 to 19 aimed to analyse the statistical correlation between the aircraft station flight altitude and the distance (circular) between the FSS earth station and the AMS ground stations. The 19 cases considered were performed for a single and fixed AMS ground station location, considering the terrain profile. The most relevant results of the study for the scenario and assumptions considered are that: − the exceedance of the AMS protection criterion (I/N = −6 dB) is independent from FSS earth station the antenna size; − for the AMS station location considered in this study and taking into account the local terrain, it was found that the interference from the FSS earth station to a low altitude AMS aircraft station is greater than the one for a high altitude AMS aircraft station and the FSS earth station when the distance between the FSS earth station and the AMS ground station is . below 250 km. The opposite is true when the distance is greater than 250 km; − the terrain plays a significant role in the results for the study of interference;

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− the location of the FSS earth station and AMS ground station as well as the terrain model condition the results of the interference assessment (i.e. as the latitude increases, North or South, the FSS elevation angle decreases and is likely to overlap with AMS beam more frequently)

10.2.3.7 Study #4A 10.2.3.7.1 Relationship between AMS aircraft station altitude and FSS earth station distance from AMS ground station Study #4A is based on the findings of Study #4 in order to expand on the analysis and to get more detailed results. A number of Monte Carlo simulations were performed and the most representative are hereby described. As first step, the following parameters were considered: fixed AMS ground station at equatorial latitude in a rural area where the terrain was mostly flat, variable AMS aircraft station flight altitude anywhere between zero and 19 km above the terrain, and FSS earth station placed randomly within a 500 km radius from the AMS ground station. Free space propagation model was used including terrain profile for this specific location. It was considered the communication of the AMS ground station and the airborne station is limited to the field of view. The Monte Carlo simulation performs 100,000 iteration (as opposed to the 10,000 of Study #4), due to the much greater extension of the considered volume. All other parameters are the same as in Study #4. The AMS station antenna pattern is not provided In order to evaluate the results, only those instances corresponding to I/N > –6 dB where considered and the aircraft station altitudes were plotted as function of FSS radial distance from the AMS ground station. The resulting diagram follows.

FIGURE 10-41 AMS aircraft I/N > −6 dB as a function of FSS earth station distance from AMS ground station (km)

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The blue line in the diagram represents the upper bound of the 100% accepted area and that the term “accepted” should be intended as “number of instances meeting the protection criterion”. In order to clearly understand the above graph one should note that its shape represents a 2D view of the irregular hemisphere (whose irregularities are due to the inclusion of terrain in the analysis) that would result in forcing the graph to revolve around the y-axis (namely, the AMS aircraft station flight altitude axis). In addition the density of points is the result of the collapse the 3D irregular hemispheric volume into a 2D semi-plane which has its origin coincident with the 2D upper bound curve (or, in 3D, the upper bound surface) of the 100% accepted I/N area (i.e. the blue line in the above graph). For the sake of clarity, a 3D representation of the 100% accepted I/N upper bound surface is reported, also including the instances for which the I/N protection threshold is exceeded (blue dots in the following graph):

FIGURE 10-42 3-dimensional view of AMS I/N >-6 as a function of AMS aircraft station altitude and FSS earth station distance from AMS ground station with solid surface showing the 100% I/N < −6 dB

500 10 400

8 300

200 6 100

4 0

Volume outside the 3D -100 2 cone: the I/N -200 0 -300

AMS flight altitude (km) protection criteria is -400 500 400 300 200 100 0 always met -500 -100 -200 -300 -400 FSS earth station distance from AMS ground station (km) -500

Relevance of the graph is to show the existence of a volume (being it the one outside the multi- coloured surface) where the considered AMS system could share with an FSS earth station transmitting in the same frequency band. Under the considered scenario, the I/N protection criterion is not exceeded for an AMS aircraft station flying at any altitude when an FSS earth station is located at a minimum distance of 482.39 km from the AMS ground station. Said distance can be reduced for AMS aircraft stations flying at altitudes below 17,264 m (i.e. in the case of an AMS aircraft altitude of 4 km, the minimum distance for an FSS earth station would be 245.0 km, in order to ensure a 100% operational availability).

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The following plot shows the FSS earth stations surface location (in red) together with the AMS aircraft station positions (in blue). Recall that for this analysis, an FSS earth station was considered per iteration.

FIGURE 10-43 Blue points are the AMS aircraft station coordinates (lat, lon, altitude) where I/N > −6 dB and red points are the FSS earth station coordinates that caused the AMS aircraft I/N to exceed −6 dB

4 x 10

1.8

1.6

1.4

1.2

0.8

0.6

0.4

0.2

0 1000

500

-500 600 200 400 -1000 -200 0 -600 -400

The aim is again to highlight the huge volume where an FSS earth stations and AMS aircraft station could operate without exceeding the I/N protection criterion, under the assumptions and scenario considered. As second step, it is possible evaluate what is the percentage of exceeding I/N per different FSS earth station radius ranges. The percentage of instances when the protection criterion is not met for the particular AMS ground station position and characteristics is shown on the following bar diagram: Rep. ITU-R S.2365-0 287

FIGURE 10-44 AMS aircraft I/N statistics as a function of FSS earth station distances from the AMS ground station considered. The blue line indicates the distance the likelihood of having I/N < −6 dB is at least 99%

The above graph shows that the probability of having I/N > –6 dB among the totality of results of the Monte Carlo simulation (initially very high when the FSS earth station is within 20 km from the AMS ground station) decreases drastically, eventually reaching stability below the 0.8% when the FSS earth station is located at 340 km minimum distance from the AMS ground station. The reason why the percentage numbers do not seem to follow the progression of the red bar size (e.g. at 60 km the red bar is taller than the one at 40 km, but the corresponding percentage is lower: 10.9% and 15.4% respectively). This behaviour is due to the fact that, while the length of the red bar is based on the numbers of instance with unacceptable I/N ratios, the percentage values are calculated by evaluating the unacceptable I/N versus the totality of I/N instances for each particular FSS radius range; hence it is normal to see a decreasing percentage corresponding to a greater FSS radius range because of the larger number of I/N accepted instances occurring at greater radii. As a further step, one could perform a sensitivity analysis on Fig. 8-41 in order to evaluate the gain in terms of FSS earth station proximity to the AMS ground station with respect to the number of instances not meeting the protection criterion. The results are shown in Fig. 10-45 below.

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FIGURE 10-45 I/N results at the AMS aircraft station for different altitudes and distance between AMS ground station and an FSS earth station

19000 18000 17000 16000 15000 14000 13000 12000 11000 10000 95% AMS I/N > -6 9000 98% AMS I/N > -6 8000 7000 100% AMS I/N > -6 AMS AMS flight altitudein m 6000 5000 100% Accepted I/N Area at 95% instances 4000 3000 100% Accepted I/N Area at 98% instances 2000 1000 100% Accepted I/N Area at 100% instances 0 0 100 200 300 400 500 FSS Ground Station baseline from AMS Ground Station in km

The above graph shows that the baseline radius of the “100% accepted I/N area” when considering the totality of instances with I/N exceeding the protection criterion (whose worst case extends to up to 482.39 km from the AMS ground station) is not linearly proportional to the number of instances. In fact, when considering the 98% of unacceptable instances, the “100% accepted I/N area” grows of a much greater percentage than 2%. When considering the 95% of unacceptable instances, the “100% accepted I/N area” grows by nearly 40%. The sensitivity analysis was based on a point density analysis, centred in the “center of mass” of the plot, located within the first 40 km from the AMS ground station and ideally located right on top of it at the maximum considered altitude (the latter being 19 km for the present study)

10.2.3.7.2 Study #4A Summary Study #4A is aimed at finding statistical results that can be used to draw conclusions on the FSS-to- AMS interference issue. Results of this study are that: − the minimum distance between the AMS ground station and the FSS earth station cannot be computed in a two dimensional space, without losing crucial information and cannot be assumed to be constant (e.g. it is not correct to say that the minimum baseline distance should be 500 km for all configurations; on the contrary, it is correct to say that the minimum baseline distance between an AMS ground station located at equatorial latitude (flat and rural terrain) and an FSS earth station with the characteristics considered in this study, should be 245 km for an airborne AMS aircraft station flying at an altitude of 4 km above the terrain level); Rep. ITU-R S.2365-0 289

− across the whole examined volume, and for the assumptions considered in this study, the number of instances causing an I/N ratio exceeding the protection criterion is 839 out of 50,969, which is 1.646%; − beyond 340 km separation distance between the AMS ground station and FSS earth station, the likelihood of having an I/N exceeding the protection criterion by an FSS earth station is less than or equal to 0.8%; − for each FSS radius around an FSS earth station, it is always possible to find an operational volume where the I/N ratio at the AMS aircraft does not exceed the protection criterion and, consequently, a volume in which it is exceeded.

10.2.3.8 Study #5 Study #5 expands upon previous studies #1 to #4a to assess the sharing and compatibility between FSS earth stations and AMS aircraft station due to the fact that: – the AMS aircraft station has potentially ubiquitous positions; – analysis is expanded to “system 6” of Table 1 of the Annex to this Report – the air-to-air AMS communication scenario is taken into account. In such a scenario, the position of the AMS ground station has no influence on the results. This study interference assessment used the following ITU-R Recommendations as they were developed for such purpose: • Recommendation ITU-R S.465-6 ‒ Reference radiation pattern of earth station antennas in the fixed-satellite service for use in coordination and interference assessment in the frequency range from 2 to 31 GHz. • Recommendation ITU-R S.1855 ‒ Alternative reference radiation pattern for earth station antennas used with satellites in the geostationary-satellite orbit for use in coordination and/or interference assessment in the frequency range from 2 to 31 GHz. Additionally this study considers two types of FSS earth stations (implementing 2.4 m and 6 m antenna diameter). Simulations were conducted for distances between AMS aircraft station and FSS earth station up to 450 km and for aircraft altitudes from 1 000 to 20 000 m.

10.2.3.8.1 FSS (E-s) parameters The FSS earth station parameters used for the study are provided in Table 10-48.

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TABLE 10-48 Parameters used for the FSS in Study 5

2.4 antenna 6 m antenna Parameter diameter diameter Frequency GHz 14.7 14.7

Antenna elevation angle (θt) Deg 10 10 Antenna diameter m 2.4 6 Antenna height above the terrain m 10 10

Antenna gain pattern (GT) Rec. ITU-R S.1855 Rec. ITU-R S.465-6

Antenna peak gain (G0t) dBi 49.4 57.4 Variable (depending Variable (depending Antenna gain towards AMS dBi of the aircraft of the aircraft aircraft (G ) FSS,Tx position) position) FSS Transmit PSD dBW/Hz −49 −49

10.2.3.8.2 AMS parameters The AMS aircraft station parameters that are used for the study are provided in Table 10-49. They are extracted from Table 1 of the Annex to this Report.

TABLE 10-49 Parameters of system 6 used for the AMS airborne receiving station in the study

System 6 Parameter Units airborne/ground/ shipboard terminals Receiver Tuning range GHz 14.5 – 15.35 3 dB MHz 120 RF selectivity 20 dB MHz NAvail1 60 dB MHz NAvail1 3 dB MHz 0.85 to 120 IF selectivity 20 dB MHz NAvail1 60 dB MHz NAvail1 NF dB 3.5 Sensitivity dBm −110 Image rejection (dB) 60 Spurious rejection (dB) 65 Antenna

Antenna gain (GAMS,Rx) dBi 3 Antenna pattern/type Omnidirectional (1): NAvail – Not Available

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10.2.3.8.3 Propagation model

Recommendation ITU-R P.528-3 has been used to assess the transmission losses (PL) from the FSS earth station transmitter to the AMS aircraft station receiver. The curves given in Annex 3 of Recommendation ITU-R P.528-3 have been adopted to determine the transmission losses for 1% transmission losses availability. This percentage corresponds to the percentage considered in studies #1 to #4/4A. The AMS protection criterion is (I/N < −6 dB), no percentage of time is specified in Table 1 of the Annex of this Report. In this study, the minimum aircraft altitude has been set to 1 000 m.

10.2.3.8.4 Configuration and methodology This study examines the potential interference from an earth station operating in the FSS into an AMS aircraft station and assesses the probability of exceeding the protection criterion on the AMS aircraft receiver. Only one interfering FSS earth station is used, so the study performed is a single entry analysis with a Monte-Carlo methodology to assess the interference probability. Depending on the deployment density of the FSS transmitting earth stations, the aggregate effect of their emissions may generate interference levels higher than what is calculated in this study. The FSS transmitting earth station is pointing towards one FSS GSO satellite. The AMS aircraft receiving station antenna is omnidirectional, so no particular direction of pointing of the AMS antenna receiver is considered. In consequence, the position of the associated AMS ground station has no effect on the assessment of interference. Thus, in this configuration the I/N value is only related to the respective position of the AMS aircraft and the FSS earth station (direction of arrival of the interfering signal). The AMS receiving aircraft station protection criterion of I/N < −6 dB used in this analysis is given in Table 1 of the Annex of this Report. Since there is no percentage of time explicitly associated to this criterion, a part of the community considers that it should be fulfilled 100% of time. The corresponding interference scenario is shown in Fig. 10-46.

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FIGURE 10-46 Interference scenario

The Monte Carlo study considered random AMS aircraft distances (in the range 0 to 450 km), random AMS aircraft altitudes (in the range 1 000 to 20 000 m) and random AMS aircraft azimuth (over 360°) when computing the probability of interferences. The study considered 200,000 iterations. The interference from an FSS transmitting earth station into the AMS receiving aircraft station normally arises under radio-line of sight (LOS) propagation conditions but can also occur beyond LOS conditions. A central frequency of 14.7 GHz was assumed. The FSS earth station antenna is assumed to be mounted at a typical level of 10 m. The level of the FSS earth station interference (I in dBW) at the AMS aircraft receiver input (considered in the AMS receiver bandwidth) is given by:  = FSS transmit PSD  G  P  10 log BW  G FSS,Tx L AMS,Rx AMS,Rx with: • FSS transmit PSD in dBW/Hz;

• FSS earth station transmitter antenna gain in the direction of the AMS aircraft station GFSS,Tx in dBi;

• Path loss PL in dB;

• 3 dB AMS receiver bandwidth BWAMS,Rx in Hz;

• AMS aircraft receiver antenna gain in the direction of the FSS earth station GAMS,Rx in dBi. It should be noted that the results remain valid for all cases of AMS receiver bandwidth characteristics that are equal or lower than the FSS transmitter bandwidth. Rep. ITU-R S.2365-0 293

10.2.3.8.5 Results of the study Two types of FSS earth stations have been selected; one with an antenna diameter of 2.4 m and one with an antenna diameter of 6 m. The characteristics of system 6 are used in the study to be representative of the AMS air-to-air communication case. Two configurations are studied: – An FSS earth station with antenna diameter of 2.4 m and the AMS System 6. – An FSS earth station with antenna diameter of 6 m and the AMS System 6. For each of the two configurations, in order to assess the exceedance of the I/N protection criterion from the FSS earth station towards the AMS aircraft receiver, dynamic analyses have been done to consider the dynamic nature of the aeronautical mobile service. Random variables have been used to set the aircraft distance and altitude with respect to the FSS earth station. The results provide I/N statistics at the AMS aircraft receiver computed from each iteration of the Monte Carlo analysis. The relative position of the AMS aircraft from the FSS earth station is determined by the two following parameters: – Distance between the FSS earth station and the AMS aircraft station (see AMS aircraft distance in italic inside Fig. 10-46). – Altitude of the AMS aircraft station (see AMS aircraft altitude in italic inside Fig. 10-46). – The azimuth of the AMS aircraft station with respect to the FSS earth station The results of the study are presented in Tables 10-51 and 10-52. These tables present the probability of exceeding the I/N protection criterion as a function of the distance and the altitude range of the AMS aircraft from the FSS earth station. Due to the fact that the aircraft position is uniformly distributed in the simulation volume, this probability of interference exceeding the protection criterion corresponds to the percentage of the total considered volume (defined by the distance and altitude range) where the I/N criterion is exceeded. Three operational scenarios have been studied. These scenarios correspond to some typical operational usage of AMS data links: – Scenario 1: corresponding to the overall range of aircraft altitude (1 000 m to 20 000 m) and within the distance range from 0 to 450 km. – Scenario 2: corresponding to an aircraft ensuring typical missions such as remote sensing, forest fire mapping, natural resource surveys, border surveillance. In that case the range of altitude is 7 600 m to 13 700 m (25 000 ft to 45 000 ft) with distance range from 0 to 450 km. – Scenario 3: corresponding to a smaller aircraft or helicopter ensuring the same typical missions as for scenario 2. In that case the range of altitude is 1 000 m to 4 570 m (15 000 ft) with distance range from 0 to 200 km. In addition, in order to provide comparable results with other studies, several separation distances have been calculated. Table 10-52 provides the separation distances between the AMS aircraft station and the FSS earth station for two aircraft altitudes 2 400 and 19 000 m. Two cases have been studied corresponding to two different scenarios: AMS aircraft station within the FSS earth station mainlobe azimuth or outside the FSS earth station mainlobe azimuth.

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TABLE 10-50 Interference probability from a 2.4 m FSS earth station antenna diameter for the three AMS scenario

Probability AMS aircraft of exceeding AMS aircraft distance from FSS the I/N altitude Scenarios earth station protection criterion Min Max Min Max % (m) (m) (km) (km) 1 000 20 000 0 450 8.96 Scenario 1 1 000 20 000 0 200 30.06 7 620 13 710 0 450 9.33 Scenario 2 7 620 13 710 0 200 32.11 1 000 4 572 0 450 4.75 Scenario 3 1 000 4 572 0 200 24.13 1 000 4 572 0 100 76.55

TABLE 10-51 Interference probability from a 6 m FSS earth station antenna diameter for the three AMS scenario

Probability AMS aircraft AMS aircraft of exceeding distance from FSS altitude I/N protection earth station Scenarios criterion Min Max Min Max % (m) (m) (km) (km) 1 000 20 000 0 450 9.33 Scenario 1 1 000 20 000 0 200 30.3 7 620 13 710 0 450 10.4 Scenario 2 7 620 13 710 0 200 31.96 1 000 4 572 0 450 4.76 Scenario 3 1 000 4 572 0 200 23.99 1 000 4 572 0 100 76.38

Rep. ITU-R S.2365-0 295

TABLE 10-52 Separation distances for minimum and maximum interferences scenario, 6 m FSS antenna diameter

AMS aircraft separation AMS aircraft separation AMS aircraft distance from FSS distance from FSS earth station, altitude earth station, AMS aircraft AMS aircraft outside the FSS in the FSS main beam azimuth main beam azimuth 2 400 m 151 km 83 km 19 000 m 451 km 87 km

10.2.3.8.6 Summary of study #5 Simulations have been conducted for distances between AMS aircraft station and FSS earth station up to 450 km and for aircraft altitudes from 1 000 to 20 000 m for three operational scenarios. The dynamic Monte Carlo analysis for 2.4 m and 6 m antenna diameter FSS earth stations shows that a significant probability of exceeding the protection criterion for separation distances up to 450 km. Probabilities can reach 10% in case of AMS aircraft-FSS earth station separation distance in the range of 0 to 450 km and between 24% and 32% in case of AMS aircraft-FSS earth station separation distance in the range of 0 to 200 km. For the system considered, there is no influence of the AMS ground station position. The closer the distance between the AMS aircraft station and the FSS earth station, the higher the likelihood of harmful interference into the AMS aircraft station, i.e. for example 100% below 83 km distance for an AMS aircraft operating at an altitude of 2400 m. To avoid exceeding the protection criterion, separation distances up to 450 km are required to protect the AMS.

10.2.3.9 Study #6 AMS systems operating in both the bands 14.5-14.8 GHz and 14.8-15.35 GHz are often correlated with governmental aerial surveillance operations aimed at monitoring refugees migration, preventing smuggling, traffic of weapons, etc., as well as monitoring public order and safety during major events or natural disasters, and safeguarding national/international security. Operations may be carried on by piloted aircraft, as well as Unmanned Aircraft Systems (UAS), now internationally renamed as Remotely Piloted Aerial Systems (RPAS). This study expands upon studies #1, #1A, #2, #3, #4, #4A, and #5 and takes into account, in particular, the correlation between the geographical extension of the interference area generated by FSS earth station and the time required to cross it at typical aircraft speed during surveillance operations. Study #6 is aimed at closing this gap, providing some quantitative evaluations of the impacts of FSS earth station interference on the AMS service continuity. Considering the typical aircraft speed during surveillance operations, when the AMS airborne station enters the FSS interference zone and the AMS link interruption is likely to occur, the link loss period is long enough to determine a total loss of tracking by the AMS ground station. In such case, a complete link recovery procedure must be initiated. In these conditions, a service interruption from several tens of seconds to several minutes can be predicted (depending from the speed and the trajectory of the aircraft).

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10.2.3.9.1 Operational scenarios Two possible realistic scenarios have been considered within the present analysis: – a Coastal scenario, where an aircraft/RPAS hosting the AMS airborne station (ADT) is supposed to execute a patrolling mission south of Sicily island to monitor refugees migration. The AMS earth station (GDT) is deployed in the western part of Sicily. – Two FSS earth stations (FSS1 and FSS2) with 2.4 m antenna diameter (VSAT) are assumed to be located along the southern coast of Sicily and pointed towards an existing GSO satellite with Ku-band coverage over the area (Intelsat IS-903 at 34.5 W longitude): indeed, though this satellite does not operate yet in 14.5-14.8 GHz and 14.8-15.35 GHz band, it provides a good example of a “would-be” situation in the case of spectrum sharing between FSS and AMS. – an Inland scenario, where an aircraft/RPAS hosting the AMS airborne station (ADT) is supposed to execute a mission over the Sicily territory to detect wild fires or provide aerial surveillance in case of major events, natural disasters, etc. In this case the AMS earth station (GDT) is deployed on the eastern coast of Sicily to provide a better radio coverage along the aircraft trajectory. Indeed, in most cases the GDT is transportable and relocated, on a mission- by-mission basis, wherever it may be necessary to optimize the mission execution. – The inland scenario include a VSAT FSS earth station with 2.4 m antenna (FSS1), pointed towards IS-903 satellite at 34.5W longitude, and an FSS earth station with 6 m antenna (FSS2) pointed towards Eutelsat 70B satellite at 70.5E longitude: also in this case, satellites currently in orbit have been selected to represent possible interference scenarios in case of spectrum sharing between FSS and AMS. Table 10-53 below summarizes the positions of GDT, FSS1 and FSS2 in the Coastal scenario and in the Inland scenario, as well as the FSS antennas pointing angles towards the applicable satellites.

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TABLE 10-53 GDT, FSS1 and FSS2 locations in Coastal and Inland scenarios

Coastal scenario Inland scenario

Site latitude 37.71226 N GDT site latitude 37.46678 N

GDT Site longitude 12.55176 E GDT GDT side longitude 15.0664 E Site altitude 15 m GDT site altitude 15 m

Site latitude 37.12522 N Site latitude 37.86269 N Site longitude 13.85503 E Site longitude 14.46663 E Site altitude 15 m Site altitude 1100 m 34.5 W 34.5 W Satellite longitude Satellite longitude FSS1 (e.g. IS-903) FSS1 (e.g. IS-903) Antenna true azimuth Antenna true 241.78 deg 241.89 deg angle azimuth angle Antenna Elevation Antenna Elevation 24.08 deg 23.25 deg angle angle

Site latitude 37.57823 N Site latitude 37.57823 N Site longitude 12.93660 E Site longitude 13.89798 E Site altitude 15 m Site altitude 1000 m 34.5 W 70.5 E Satellite longitude Satellite longitude FSS2 (e.g. Intelsat 903) FSS2 (e.g. Eutelsat 70B) Antenna true azimuth Antenna true 240.75 deg 112.02 deg angle azimuth angle Antenna Elevation Antenna Elevation 24.53 deg 17.52 deg angle angle

The following Figs 10-47 and 10-48 provide a graphical representation of the above locations, as well as a typical aircraft trajectory during the mission execution. The different colours along the trajectory curves qualitatively represent the aircraft climbing/descent phases, while the cruise/mission phase at constant altitude is represented by the red portion of the trajectory.

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FIGURE 10-47 Coastal scenario and aircraft/RPAS trajectory

FIGURE 10-48 Inland scenario and aircraft/RPAS trajectory

Rep. ITU-R S.2365-0 299

10.2.3.9.2 AMS airborne station operational mission parameters Table 10-54 summarizes the operational parameters that are considered in this analysis and are typically applicable to aircraft and RPAS of various categories during surveillance mission operations. These parameters will be used in § 10.2.3.8.5 to evaluate the impact of interference on mission execution.

TABLE 10-54 Aircraft/AMS airborne station operational parameters

Operational Cruise Type Typical platform altitude speed ID (up to km) (knots) (m/s) 1 Small Tactical RPAS 3 60 30 2 Helicopter 3 100 50 3 Tactical /Medium Altitude Long Endurance (MALE) RPAS 6 200 100 Medium/High Altitude Long Endurance (MALE/HALE) 4 10 300 150 RPAS 5 Fast patrol aircraft 10 400 200

10.2.3.9.3 AMS airborne station and FSS earth station transmitter and receiver characteristics Table 10-55 includes the characteristics of the AMS earth station (GDT), the AMS airborne station receiver (ADT) and FSS earth station transmitters (FSS1 and FSS2) for the considered scenarios. Parameters not impacting directly on the analysis are not shown for simplicity.

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TABLE 10-55 GDT, ADT, FSS1 and FSS2 characteristics in Coastal and Inland scenarios

Coastal scenario Inland scenario Transmitted bandwidth 3.5 MHz Transmitted bandwidth 3.5 MHz ITU-R ITU-R M.1851 M.1851 Antenna pattern diagram Antenna pattern diagram GDT (Cosine GDT (Cosine Distribution) Distribution) Antenna peak gain 40 dBi Antenna peak gain 40 dBi 3 dB aperture lobe 1.4 deg 3 dB aperture lobe 1.4 deg

Receiver bandwidth (BIF) 3.5 MHz Receiver bandwidth (BIF) 3.5 MHz

Noise Figure (NF) 4 dB Noise Figure (NF) 4 dB omnidirec- omnidirec- ADT Antenna type ADT Antenna type tional tional

Antenna gain (GR) 3 dBi Antenna gain (GR) 3 dBi

Installation losses (Linst) 1 dB Installation losses (Linst) 1 dB

Antenna diameter 2.4 m Antenna diameter 2.4 m Antenna pattern diagram ITU-R S.465 Antenna pattern diagram ITU-R S.465

Antenna peak gain (GT) 49.1 dBi Antenna peak gain (GT) 49.1 dBi FSS1 Transmission bandwidth FSS1 Transmission bandwidth 354 kHz 354 kHz (BT) (BT) TX Power Spectral TX Power Spectral –50 dBW/Hz –50 dBW/Hz Density (PSD) Density (PSD)

Antenna diameter 2.4 m Antenna diameter 6 m Antenna pattern diagram ITU-R 465 Antenna pattern diagram ITU-R 465

Antenna peak gain (GT) 49.1 dBi Antenna peak gain (GT) 57.1 dBi FSS2 Transmission bandwidth FSS2 Transmission bandwidth 354 kHz 354 kHz (BT) (BT) TX Power Spectral Density TX Power Spectral –50 dBW/Hz –50 dBW/Hz (PSD) Density (PSD)

Values in the above tables are chosen among the ones already identified earlier in the Report. In particular: 1 GDT characteristics have been referred to “System 1 Ground” defined in Table A-1 of the Annex of this Report 2 ADT characteristics have been referred to “System 6” defined in Table A-1 in of the Annex of this Report with the following notes:

– Receiver bandwidth 퐵퐼퐹 has been set to 3.5 MHz (within the range 0.85/120 indicated in Table A-1 of the Annex of this Report to better represent a typical value for air-to-ground AMS connections. Rep. ITU-R S.2365-0 301

– Noise figure has been set to 4 dB instead of 3.5 dB as indicated for “System 6” to better approximate the average noise figure level indicated for other airborne systems in Table A-1 of the Annex of this Report. This can be considered as a conservative approach, because the higher is the receiver floor noise level, the less the receiver can be interfered. 3 FSS earth station characteristics have been referred to the ones assumed for study #4 and #4A and summarized in Table 10-31 above with the following notes: – Reference frequency considered is 14.7 GHz instead of 14.6 GHz, to better represent a case in mobile defence harmonized band. – Antenna diameters considered in this analysis are 2.4 and 6 m.

– Transmitter bandwidth BT has been set at 0.354 kHz in both cases, as adopted for smaller antenna diameters in Study #1 and #2. This is an extremely conservative approach as the resulting FSS earth station e.i.r.p. which will be considered in the simulations to evaluate the interference impact is much lower than the one considered in other ITU-R studies. Considerations about possible variations of the above parameters and characteristics will be included in § 7 – Variance analysis – of this Contribution.

10.2.3.9.4 Simulation approach 10.2.3.9.4.1 Evaluation of receiver noise floor In order to determine the I/N interference level, it is necessary to evaluate the noise floor at the demodulator input. The receiver model considered for evaluation of the noise floor level is represented in Fig. 10-49.

FIGURE 10-49 AMS airborne station receiver model

The noise floor level for the AMS airborne station receiver – expressed in dBm (NdBm) – has been calculated as follows:

푁푑퐵푚 = 10퐿표푔10(푘퐵 ∙ 퐵퐼퐹 ∙ 푇푒푞퐴퐷푇) + 30 (10-4)

302 Rep. ITU-R S.2365-0 where: J 푘 = 1.38 10−23 is the Boltzmann constant 퐵 퐾

퐵퐼퐹 = 3.5 푀퐻푧 : bandwidth at demodulator input as indicated in Table 10-55

푇푒푞퐴퐷푇 : overall equivalent noise temperature of the AMS airborne station which is in turn defined as:

푇푒푞_퐴퐷푇 = 푇푎푛푡 + 푇푐표푛푛 + 푇푟푒푐푒푖푣푒푟 (10-5) where:

푇푎푛푡 = 290 퐾: assumed equivalent noise temperature of the airborne antenna

퐿푖푛푠푡/10 푇푐표푛푛 = 290 퐾 ∙ (10 − 1) = 75 퐾 : equivalent noise temperature of the RF connection between the antenna and the receiver input, assuming that such connection is at 290 K temperature and introduces 1 dB losses as indicated in Table 10-55

푁퐹/10 푇푟푒푐푒푖푣푒푟 = 290 퐾 ∙ (10 − 1) = 438 퐾 : equivalent noise temperature of the receiver, assuming that its temperature is equal to 290 K and the receiver noise figure is 푁퐹 = 4 푑퐵 as indicated in Table 10-55 Based on the above considerations, the overall equivalent noise temperature of the airborne antenna is Teq_ADT = 803 K, and the resulting noise floor level is:

푁푑퐵푚 ≅ −104 푑퐵푚 (10-6) Based on the above considerations, the maximum interferer level admissible at the demodulator input of the AMS airborne station receiver to satisfy the interference criteria defined in Recommendation ITU-R M.2068 (I/N ≤ −6 dB) is:

퐼푚푎푥 ≅ −110 푑퐵푚 (10-7) 10.2.3.9.4.2 Evaluation of interference power level at AMS airborne receiver The model considered for the evaluation of the interference level at AMS airborne station receiver is represented schematically in Fig. 10-50.

FIGURE 10-50 FSS to AMS connection model

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The interferer power level (I) received at the demodulator input of the AMS airborne receiver has been calculated as follows (values are indicated in dB).

퐼 = (푃푇 + 퐺푇) + (퐺푅 − 퐿푖푛푠푡) − 퐿푝푟표푝528(푑, 푓, ℎ1, ℎ2) (10-8) where:

푃푇 = 푃푆퐷 + 10퐿표푔10(퐵푇): the FSS transmitted power, 푃푆퐷 = −50 푑퐵푊/퐻푧 is the power spectral density transmitted by the FSS earth station and 퐵푇 = 0.354 푀퐻푧 is the FSS transmitted bandwidth, as indicated in Table 10-55

퐺푇: the FSS earth station antenna gain, variable in accordance with deviation from boresight direction in accordance with pattern diagram defined in Recommendation ITU-R S.465-6 [3]. Peak gain is assumed to be 49.1 dBi for a 2.4 m antenna at the reference frequency (f = 14.7 GHz) and 57.1 dBi for a 6 m antenna at the same frequency (see Table 10-55)

퐺푅 = 3 푑퐵𝑖: the AMS airborne station antenna gain; an omnidirectional pattern diagram is assumed as indicated in Table 10-55

퐿푖푛푠푡 = 1 푑퐵: the attenuation over the connection between AMS airborne antenna and AMS airborne receiver

퐿푝푟표푝528(푑, 푓, ℎ1, ℎ2): propagation losses over the air-to-ground aeronautical channel in accordance with Recommendation ITU-R P.528-3 [2]. The propagation losses are dependent from the slant range between FSS earth station and AMS airborne station (푑), the frequency at which the connection is established (푓), and the FSS and AMS antenna altitudes with respect to sea level (ℎ1 푎푛푑 ℎ2). Overall channel losses indicated in [2] may alternatively be expressed as the sum of free-space losses (in accordance with [3]) at the same range, plus additional losses to take in account atmospheric absorption effects. In particular, as channel losses in [2] are defined only for a few frequencies and antennas altitude configurations, interpolated values have been considered for this analysis whenever necessary. Finally, additional channel losses in [2] (over free-space losses) are defined as a function of probability of occurrence in time: values of 95%, 50%, 10% and 1% have been considered in this study.

10.2.3.8.4.3 Simulation environment setup The simulations presented in this Report have been performed through the commercial software tool ICS-Telecom manufactured by ATDI. The tool features an embedded Digital Terrain Model (DTM), including terrain maps with a precision of 25 m, to take in account obstruction effects due to earth orography. The ATDI software was used to determine the geographic extension of the areas around each FSS earth station in the operational scenario where the interference criterion (I/N calculated in accordance with hypotheses in §§ 5.1 and 5.2) is not met with a time probability (Lb) of 95%, 50%, 10% and 1%. Interference areas were calculated at different aircraft cruise altitudes (10 km, 6 km, 3 km) as indicated in Table 10-55. However, as the version of ICS-Telecom used in this study did not include natively the ITU-R P.528-3 propagation model, the following actions were taken:

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– Simulations were based on free-space propagation model in accordance with Recommendation ITU-R P.525-2 [1]. – ITU-R P.528 additional losses w.r.t to free-space losses were calculated for the AMS/FSS altitude configurations of interest, and various probability of occurrence. Such additional losses are variable with the range between FSS earth station and AMS airborne station; however, for simplicity reasons in this study an average constant value has been assumed. – The additional losses were taken in account by increasing, during the simulation, the maximum interferer level calculated in § 5.1 (Imax ≅ −110 dBm) by the corresponding values calculated as above. The following Tables 10-56 and 10-57 summarize the average additional losses assumed for the simulation and the resulting “free-space equivalent” values for maximum admissible level of interference (Imax _freespace). For instance, if we consider the case: – 95% probability of occurrence; – FSS earth station altitude: 15 m; – AMS airborne station altitude: 10 km. the average additional losses deriving from ITU-R P.528-3 interpolation are equal 11.80 dB. Therefore, in this condition the corresponding free-space equivalent max. interferer level considered in the simulation to evaluate the respect of I/N criterion becomes:

퐼max _푓푟푒푒푠푝푎푐푒 ≅ −110 dBm + 11.80 dB ≅ −98 dBm (10-9) The following Tables 10-56 and 10-57 show all the values for the additional losses and the resulting maximum interference level, for the three altitudes and the four likelihood of occurrence, considered in the two scenarios.

TABLE 10-56 Coastal scenario – P.528-3 additional propagation losses and adjusted simulation parameters

COASTAL SCENARIO

Additional propagation losses (i.a.w. P.528-3) Lb(0.01) Lb(0.10) Lb(0.50) Lb(0.95) w.r.t to free-space propagation (i.a.w. P.525-2) AMS airborne antenna altitude: 3 km –3.15 –0.86 3.00 12.14 AMS airborne antenna altitude: 6 km –2.52 0.00 3.50 12.34 AMS airborne antenna altitude: 10 km –2,80 –0.60 3.10 11.80

Resulting maximum interferent level Lb(0.01) Lb(0.10) Lb(0.50) Lb(0.95) for simulation AMS airborne antenna altitude: 3 km –113 –111 –107 –98 AMS airborne antenna altitude: 6 km –113 –110 –107 –98 AMS airborne antenna altitude: 10 km –113 –111 –107 –98 Rep. ITU-R S.2365-0 305

TABLE 10-57 Inland scenario – P.528-3 additional propagation losses and adjusted simulation parameters

INLAND SCENARIO

Additional propagation losses (i.a.w. P.528-3) Lb(0.01) Lb(0.10) Lb(0.50) Lb(0.95) w.r.t to free-space propagation (i.a.w. P.525-2) AMS airborne antenna altitude: 3 km –2.90 –0.91 2.37 9.70 AMS airborne antenna altitude: 6 km –2.60 –0.48 2.94 10.70 AMS airborne antenna altitude: 10 km –2.90 –0.80 2.60 10.50

Resulting maximum interferent Lb(0.01) Lb(0.10) Lb(0.50) Lb(0.95) level for simulation AMS airborne antenna altitude: 3 km –113 –111 –108 –100 AMS airborne antenna altitude: 6 km –113 –110 –107 –99 AMS airborne antenna altitude: 10 km –113 –111 –107 –100

10.2.3.9.5 Analysis of interference areas The following §§ 10.2.3.9.6 and 10.2.3.9.7 include the simulation results. Geographical areas where the FSS-over-AMS protection criterion is not met are plotted, for the Coastal and Inland scenarios, as two-dimensional areas at constant AMS airborne station altitude. Interference areas have been evaluated for altitude values of 10 km, 6 km and 3 km are shown, in accordance with the reference operational parameters indicated in Table 10-54. Each interference area is defined through a coloured palette with the following meaning: – The red zone (Lb(95%)) represents the area in which I/N is higher than −6 dB with a time probability of 95% or above; – The orange zone (Lb(50%)), which includes the red one, represents the area in which I/N is higher than –6 dB, with a time probability of 50% or above; – The yellow zone (Lb(10%)), which includes the previous two, represents the area in which I/N is higher than –6dB, with a time probability of 10% or above; – The blue zone (Lb(1%)), which includes all the other inner zones, represents the area in which I/N is higher than –6dB, with a time probability of 1% or above. Outside the coloured area, I/N exceeds –6 dB for a time probability below 1%. Based on previous considerations, and considering the definition of the protection criterion included in [6], it is possible to conclude that the AMS protection criterion due to FSS interference is not met inside the blue zone.

10.2.3.9.6 Coastal scenario analysis Figure 10-51 represents the interference area induced by FSS1 earth station in the Coastal scenario. As indicated by the coloured palette, the quasi-deterministic interference area (I/N >–6dB with time probability of 95% or above) has an extension of about 6 × 13.5 km.

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FIGURE 10-51 Coastal scenario – FSS1 station interference at 10 km altitude

Considering the typical aircraft speed listed for aircraft “type 4” and “type 5” (150-200 m/s, see Table 10-54), the minimum time required to cross this interference area (and the corresponding link interruption duration between AMS earth station and AMS airborne station) would be in the order of 40 or 30 seconds, respectively. Moreover, considering that when the AMS airborne station is within the red area in the reference scenario: – the distance between GDT and ADT is in the order of 150 km (a typical operational range for this kind of services); – the corresponding GDT antenna linear coverage in the horizontal plane at such distance is about 3.7 km (aperture lobe 1.4 degrees, see Table 10-55), i.e. lower than the interference area extension. For this reason, when the aircraft transits through the red interference area the link interruption would determine a total tracking loss by the AMS ground antenna, as the aircraft would exit from the main lobe before the link could be re-established1. In such conditions, in most practical systems a link recovery procedure must be initiated, i.e. the aircraft must reach a pre-planned position (“rendez-vous point”) and a search pattern must be executed by AMS earth station antenna until the link with the AMS airborne station is re-established. In order to ensure that the recovery procedure is successful, the rendez-vous point must be placed outside the 1% interference zone. Considering its extension, the flight time required for an aircraft “type 4” and “type 5” to exit from such interference area varies from about 70-90 s (time to cross half

1 Note that the GDT linear coverage would remain lower than the minimum 95% interference area extension up to a range of 250 km between the AMS earth station and AMS airborne station. Rep. ITU-R S.2365-0 307 the interference area along its minor axis) to about 150-200 s (time to cross half the interference area long its major axes). Similar considerations may be done considering the aircraft transiting through the 50% or 10% interference areas (orange/yellow areas): the level of probability of a AMS link loss and a subsequent tracking loss by the AMS earth station is still unacceptable, and the crossing time to exit from the interference zone is still largely depending on the extension of the 1% interference area. Figures 10-56 and 10-57 below show the interference scenario at 6 km and 3 km altitude. Comparing the cases at 10 km and 3 km altitude, the interference area extension reduction with respect is about 30% in distance along the major axis. However, aircraft speed at this altitude can be much lower. For instance, a “type 1” aircraft as defined in Table 10-54 would fly at 60 m/s. By comparison with the speed of a “type 5” aircraft (200 m/s), that means a 330% increment of time required to go through the same distance. Such factor largely overcomes the reduction of interference area extension with altitude.

FIGURE 10-52 Coastal scenario – FSS1 earth station interference at 6 km altitude

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FIGURE 10-53 Coastal scenario – FSS1 earth station interference at 3 km altitude

The following Table 10-58 summarizes the above considerations in the most significant cases at 10 km, 6 km and 3 km altitude for the FSS1 earth station.

TABLE 10-58 Coastal scenario – FSS1 interference impact on operational mission

FSS zone where the protection criterion is not met Coastal scenario AMS FSS 2.4 m antenna Extension Time to cross ground station Aircraft total Altitude Length Width min max Speed tracking loss km m/s km km s s 200 133.5 309 Yes 10 61.7 26.7 150 178 411.3 Yes 6 100 51 24.5 245 510 Yes 50 500 940 Yes 3 47 25 30 833 1566.7 Yes

It is important to notice the “Time to cross” values in the table above, which provide an indication of the average estimated AMS service interruption duration after a link loss induced by FSS1 interference. It is apparent that such values are not acceptable from the operational point of view and lead, de facto, to the need to plan the aircraft mission trajectory avoiding any crossing in the FSS interference area. As a consequence this would imply the impossibility to execute the surveillance mission inside the interference zone. Rep. ITU-R S.2365-0 309

In the Coastal scenario, FSS2 earth station is assumed to have the same characteristics as FSS1 and be installed in similar conditions (FSS2 antenna altitude 15 m, see Table 10-53): therefore the quantitative evaluations in Table 10-58 apply also to FSS2 interference. The following three Figures show the interference zones configuration when both FSS1 and FSS2 earth station are introduced in the Coastal scenario. Figure 10-54 represents interference at 10 km altitude, while Fig. 10-55 and Fig. 10-56 include the scenario at 6 km and 3 km, respectively. The aircraft trajectory during the operational mission is superimposed on the FSS interference figures to provide a graphical representation of the overall situation. Taking into account the previous considerations, it is apparent that the presence of multiple FSS earth stations would have a strong impact on AMS service continuity and impose heavy restrictions over the planning of AMS operational missions, with the exclusion of significant portions of territory from the surveillance areas.

FIGURE 10-54 Coastal scenario – FSS1+FSS2 earth station interference at 10 km altitude

FIGURE 10-55 Coastal scenario – FSS1+FSS2 earth station interference at 6 km altitude

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FIGURE 10-56 Coastal scenario – FSS1+FSS2 earth station interference at 3 km altitude

10.2.3.9.7 Inland scenario The Inland scenario (see Table 10-53 and Fig. 10-48) envisages two FSS earth station types, FSS1 with 2.4 m antenna diameter, and FSS2 with 6 m antenna diameter. In this case, both FSS antennas are supposed to be installed at an altitude of about 1 000 m over sea level, while the AMS earth station (GDT) is located along the east coast of Sicily to provide best radio-frequency coverage during the specific mission. Figure 10-57 in the next page shows the FSS1 interference areas where I/N > –6dB at various levels of probability (with the same meaning described in § 6) and an aircraft/AMS airborne station flying at an altitude of 10 km; Fig. 10-58 represents the FSS2 interference areas in the same hypotheses. It is easy to conclude that in both cases the areas in which the AMS protection criterion, due to FSS interference, is not met (i.e. inside the blue zone boundaries) is similar or larger than the one induced by FSS1 earth stations in the Coastal scenario at the same altitude, therefore all considerations made in § 6.1, about crossing time at a fixed aircraft cruise speed, do apply in the Inland scenario. Also, total tracking loss after AMS link interruption due to interference is predictable, as the distances involved between the AMS earth station (GDT) and the AMS airborne station (ADT) are in the order of 40-100 km. Similar conclusions may be drawn for 6 km and 3 km aircraft altitude cases (not shown here for simplicity reasons). The following Tables 10-59 and 10-60 summarize the impact of FSS1 and FSS2 interference on the operational mission.

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TABLE 10-59 Inland scenario – FSS1 interference impact on operational mission

Inland scenario FSS zone where the protection criterion is not met AMS FSS 2.4 m antenna ground Interference area Time to cross station Altitude Aircraft Length Width min max total Speed tracking loss km m/s km km s s 10 200 63 27 135 315 Yes 150 180 420 Yes 6 100 52.3 24.7 247 523 Yes 3 50 34.1 19.7 394 682 Yes 30 657 1136.7 Yes

TABLE 10-60 Inland scenario – FSS2 interference impact on operational mission

Inland scenario FSS zone where the protection criterion is not met AMS FSS 6 m antenna ground Extension Time to cross station Altitude Aircraft Length Width min max total Speed tracking loss km m/s km km s s 10 200 87 28 140 435 Yes 150 187 580 Yes 6 100 72.1 27.2 272 721 Yes 3 50 67.2 28.4 568 1344 Yes 30 947 2240 Yes

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FIGURE 10-57 Inland scenario – FSS1 interference at 10 km altitude

FIGURE 10-58 Inland scenario – FSS2 interference at 10 km altitude

The following three Figures show the interference zones’ configuration when both FSS1 and FSS2 earth stations are introduced in the Inland scenario. Figure 10-59 represents interference at 10 km altitude, while Fig. 10-60 and Fig. 10-61 include the scenario at 6 km and 3 km, respectively. The aircraft trajectory during the operational mission is superimposed on the FSS interference figures to provide a graphical representation of the overall situation. Taking into account the previous considerations, it is apparent that also in this case the presence of multiple FSS earth station would have a strong impact on AMS continuity and impose significant restrictions over the planning of AMS operational missions, with the exclusion of significant portions of territory from the surveillance areas. Rep. ITU-R S.2365-0 313

FIGURE 10-59 Inland scenario – FSS1+FSS2 earth station interference at 10 km altitude

FIGURE 10-60 Inland scenario – FSS1+FSS2 earth station interference at 6 km altitude

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FIGURE 10-61 Inland scenario – FSS1+FSS2 earth station interference at 3 km altitude

10.2.3.9.8 Variance analysis The scope of this section is to make some considerations about the sensitivity of the previous results with respect to variations of the main parameters considered in the Coastal and Inland scenarios.

10.2.3.9.8.1 Frequency variation Analyses in this Report are referred to a transmission frequency of 14.7 GHz. In order to extend the results to the whole bands 14.5-14.8 GHz and 14.8-15.35 GHz, the spreadsheet contained in [5] has been used to determine the variations of the FSS earth antenna peak gain and main lobe aperture; circular aperture shape and 60% antenna efficiency have been assumed as hypotheses. The following Table 10-61 summarizes the FSS earth antenna gain and aperture lobe variations vs. frequency.

TABLE 10-61 FSS earth antenna parameters variations vs. frequency

Frequency Reference = 14.5 GHz 15.35 GHz 14.7 GHz

FSS Lobe Delta Lobe Delta Delta Lobe Peak Peak Peak Delta vs. antenna aperture vs. aperture vs. vs. aperture gain gain gain reference diameter @ –3dB reference @ –3dB reference reference @ –3dB m dBi deg dBi dBi deg deg dBi dBi deg deg 2.4 49.14 0.589 49.02 –0.12 0.597 0.008 49.51 0.37 0.564 –0.025 6 57.10 0.236 56.98 –0.12 0.240 0.004 57.47 0.37 0.226 –0.01

Considering that the FSS earth antenna gain is the driving factor to determine the “length” of the FSS interference zone (major axis), while the lobe aperture is the driving factor to determine the “width” of the same zone (minor axis), it can be predicted that: Rep. ITU-R S.2365-0 315

– The gain variation for both 2.4 and 6 m diameter antennas (from −0.12 at 14.5 GHz to +0.37 dBi at 15.35 GHz, with respect to reference) would have a limited impact on the extension of the FSS interference areas along the bore sight direction (1.4% extension reduction at 14.5 GHz to 4.4% extension increase at 15.35 GHz). – The lobe aperture angle varies, in the worst case (2.4 m diameter antenna), from +0.008 degrees at 14.5 GHz to –0.025 degrees at 15.35 GHz, with respect to reference. This implies that at 150 km distance from the FSS earth station the main lobe coverage is increased or decreased by less than 100 m. It can be predicted, therefore, that a similar variation is applicable to the width of the interference zone when passing from 14.5 GHz to 15.35 GHz. As a conclusion, it is possible to affirm that the results of the present analysis do not depend significantly from the assumed reference frequency within the bands 14.5-14.8 GHz and 14.8-15.35 GHz.

10.2.3.9.8.2 FSS earth station transmitted power This study has been based upon the hypothesis that the FSS earth station transmits at −50 dBW/Hz power supply density (PSD) over a 354 kHz bandwidth (see Table 10-54) in § 4 of this Report. As anticipated, this is a very conservative approach, as other ITU-R studies #3, #4 and #4A as reported in Table 10-31 in § 10.2.3.1 do consider a transmitted bandwidth of 10 or 36 MHz. Should one of these assumptions be made in this analysis, this would imply to consider that the FSS earth station transmits at constant PSD over the whole bandwidth of the AMS airborne station (BIF = 3.5 MHz, see again Table 10-54 in this Report). As a consequence, the interferer power level at the AMS receiver would be increased by a factor of 10, equivalent to 10 dB increase. In this case, the resulting interference zones induced by FSS earth station on the AMS airborne station would be much more extended than the ones shown in the previous section. Figure 10-62 shows, for instance, the new extension of the FSS1 interference in the Coastal scenario, while Fig. 10-62 shows the impact of FSS1 and FSS2 earth station interference over the aircraft trajectory.

FIGURE 10-62 Coastal scenario – FSS1 interference zone at 10 km altitude (FSS1 transmitted bandwidth ≥ 3.5 MHz)

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FIGURE 10-63 Coastal scenario – FSS1+FSS2 interference zone at 10 km altitude (FSS1 transmit bandwidth ≥ 3.5 MHz)

10.2.3.9.9 Conclusions of Study #6 Analyses have demonstrated that, in the considered scenarios, a single FSS earth station generates an interference zone, where the protection criterion indicated in [6] is not met. The extension of such zone, notwithstanding the low values for the transmitted bandwidth of the FSS earth station assumed in the simulation (see Table 10-54), reaches several tens of km. Moreover, the interference zone extension overcomes 100 km length when considering an FSS transmitted bandwidth equal or larger than the AMS receiver bandwidth (i.e. 3.5 MHz, see § 7.2 of this study). The latter hypothesis is coherent with the assumptions made in studies #3, #4 and #4A. Considering various aircraft types and their relevant cruise speed from 60 to 400 knots (30 to 200 m/s), the interference duration, within the above zones, is in the order from several tens of seconds to several minutes. In all cases, considering the typical characteristics of the AMS ground station antenna, the resulting link loss between the AMS airborne station and AMS earth station is long enough to cause, in practical terms, a total loss of tracking by the AMS earth station. As a consequence, a link recovery procedure must be initiated, i.e. the aircraft must reach a pre-planned position (rendez-vous point) and a search pattern must be executed by AMS ground station antenna until the link is re-established. In order to ensure that the recovery procedure is successful, the rendez-vous point must be placed outside the interference zone (i.e. outside the 1% area): for the same reasons, a flight time from some minutes to ten of minutes may be required before the AMS link is re-established and the mission can be resumed. The analyses performed have demonstrated that these considerations apply at various aircraft altitudes (10 km, 6 km, 3 km) which may be considered as typical for the various types of aircraft using this type of AMS application. Moreover, analyses have demonstrated that the above considerations are almost independent from the operational frequency chosen in the band 14.5-14.8 GHz and 14.8-15.35 GHz. Rep. ITU-R S.2365-0 317

The above results bring to the following considerations: – in presence of an FSS earth station operating in the bands 14.5-14.8 GHz and 14.8-15.35 GHz, in order to avoid unacceptable service interruptions on the AMS, the aircraft trajectory should be planned outside the 1% interference zone generated by the FSS earth station; – in case of installation of multiple FSS earth stations in the same area, this exclusion should be applied to all FSS interference areas; – considering that AMS operating in both the bands 14.5-14.8 GHz and 14.8-15.35 GHz are typically correlated with governmental aerial surveillance operations (for prevention of refugees migration, smuggling, traffic of weapons, etc.; monitoring public order and safety during major events or natural disasters; safeguarding national/international security), it is inherently impossible to pre-plan aerial surveillance missions, as they must be executed anywhere the circumstances are generating an operational need. Moreover, AMS ground station position is normally defined on a mission-by-mission basis to guarantee the best coverage of the whole aircraft trajectory. Based on the above considerations, the installation of FSS earth stations operating in the bands 14.5-14.8 GHz and 14.8-15.35 GHz could lead to the exclusion of large parts of territory and unacceptable operational impacts on execution of aerial surveillance missions using AMS services, including national/international security in case of governmental operations.

10.2.4 FSS (E-s) and MS (Land Mobile Service) Study #1 examines the interference from a VSAT earth station operating in the FSS (here after referred to as VSAT) into a MS station and estimates the required separation distance for protection of MS station. The 14.5-15.35 GHz frequency range is allocated to the fixed and mobile services on a primary basis in all three ITU Regions. The 14.5-14.8 GHz frequency band is also allocated to the FSS (Earth-to-space) on a primary basis in all three ITU Regions limited to feeder links for the broadcasting satellite service for Administrations outside Europe. Study #2, also in the 14.5-15.35 GHz, considers the dynamic nature of the mobile service and the FSS earth station transmissions. This considers the interference from a transmitting FSS earth station into a receiving MS terminal when they are operating in the same area over a period of time.

10.2.4.1 FSS/ VSAT (E-s) parameters For Study #1, the VSAT station parameters assumed for this study are provided in Table 10-36. These parameters are based on the FSS earth station characteristics shown above in § 4 of this Report. Since the 1.2 m diameter antenna with a PSD of –42 dBW/Hz and an antenna gain of 42.7 dBi represents the worst case e.i.r.p. spectral density towards the direction of MS mobile station, the characteristics of this antenna and the corresponding PSD value were used in this study. Furthermore, a frequency of 14.6 GHz was assumed and the VSAT transmit antenna is assumed to be mounted on a tower for Study #1, with the transmit e.i.r.p. towards the received victim station is calculated using the given parameters. The parameters are shown in Table 10-62.

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TABLE 10-62 Parameters used for the FSS in Studies #1 and #2

Parameter Study #1 Value Study #1 Note Study #2 Value Satellite(transmit) Downlink e.i.r.p. spectral –20 dBW/Hz N/A N/A density (dBW/Hz) FSS earth station VSAT (transmit) (transmit) Frequency 14.6 GHz 14.6 GHz Transmitted bandwidth N/A MHz The VSAT transmitted bandwidth is assumed to be at least as great as 354 kHz the minimum AMS aircraft’s bandwidth. Antenna min. elevation 10 deg 10 deg angle (θt) Antenna diameter 1.2 m 0.75 m Antenna height 15 m From dish center to ground; 10 m Height above the terrain

Antenna gain pattern (GT) Rec. ITU-R BO.1213 BO1213/S.1855

Antenna peak gain (G0t) 42.7 dBi 39.3 dBi

Terrain elevation angle (εt) Variable deg Varies depending on Variable deg azimuth direction Antenna gain towards Variable dBi Varies depending on AMS aircraft (Gt) the terrain, elevation Variable dBi and azimuth direction Max. transmit PSD –42; –50; dBW/Hz –57 dBW/Hz –55; –59 NOTE 1 – The transmit PSD of –42 dBW/Hz is derived from Recommendation ITU-R S.728. This level is 8 dB higher than one known administration’s domestic rules for routine licensing of VSAT earth stations. NOTE 2 – The transmit PSD of –57 dBW/Hz is derived from the mean of one satellite operators peak PSD levels that are in operation today in the 14-14.5 GHz band. The –57 dBW/Hz as the mean is derived from a methodology that may notably underestimate the mean. In study #2, a single earth station is modelled, however, since it is operating at 100% of the time, it could overestimate the interference from a single earth station that operates less than 100% of the time.

NOTE 3 – The Antenna min. elevation angle (θt) of 5 degrees may be too low for VSAT terminals to be able to close the link and antenna minimum elevation angle of 10 degrees may be more typical for VSAT terminals. NOTE 4 – The Antenna height of 15 m may be higher than what is typically used for VSAT terminals.

Rep. ITU-R S.2365-0 319

10.2.4.2 Study #1 The Study #1 analysis examines potential interference to mobile stations operating in the 14.5-15.35 GHz band resulting from FSS uplinks. ITU Region 1 is examined through one representative MS location. The analysis determines appropriate separation distances which describe a non-uniform area within which a VSAT station has the potential of causing harmful interference. The MS mobile station protection criteria used in this analysis are given in Document 4A/150 as an I/N of –6 dB. The interference from a VSAT station transmitter into the MS mobile station receiver normally arises under trans-horizon propagation and not under line of sight conditions. Figure 10-64 shows the potential interference scenarios (in dotted lines) to mobile station links and FSS Satellite (GSO).

FIGURE 10-64 Interference scenarios from proposed VSAT in the FSS allocations to mobile station

FSS VSAT Interfering into MS systems MS Systems Intefering into FSS Satellite GSO

10.2.4.2.1 Study #1 Representative MS locations The MS mobile stations may operate anywhere in ITU Region 1. Typical site in ITU Region 1 to be analysed is given in Table 10-63.

TABLE 10-63 Sample mobile sites in three ITU Regions operating in the 14.5-15.3 GHz band

Latitude Longitude Representative location Country Region (deg N) (deg E) Cambridgeshire England 1 52.37 –0.23

10.2.4.2.2 Study #1 FSS/VSAT and mobile station parameters & analysis assumptions The mobile station parameters used in the simulations are given in Table 10-64.

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TABLE 10-64 Parameters used for mobile stations

MS station parameter Value Units Notes Frequency 14.6 GHz Assumed received frequency for all stations and transmitting frequency for VSAT Bandwidth N/A MHz The received bandwidth is at least 2.46 MHz. The VSAT transmitted bandwidth is assumed to be at least as great as the minimum mobile station’s bandwidth. Antenna height 13 m From dish center to ground; Height above the terrain Transmitted Power 16 dBW Document 4A/150 Maximum antenna gain 25 dBi Document 4A/150 I/N permissible interference –6.0 dB Document 4A/150 level Noise figure 4.0 dB Document 4A/150 Probability of exceedence (p) 0.1 % For trans-horizon interference sources (Rec. ITU-R due to weather statistics SA.609); Using Rec. ITU-R P.452 propagation model

The refractive index, ΔN and surface refractivity, N0 used with Recommendation ITU-R P.452 are provided in Table 10-65.

TABLE 10-65

Refractive index, ΔN and surface refractivity, N0 used with Recommendation ITU-R P.452

Representative location Refractivity Surface refractivity, N0 index, ∆N Cambridgeshire 47 330

The minimum propagation loss, Lmin in dB, required from the VSAT transmitter to the mobile station receiver is given by:

퐿푚푖푛 = 푒. 𝑖. 푟. 푝.푇푥− 푃푟표푡푒푐푡𝑖표푛퐶푟푖푡푒푟푖푎푅푥 + 퐺푅푥 – 푁 e.i.r.p.Tx is the spectral density transmitted in any direction towards the victim receiver station by the VSAT. The protection criterion for the Mobile station is I/N of –6 dB. The received victim antenna gain, Grx, is an off-boresight gain toward the interfering VSAT. N is the received victim noise temperature. Using the above parameters, the minimum propagation loss to meet the protection of the mobile station is dynamically calculated at every coverage grid point. Other simulation assumptions are as follows: 1) A VSAT may communicate to any GSO satellite on the GSO arc with a minimum of 10 degrees elevation angle. 2) The victim mobile station may be in any orientation with respect to a VSAT earth station. Rep. ITU-R S.2365-0 321

3) Only one interfering VSAT is used. Multiple VSATs, transmitting to the same satellite on the same frequency, can generate aggregate interference that could potentially be higher than what is calculated in this contribution depending upon the actual VSAT density and geographical distribution. It should be noted, however, that VSAT earth stations that are part of the same system typically share a narrow bandwidth (< 2 MHz) on a time division basis, and typically operate at lower power densities than –42 dBW/Hz. 4) The area of analysis is sampled at 5  5 km. 5) Employed Recommendation ITU-R P.452 propagation model with a 30 arc second (1 km) resolution global terrain data and ITU Digitized World Map (IDWM) for interference into mobile station. 6) Areas where the interference value is greater than the recommended threshold are colored in red and areas where the interference is below the required threshold are not colored.

10.2.4.2.3 Study #1, case 1: FSS (E-S) interference into Mobile Station The simulation result for one representative station is shown in Fig. 10-65 below. The maximum value of the minimum required separation distances is summarized in Table 10-66. Due to the terrain height at different geographic areas resulting in a longer line-of-sight (LOS) distance, the results are typically worse than for the smooth earth case. The maximum values of the minimum required separation for a representative location, which are located in ITU Region 1, and not accounting for terrain obstruction is 42 km for MS stations.

TABLE 10-66 Maximum required separation distances between FSS/VSAT and MS station in the 14.5-15.35 GHz band

Figure 10-65 shows the land mobile coordination contour, not accounting for terrain obstruction, around Cambridgeshire, England. To meet the land mobile protection criteria, the required separation distance for VSAT transmitters ranges up to approximately 42 km.

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FIGURE 10-65 Coordination contour around Cambridgeshire, England, No Terrain

10.2.4.2.4 Study #1, Case 2: Mobile Station Interference into FSS GSO Summary Since the MS station’s antenna can track the MS base station above the horizontal plane, there will be times at which the MS station’s antenna beam over its horizontal scanning range can be pointing at or near a satellite in the geostationary satellite orbit. These are cases where there are low elevation angles of the satellite and the line between the mobile station and mobile base station points towards the GSO arc. During periods when the MS station in the main beam of FSS GSO, the FSS GSO receiver may receive levels of interference that exceed the –12 dB threshold if the band is allocated to the FSS in the earth-to-space direction. The G/T of a receiving space station in the GSO is required to calculate the I/N produced by MS station into a GSO satellite receiver. As indicated in Table 10-42 above, Annex 10 to Document 4A/343 does not provide typical G/T values of GSO space station receivers in this portion of the spectrum. A partial survey of the most recent notifications of satellite networks listed in the ITU-R’s Space Network Systems (SNS) database was conducted over a range of longitudes in the three ITU Regions. A range of typical values was assumed for this analysis in terms of the highest (17 dBK-1), median (7 dBK-1) and lowest (–6 dBK-1) G/T values, designated as Case 2(a), Case 2(b) and Case 2(c), respectively, as indicated from the data in Table 10-67.

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TABLE 10-67 GSO Space Station G/T Values

GSO arc Networks Maximum G/T Median G/T Minimum G/T Region examined considered Case 2(a) Case 2(b) Case 2(c) 1 –5° – 35° East 49 16.9 dBK–1 9.37 dBK–1 –6.61 dBK–1 2 –120° – 75° East 43 13.22 dBK–1 4.27 dBK–1 –6.6 dBK–1 3 70° – 130° East 73 22.01 dBK–1 7.59 dBK–1 –6.13 dBK–1 Typical values assumed for analysis 17 dBK–1 7 dBK–1 –6 dBK–1

Link calculations are presented in Table 10-68 for each of these cases, a satellite channel bandwidth of 10 MHz for calculating satellite receiver noise power. The resulting I/N calculated under free space propagation conditions is compared to an FSS space station I/N threshold of –12.2 dB, corresponding to the ∆T of 6% for 100% of the worst month criterion of Recommendation ITU-R S.1432. As indicated in the table, this I/N threshold is exceeded in two of the three examples presented in the Table 10-24 considering the worst case situation (i.e. MS/AMS TX station located exactly in the line of sight of the GSO FSS and the MS/AMS RX station). Nevertheless, considering the nature of the MS/AMS TX and RX stations, the time period when the MS/AMX RX station is in this worst case situation is very limited if any.

TABLE 10-68 Calculation of interference from MS station into GSO space station receiver

N/A

Satellite antenna discrimination may be required to protect GSO satellite receivers from MS station emissions since antenna pointing restrictions on MS station’ antennas are not practical. The normal satellite antenna gain roll-off towards the Earth’s limb in this portion of the spectrum may be sufficient to protect GSO satellite receivers from emissions from the MS station whose antennas do not point above the horizontal plane.

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10.2.4.2.5 Study #1 Summary for VSAT in the FSS and MS sharing With respect to interference into MS systems for the 14.5-15.35 GHz band, there is a potential for interference from the proposed 14.5-15.35 GHz FSS/VSAT Earth-to-space allocation to the MS station when a VSAT terminal in the FSS is in the vicinity of the MS station. It is necessary that interference to the AMS in the 14.5 15.35 GHz be such that the protection criterion is not exceeded. The separation distances resulting a non-uniform area to protect a representative location in ITU Region 1 is shown in Table 10-66. In some cases, due to the terrain height at different geographic areas resulting in a longer line-of-sight (LOS) distance, the results may be worse than for the smooth earth case. The maximum values of the minimum required separation distance for the one representative location, which is located in ITU Region 1, and not accounting for terrain obstruction is 42 km for MS stations. Due to the terrain height at different geographic areas resulting in a longer line of sight (LOS) distance, the results may be worse than for the smooth earth case; however, this is very site dependent. It is to be noted that this analysis is based on the presence in the area of a single VSAT operating on a single channel. The analysis shows that in order to protect the MS mobile station receiver operating in the 14.5-15.35 GHz band in ITU Region 1, a separation distance of up to 43 km (not accounting for terrain obstruction) describes a non-uniform area around a MS mobile station where the protection criteria is exceeded. The terminal on the ground on the MS can be fixed or mobile. When the MS system moves, so does the associated non-uniform area. In order to ensure protection for the current and future MS operations, the protection criteria within this non-uniform area must be met. With respect to interference into FSS GSO, since the main beams of such MS systems can point toward the GSO, FSS space stations may be subject to unacceptable levels of interference over periods of time from MS systems operating under the existing primary allocation in this band. This should be taken into account in developing any methods.

10.2.4.3 Study #2 10.2.4.3.1 Assumptions and methodology Study #2 considers the dynamic nature of the mobile service and the FSS earth station transmissions. This considers the interference from a transmitting FSS earth station into receiving MS stations when they are operating in the same area but with randomized parameters. The output is I/N statistics at the MS station receiver collected at each iteration of the Monte Carlo analysis. A FSS earth station is deployed as described above in Table 8-16 which contains the antenna size, input power spectral density and bandwidth. The FSS earth station is assumed to be in Canada and sharing the same territory as the MS terminal. Terrain data for this area in Canada was included in the analysis. There are assumed to be 40 GSO satellites spaced every 3 degrees and having receive coverage of the Canadian territory such that the minimum elevation angle of the FSS earth station is 10 degrees. This single FSS earth station using all of the bandwidth and transmitting 100% of the time and pointing towards one of the 40 GSO satellites at every time step of the simulation is assumed to be, for the purposes of this study, equivalent to multiple earth stations in the area transmitting to different satellites with a certain bandwidth and an inherent duty cycle depending on the type of transmission. The analysis does not account for simultaneous transmissions from different terminals in this same geographic area or from dispersion of terminals over the area of analysis. As a next step, the analysis could take into account a more detailed deployment scenario for FSS earth stations in the area under analysis including VSATs, wideband and point-to-point earth station transmissions. In addition, further consideration could be given to defining the area around an earth Rep. ITU-R S.2365-0 325 station where you would have interference while the earth station in question is transmitting. For example, there could be multiple earth stations operating in this area, each transmitting to different satellites. These would result in different geometries and associated distribution of the interference area. However, there are mitigating factors that should be taken into fact, including: if a large number of VSAT terminals are modelled, their narrowband nature and time division access techniques should be taken into account. The MS parameters are shown in Table 10-64 above. The MS stations are assumed to have a random location within a square that has a 94 × 94 km area (approximately) around the FSS earth station with random antenna pointing always toward the MS base station. An antenna height of 4 m and 13 m were both considered (following the parameters of System 4 in Annex 23 of Document 5A/306). The area of 94 × 94 km was chosen in consideration of the approximate radial line of sight distance associated with these mobile terminals. The results are displayed in I/N statistics collected at the MS mobile station receiver based on the interference received from the FSS earth station at each interval of the Monte Carlo analysis. The Monte Carlo analysis was run for 10,000 iterations. Table 10-69 defines the random variables used in the analysis.

TABLE 10-69 Random variable definition for parameters used in MS Study #2

Random Variable Definition Distribution MS mobile latitude 50.63N ± 47 km Uniform MS mobile longitude 96.32W ± 47 km Uniform MS base station latitude 50.63N ± 47 km Uniform MS base station longitude 96.32W ± 47 km Uniform FSS earth station antenna pointing 1 of the 40 GSO satellites Uniform

It is noteworthy that in the simulation, the location of the FSS earth station remained constant in the center of the square box, i.e. constant at 50.63° N, 96.32° W.

10.2.4.3.2 Study #2 Analysis results The output of Study #2 is a plot of the I/N statistics at the MS mobile station receiver collected at each iteration of the Monte Carlo analysis. The plot shown in Fig. 10-66 contains the I/N statistics at the MS mobile station receiver when it has a height of 4 or 13 m. Based on this analysis, the I/N criterion of –6 dB for the MS receiver is exceeded. The criterion is to be met 100% of the time. From this plot, the MS protection level of an I/N of –6 dB is met for 85% of the time for an MS mobile station receiver at both 4 and 13 m in height.

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FIGURE 10-66

MS receive I/N for a mobileMS station receive antenna link I/N heightstatistics of 4 and 13 m above the terrain

100

10 MS height of 4 m

0.1

Iterations (normalized %) Iterations (normalized

0.01 MS height of 13 m

0.001 -30 -24 -18 -12 -6 0 6

I/N (dB)

10.2.5 FSS (s-E and E-s) and space research service 10.2.5.1 SRS characteristics The frequency band 14.5-14.8 GHz is used by SRS data relay satellite systems for forward feeder links (Earth-to-GSO DRS) and for return inter-orbit links (NGSO user spacecrafts-to-GSO DRS). Figure 9-9, taken from Recommendation ITU-R SA.1018, shows a hypothetical reference system representing a DRS. The technical characteristics of transmitting Earth and space stations and receiving DRS space stations presented in Recommendation ITU-R SA.1414. The protection criteria for the various links of data relay satellite systems are provided in Recommendation ITU-R SA.1155. ITU-R Space Radiocommunication Stations Data Base (version February 2013) contains information on 49 forward feeder links and 6 return inter–orbit links that use frequency band 14.5-14.8 GHz for DRS feeder links. Table 10-70 shows the typical parameters used by SRS DRS systems.

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TABLE 10-70 Technical Parameters used for DRS system cases

Parameters DRS Uplink DRS Return Transmit Station WSC, USA ISS Receive Station TDRS 49W TDRS 49W Satellite Altitude (km) 500 km (ISS); 35786 km (DRS) Satellite Inclination (deg) 51.6 deg (ISS); 0 deg (DRS) Bandwidth (MHz) 650 44 RF transmit power level (dBW) 30 8.3 Maximum transmit PSD (dBW/Hz) –58.0 –68.1 Satellite Antenna pattern S.672 Ground Station Antenna Pattern F.699 Tx Station Antenna gain (dBi) 66.4 46 Rx Station Antenna gain (dBi) 46 53.3 Rx Station Temperature (k) 2537 907 Aggregate Interference Criteria Rec. SA.609 SA.1155 Aggregate Interference Protection criteria (Io/No, dB) –6 dB –10 dB % time for the protection criteria 0.1% Apportionment of Total interference to FSS Rec ITU-R SA.1743

10.2.5.2 FSS characteristics Table 10-71 shows the FSS system typical parameters taken from Table 4.1. Also assumed for the FSS system is a noise temperature of 1 000 k for the FSS satellite.

TABLE 10-71 FSS system technical characteristics Satellite Downlink e.i.r.p. spectral –20 density (dBW/Hz) Earth Station Antenna size (m) 0.6 1.3 2.8 6 9.1 Transmission Types VSAT VSAT, P-P VSAT, P-P WB, P-P WB, P-P Typical gain (dBi) 37.2 43.9 50.5 57.2 60.5 PSD at antenna port (dBW/Hz) –42 to –59 –42 to –60 –42 to –60 –49 to –60 –49 to –60

10.2.5.3 Interference criteria a) SRS protection criteria The SRS protection criteria are given in Recommendations ITU-R SA.1155 and ITU-R SA.609. However, for the purpose of this study despite the fact that SRS allocation is a secondary allocation in this band if the frequency band is to be considered as shared by both FSS and DRS with equal

328 Rep. ITU-R S.2365-0 status, then FSS could be treated as a Category 2 type of interference and the interference from other SRS sources as a Category 1 type of interference as defined in Recommendation ITU-R SA.1743. Although Recommendation ITU-R SA.1743 does not give an exact apportionment for Category 1 and 2, if a method similar to the one done in Recommendation ITU-R F.1094 is used, then the apportionment for Category 2 interference is 10% of the total interference. Using this approach of apportioning the interference allocation given in Recommendation ITU-R SA.1743 onto the total aggregate interference allowed under SA.609/SA.1155, the interference criteria would be: Io/No criterion = –16 dB for 0.1 % time for DRS E-s, s-E cases Io/No criterion = –20 dB for 0.1 % time for DRS s-s cases b) FSS protection criteria Based on recommends 3 of Rec. ITU-R S.1323, for an FSS GSO network the internetwork interference caused by the earth and space station emissions of all other satellite networks operating in the same frequency band, should be responsible for at most 10% of the time allowance for the BER (or C/N value) specified in the short-term performance objectives of the desired network and corresponding to the shortest percentage of time (lowest C/N value). The FSS protection criteria are given in Recommendation ITU-R S.1432. a) that error performance degradation due to interference at frequencies below 30 GHz should be allotted portions of the aggregate interference budget of 32% or 27% of the clear-sky satellite system noise in the following way: b) 25% for other FSS systems for victim systems not practicing frequency re-use c) 20% for other FSS systems for victim systems practicing frequency re-use d) 6% for other systems having co-primary status e) 1% for all other sources of interference For the purpose of the study, if SRS interference into FSS is treated as having the same status, the Io/No criterion that can be used for FSS is: 1) –12.2 dB (which corresponds to 6%), from Recommendation ITU-R S.1432; and 2) 10% of time, from Recommendation ITU-R S.1323.

10.2.5.4 Assumptions used in the analysis Dynamic simulations were carried out in all cases involving interference into SRS satellites from FSS uplinks. The variable aspect of the simulation is the orbital separation of the SRS and FSS satellites along with the following assumptions: 1) A DRS satellite at 49W is assumed. The International Space Station (ISS) is used as a DRS user satellite. 2) A common service area for SRS and FSS earth stations is assumed for worst case analysis. For the purpose of this analysis, the earth stations are assumed to be collocated, that is, within the 1 dB receive contour of the victim satellite. 3) FSS uplinks from their earth stations are assumed to be accessing GSO satellites in a 60 degrees GSO arc around the DRS satellite with 3 degree spacing. 4) The minimum orbital separation between SRS and FSS GSO satellite is assumed to be 1 degree. 5) The FSS ES antenna sizes ranging from 60 cm to 2.8 m as shown in Table 10-71 are used in the analysis. These are taken from Table 4-1 of this Report. Note that using an antenna larger than 2.4 m will not change the results, as the antenna side lobes would not be further narrowed. Rep. ITU-R S.2365-0 329

6) Interference from FSS uplinks and downlinks into DRS receivers at GSO location in DRS uplinks and DRS return links are computed for different GSO orbital separations between FSS and DRS satellites. The FSS ES are assumed at satellite beam centers considered at the GSO longitude and at latitudes equal to 0 deg, 30 deg and 60 deg. The closest FSS satellite is assumed to be at least 1 degree away from the DRS satellite. All FSS uplink ES in each simulation have the same antenna size and PSD. Multiple results are provided each using a different set of assumed FSS ES antenna size and PSD values ranging between –42 and −60 dBW/Hz. For Case 3 and Case 4 analysis of interference from FSS downlinks, the maximum downlink e.i.r.p. density is –20 dBW/Hz and the FSS satellite antenna gain values of 20 dB and 30 dB are assumed. 7) The FSS power spectral density is assumed to apply for carriers of all bandwidths. SRS and FSS use carriers of different bandwidths and since SRS carriers can be of bandwidth less than the FSS carriers, either single carrier or multicarrier mode, loaded in the transponder, the FSS power density is assumed uniform inside SRS bandwidth. This allows the calculation of Io/No without any bandwidth factor. 8) SRS transmissions occur when the ground station is visible to the SRS satellite. 9) For computing interference from DRS into FSS systems, FSS uplinks are considered for a 60 cm antenna using an uplink PSD of –50 dBW/Hz. However, if the FSS uplinks use alternative values of low PSD, then a detailed C/I analysis is necessary to study the compatibility issues.

10.2.5.5 Analysis Results Static analysis is used when considering SRS uplinks and downlinks and dynamic simulation is used when considering intersatellite links. Dynamic simulation is carried out assuming the FSS satellite beam gain of 20 dB and 30 dB and an uplink power spectral density ranging between –42 to −60 dBW/Hz at the input of a 60 cm to 2.8m FSS earth station antenna and a downlink e.i.r.p. density of –20 dBW/Hz. Earth stations of size larger than 2m would cause the same levels of interference because of the common off-axis pattern. One FSS earth station per FSS satellite is assumed to use the bandwidth used by SRS carriers. The FSS earth stations are assumed at different latitudes (0 deg, 30 deg and 60 deg) and GSO longitudes. Case 1: Interference between DRS uplinks and FSS uplinks a) The interference from FSS uplinks into DRS feeder uplinks is computed considering different uplink PSDS (–42, –50 and –60 dBW/Hz) into an uplink FSS earth station assumed to be collocated with DRS uplink station. The results of interference for varying orbital separation are shown in Fig. 10-67. Even when a low PSD of ‒60 dBW/Hz is used by an FSS earth station, when the earth stations are collocated, the Io/No into DRS uplinks is –14 dB for an orbital separation of 4 degrees. Beam separation advantage can reduce the orbital separation requirements. Coordination is necessary for compatibility.

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FIGURE 10-67 Interference (Io/No dB, 0.1% time) from FSS uplinks into DRS feeder uplinks (ES Collocated case, no contour advantage assumed)

b) The results of interference from DRS feeder uplinks into FSS uplinks with collocated earth stations for varying orbital separation are shown in Fig. 10-68. The interference (Io/No, dB) is –9 dB for 1 deg separation. If the FSS satellite beam gain is less than 30 dB, or if the DRS earth station is not near the beam center of the FSS beam, or if the FSS uplink earth station antenna size is larger than 60 cm, the interference reduces accordingly. Coordination is necessary for compatibility.

FIGURE 10-68 Interference (Io/No dB, 10% time) from DRS feeder uplinks into FSS uplinks (Collocated case; No contour advantage assumed)

Case 2: Interference between DRS return links and FSS uplinks a) The results of interference from FSS uplinks into DRS return links for varying orbital separation are shown in Fig. 10-69. The interference from FSS uplinks into DRS return links is computed considering different uplink PSDs (–42, –50 and –60 dBW/Hz) into an uplink FSS earth station assumed at different locations with latitudes 0 to 60 degrees and with FSS GSO longitudes. FSS earth stations with size more than 2 m have the same off-axis pattern Rep. ITU-R S.2365-0 331

and so cause similar interference levels. It may be noted that FSS earth station antennas at higher latitudes cause large interference compared to those at lower latitudes even after assuming very low PSDs. Even when a low PSD of –60 dBW/Hz is used by an FSS earth station at 60 deg latitudes, the Io/No into DRS return links is –2 dB for an orbital separation of 3 degrees. The actual interference excess and compatibility between FSS uplinks and DRS return links will depend on the percentage allocation for FSS interference as well as the assumptions for the FSS earth stations.

FIGURE 10-69A Interference (Io/No dB, 0.1% time) from FSS uplinks into DRS return links (FSS ES at 0 to 30 deg Latitude and GSO Longitude)

FIGURE 10-69B Interference (Io/No dB, 0.1% time) from FSS uplinks into DRS return links (FSS ES at 60 deg Latitude and GSO Longitude)

b) The results of interference from DRS return links into FSS uplinks for varying orbital separation and FSS satellite gains are shown in Fig. 10-70. The results show that this interference is less than the criterion even for an orbital separation of 1 degree.

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FIGURE 10-70 Interference (Io/No dB, 10% time) from DRS return links into FSS uplinks

Case 3: Interference between DRS uplink and FSS downlinks a) The interference from FSS downlinks into DRS feeder uplinks is computed considering the downlink FSS Earth station at different latitudes (0 degrees, 30 degrees, 60 degrees) and at FSS GSO longitudes. The FSS satellite gains assumed are 20 dB and 30 dB and the maximum downlink e.i.r.p. density is assumed as −20 dBW/Hz. This case represents a reverse band scenario. The results of interference for varying orbital separation are and FSS satellite gains shown in Fig. 10-71. Co frequency compatibility may be possible with a minimum orbital separation of 1 to 2 degrees.

FIGURE 10-71 Interference (Io/No dB, 0.1% time) from FSS downlinks into DRS feeder uplinks FSS Earth Station Latitude = 0, 30 deg, 60 deg; Max e.i.r.p. density=−20 dBW/Hz

b) There could be interference from DRS feeder uplinks into FSS down through a reverse band scenario which requires a minimum coordination distance between DRS feeder uplink stations and FSS downlink earth station. Further analysis is needed to compute these distances, which will depend on the terrain of the earth station locations. Rep. ITU-R S.2365-0 333

Case 4: Interference between DRS Return links and FSS downlinks a) The interference from FSS downlinks into DRS return links is computed considering the downlink FSS Earth station at different latitudes (0 deg, 30 deg, 60 deg) and at FSS GSO longitudes. The FSS satellite gains assumed are 20 dB and 30 dB and the maximum downlink e.i.r.p. density assumed is –20 dBW/Hz. The interference from FSS downlinks into DRS return links represents a reverse band scenario. The results of interference for varying orbital separation and different satellite gains are shown in Fig. 10-72. Co frequency compatibility may be possible with a minimum orbital separation of 1 to 2 degrees.

FIGURE 10-72 Interference (Io/No dB, 0.1% time) from FSS downlinks into TDRS feeder uplinks FSS Earth Station Latitude = 0, 30 deg, 60 deg; Max e.i.r.p. density=-20 dBW/Hz

b) The interference from DRS return links into FSS downlinks will be low because of the trajectory of the DRS user satellite. Interference analysis shows that the interference (Io/No,dB) into FSS downlinks is less than –30 dB.

10.2.5.6 Summary and Conclusion An analysis has been performed to assess the potential for interference between the DRS systems and potential FSS systems in the 14.5-14.8 GHz band. Static analysis is used when analysing compatibility between FSS and SRS uplinks/downlinks and dynamic simulation is used when considering SRS inter-satellite links. Dynamic simulation is carried out assuming the FSS satellite beam gain of 20 dB and 30 dB and an uplink power spectral density ranging between –42 to −60 dBW/Hz at the input of a 60 cm to 2.8m FSS earth station antenna and a downlink e.i.r.p. density of –20 dBW/Hz. Earth station sizes larger than 2.0 m would cause the same levels of interference because of the common off-axis pattern. One FSS earth station per FSS satellite is assumed to use the bandwidth used by SRS carriers. The FSS earth stations are assumed at different latitudes (0 deg, 30 deg and 60 deg) and GSO longitudes. The interference criteria used for SRS and FSS systems to assess the excess interference levels are derived from many ITU Recommendations as shown below: − SRS: The protection criterion is derived using the following Recommendations ITU-R SA.609, SA.1155 and SA.1743 using the methodology given in F.1094. − FSS: The protection criterion is derived using the following Recommendations ITU-R S.1432 and S.1323. The results of the interference analysis considering the same status for SRS and FSS are summarized in Table 10-72.

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TABLE 10-72 Summary of results of interference between DRS systems and proposed FSS Allocations in the 14.5-14.8 GHz band Possible to establish compatibility between SRS and FSS for co-frequency operations? New FSS Frequency FSS interference SRS interference Case SRS (DRS) links allocation band (GHz) into SRS into FSS DRS forward link 1 Yes* Yes* FSS uplink (uplink) (AI 1.6.1) DRS return inter- 2 Yes* Yes 14.50-14.80 orbit link FSS 3 DRS uplink Yes* Yes* downlink DRS return inter- 4 Yes* Yes (AI 1.6.1) orbit link * Coordination between SRS and FSS feasible using measures like: satellite orbital separation, beam separation, ES separation, etc.

Based on the summary Table above, the following can be observed for 14.5-14.8 GHz, FSS uplinks and downlinks: – Case 1: The mutual interference between DRS uplinks and FSS uplinks would exceed the protection criterion, assuming worst case condition like the FSS earth station being collocated with the DRS uplink station. However, coordination measures like increasing the minimum orbital separation between the FSS and DRS GSO satellites, beam separation advantage for earth station locations and possibly other measures could considerably reduce the interference. It is a typical GSO-GSO coordination which could be easily solved by bilateral coordination (i.e. coordination under RR 9.7). – Case 2: Considering similar DRS parameters as used today in the band above 14.8 GHz, DRS return links would receive interference from FSS uplinks higher than the desired protection criterion co-frequency situations assuming worst case conditions. However, as the current DRS return links are using the band above 14.8 GHz, the band 14.5-14.8 GHz may be available for coordination between SRS and FSS under RR 9.7. – Case 3: The mutual interference between DRS uplinks and FSS downlinks represent a reverse band scenario and mutual compatibility can be established by using coordination measures like minimum orbital separation and earth station contour distance, etc. It is a typical coordination between two Earth stations transmitting in opposite direction (i.e. coordination under RR 9.17A). – Case 4: The mutual interference between DRS return links and FSS downlinks represent another reverse band scenario and mutual compatibility can be established by using coordination measures like minimum orbital separation, etc. Coordination will be performed under RR 9.7. Assuming that the SRS DRS return links are restricted in bands above 14.8 GHz, it can be summarized that the compatibility between FSS (E-s and s-E) links and SRS in the band 14.5-14.8 GHz, considering the same status for SRS and FSS, is achievable with coordination measures. Rep. ITU-R S.2365-0 335

10.2.6 FSS (E-s) and radio astronomy In accordance with Table 2 of Annex 1 to Recommendation ITU-R RA.769 the threshold level of interference detrimental to radio astronomy spectral-line observations in the frequency band 14.47-14.5 GHz is –214 dBW in 150 kHz which corresponds to PSD level of –265.7 dBW/Hz. Mitigation techniques that may be used to protect RAS from unwanted emissions of FSS systems (including RF filtering to reduce unwanted emissions in the spurious domain) are described in Recommendation ITU-R SM.1542. The minimum required value of basic losses for protection of the RAS from FSS ES unwanted emissions can be estimated by the following equation:

Lb( p%) = Punwanted  GFSS (t) – (ΔPH – GRAS (r)) where: Punwanted : The power of unwanted emissions caused by FSS ES transmitter in the RAS band, dBW

GFSS (t) : FSS ES antenna gain in the direction of RAS station (dBi)

GRAS (r): Radio telescope antenna side lobe gain in accordance with Recommendation ITU-R RA.769 (dBi)

ΔPH : Threshold interference power level at the input of the RAS receiver in accordance with Recommendation ITU-R RA.769 (dBW) t : angle between the direction of main emission and direction to the victim receiver (deg.) r : angle between the main beam of RAS station antenna and interference source (deg.) Lb( p%): minimum required value of basic losses not exceeding at p% of time, dB. The protection distance is defined based on the basic propagation losses described by the methodology given in Recommendation ITU-R P.452. The estimation of the minimum required values of basic losses and the required protection distances were carried out under the following assumptions. FSS ES with antenna diameter Dant = 1.2 m and larger; FSS ES antenna pattern is described in Recommendation ITU-R S.580, the minimum elevation angle of FSS ES antenna is 10 degrees. The power spectral density of FSS ES in the operating frequency band is –55 dBW/Hz. The RAS station antenna side lobe level is 0 dBi (Recommendation ITU-R RA.769). To define the protection distances depending on the required basic propagation loss estimated by the methodology given in Recommendation ITU-R P.452-14 the following assumptions were taken: the average vertical gradient of radiowave refraction index of the lower atmosphere ΔN = 50, surface refractivity N0 = 329, average frequency 14.488 GHz, wavelength λ = 2.07 cm, the propagation model in A2 zone (all land, other than coastal and shore areas) is used, FSS transmitting ES antenna center height hFSS = 5 m, RAS station antenna center height above the ground level hRAS = 40…120 m. The estimations were carried out for smooth surface excluding terrain of the interfering signal propagation path. The estimation of the required basic losses in accordance with equation above is presented in Table 10-73.

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TABLE 10-73 FSS ES PSD (dB(W/Hz)) –55 Attenuation (dB) below the power supplied to the antenna transmission line 60 Unwanted emission PSD in the RAS band (dB(W/Hz)) –115 FSS antenna gain in the RAS direction (dBi) 4 The gain for the RAS antenna side-lobe level (dBi) 0 Threshold level of interference detrimental to radio astronomy spectral-line observations –265.7 (dBW/Hz) Minimum required value of basic losses (dB) –154.7

The calculation results of the protection distances depending on the minimum required basic propagation losses for RAS station antenna heights of 40 m, 80 m and 120 m are shown in Table 10-74.

TABLE 10-74 RAS antenna height, m 40 80 120 Protection distance, km 34 43 51

As it is shown in Table 10-74 the separation distance for protection of RAS stations in the frequency band 14.47-14.5 GHz from the unwanted emissions of FSS ES operating in the frequency band 14.5-14.75 GHz is from 34 km to 51 km depending on the RAS station antenna height. These values do not take into account the propagation path terrain of interfering signal and could be reduced taking into account diffraction and reflection due to natural obstacles. Thus the separation distances from several km to several tens of km are sufficient for protection of the RAS stations making spectral-line observations in the frequency band 14.47-14.5 GHz on a secondary basis from the unwanted emissions impact of FSS ES operating in the frequency band 14.5-14.75 GHz. Moreover it should be emphasized that the frequency band 14.47-14.5 GHz, which is allocated to the RAS on a secondary basis, is currently allocated to FSS (E-s) on a primary basis and is already used by FSS ES. Obviously, the compatibility in the out-of-band and spurious domains between RAS in the band 14.47-14.5 GHz and FSS (E-s) in the band 14.5-14.75 GHz will also be ensured as the performed studies have shown.

10.2.7 FSS (s-E) and MS/AMS 10.2.7.1 FSS (s-E) interference into MS The MS station characteristics in the frequency band 14.5-15.35 GHz are given in Annex 18 to WP 5A Chairman’s Report (Document 5A/198). FSS satellite characteristics contained in § 4 of this Report. The MS station characteristics taken into account in the static analysis and calculated permissible interfering signal power levels are given in Table 10-75.

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TABLE 10-75

MS system System 1 System 2 System 3 System 4 System 5 System 6 Frequency range, GHz 14.5-15.35 14.5-15.35 14.5-15.35 14.5-15.0 14.5-15.3 14.6-15.35 Antenna polarization RHC Linear Linear Linear H/V LHC Antenna beam, degrees 10 × 15 60 × 40 3 × 3 2.1 × 2.1 2.2 × 2.2 1.9 × 1.9 Antenna gain, dBi 18 4 23 25 24 28 Antenna 1st side lobe level, 8 0 10 12 11 N/A dBi Min. sensitivity, dBm –93 –98 –105 –97 –106 –94 Emission 50M0G1D 18M5F9W 4M60F9W 20M0G7W 2M46G1D 40M0G7W Receiver IF –3 dB 55 21 4 23 3 35 bandwidth, MHz Receiver noise figure, dB 4 3 3 4 4 5 Interference criterion I/N, dB –6 –6 –6 –6 –6 –6 Receiver noise level, dBW –122.6 –127.8 –135.0 –126.4 –135.2 –123.6 Interference permissible level in receiver bandwidth, –128.6 –133.8 –141.0 –132.4 –141.2 –129.6 dBW

The calculation results of the interference level at the MS station receiver input are given in Table 10-76. The calculations take into account interfering signal on the main and first side lobe beam of the MS station antenna pattern. The applied criteria of I/N = –6 dB is valid for the aggregate interference from all FSS satellite to GSO. The criteria for single interference will be more stringent.

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TABLE 10-76

FSS downlink e.i.r.p. density, 40 dBW/MHz Free space path loss, dB 208.4 Signal power density to the Earth, -168.4 dBW/MHz MS system System 1 System 2 System 3 System 4 System 5 System 6 MAIN BEAM Main beam up to, deg 7.5 20 1.5 1.05 1.1 0.95 Antenna main beam gain, dBi 18 4 23 25 24 28 Antenna polarization RHC Linear Linear Linear H/V LHC Polarization losses (FSS Liner), 1.5 0 0 0 0 1.5 dB Interference density, dBW/MHz –151.9 –164.4 –145.4 –143.4 –144.4 –141.9 Interference density in receiver –134.5 –151.2 –139.4 –129.8 –139.6 –126.5 bandwidth, dBW Margin, dB 5.9 17.4 –1.6 –2.6 –1.6 –3.1 1ST SIDE LOBE Free space path loss, dB 207 Signal power density to the Earth, -167 dBW/MHz Antenna 1st side lobe level, dBi 8 0 10 12 11 N/A Antenna polarization RHC Linear Linear Linear H/V LHC Polarization losses (FSS Liner), 1.5 0 0 0 0 1.5 dB Interference density, dBW/MHz –160.5 –167 –157 –155 –156 N/A Interference density in receiver –143.1 –153.8 –151.0 –141.4 –151.2 N/A bandwidth, dBW Margin, dB 14.5 20.0 10.0 9.0 10.0 N/A

10.2.7.2 AMS aircraft interference into FSS Earth station receiver If the 14.5-15.35 GHz band is used for FSS downlinks in Region 1, then existing AMS systems may cause interference into FSS earth station receivers. Figure 10-73A is the plot of the interference produced by an AMS aircraft into a FSS earth station receiver when the FSS receiver is located at four different orientations North West, North East, South West and South East with respect to the AMS ground station. The AMS ground station is assumed to be located 130 km from the FSS receiver. The AMS aircraft is the moving object in a grid-line format. The interference-to-noise (I/N) of AMS aircraft into FSS FSS receiver is calculated at every grid point. Figure 10-73B is the union of the four plots shown in Fig. 10-73A which accounts for the FSS at four different orientations with respect to AMS ground station. Figure 10-73C is the union of the I/N produced by an AMS aircraft into the FSS receiver which accounts for the FSS receiver locates at all possible orientations with the respect to the AMS ground station. The FSS receiver system noise temperature in Figs 10-73A, 10-73B and 10-73C is 200 K.

Rep. ITU-R S.2365-0 339

FIGURE 10-73A I/N plot of AMS aircraft interference into a FSS Receiver at four different orientations with respect to FSS

FIGURE 10-73B I/N plot of union of four plots in Fig. 10-73A AMS aircraft interference into a FSS Receiver

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FIGURE 10-73C I/N plot of AMS aircraft interference into a FSS Receiver at all possible orientations with respect to FSS

A FSS I/N threshold of –10 dB that can be exceeded for 20% of any month is assumed based on Recommendation ITU-R S.1432. This threshold is exceeded at distances up to 572 km, depending on azimuth and elevation of the aircraft.

10.2.7.3 FSS GSO space station interference into AMS aircraft/AMS/MS station receiver Table 10-77 presents the results of link calculations of the estimated I/N that could occur under three cases: FSS GSO interference into AMS aircraft; FSS GSO interference into AMS station; FSS GSO interference into MS station. Each case assumes the satellite e.i.r.p. density of –20 dBW/Hz as specified in Table 10-44 above. Rep. ITU-R S.2365-0 341

TABLE 10-77 Interference from GSO FSS satellite into AMS aircraft/AMS station/ MS station receiver

In three cases, the –6 dB I/N threshold is exceeded when the AMS aircraft/AMS station/MS station main beam intersects the GSO. In each case, the interference from FSS GSO into AMS aircraft, AMS station receiver and MS receiver exceeds by 4.96 dB, 21.96 dB and 2.96 dB respectively. Table 10-78 shows the allowable GSO satellite pfd into AMS aircraft/AMS station for FSS (space-to- Earth) operations in the 14.5-15.35 GHz.

TABLE 10-78 Summary results of AMS aircraft/AMS station/MS sharing with FSS downlinks

10.2.7.4 Summary of studies With respect to a potential allocation to the FSS (space-to-Earth) in Region 1, the analysis in this scenario shows that in order to protect FSS receiving earth stations in the 14.5-15.35 GHz band from AMS system transmissions, a separation distance of up to 572 km (not accounting for terrain obstruction) describes an area around a FSS receiving earth station receiver where the protection criteria is exceeded. In addition, since the main beams of such AMS systems/MS systems may point at the GSO, AMS aircraft/AMS station/MS system receivers may be subject to unacceptable levels of interference from FSS GSO over periods of time. This study determined that a pfd of –128 dBW/m2-MHz, −145 dBW/m2-MHz and –126 dBW/m2-MHz would protect AMS aircraft, AMS station and MS system receivers respectively, which is more restrictive than pfd limits applicable in nearby bands. This should be taken into account in developing any methods. The results of the performed static analysis of the compatibility between FSS (s-E) and MS in the frequency band 14.5-15.35 GHz show that the EMC for systems 1 and 2 is feasible for the worst interference scenario (interference impact from the FSS satellite on the main lobe of the MS station

342 Rep. ITU-R S.2365-0 antenna pattern). The excess of the permissible interference level at the receiver input of Systems 3, 4, 5, 6 is 1.6 …3.1 dB. In case interfering signal falls on the first side lobe of the MS station antenna pattern of all 6 types the EMC is feasible and interference margin is from 10 to 20 dB. The dynamical analysis is required for more detailed EMC assessment for the considered stations. One study demonstrated that FSS GSO may require FSS operations at PFD levels of −128 dBW/m2-MHz, –145 dBW/m2-MHz and –126 dBW/m2-MHz in order to protect AMS aircraft, AMS station and MS system receivers, respectively.

10.2.8 FSS (s-E) and FS 10.2.8.1 Interference from FS to FSS (s-E) The studies contained in § 11.2.8.1 concerning the sharing between FSS (space-to-Earth) and FS in the frequency band of 14.8-15.35 GHz could be also applied to the frequency band 14.5-14.8 GHz.

10.2.8.2 Interference from FSS (s-E) to FS 10.2.8.2.1 Study#1 Characteristics of FS stations in the frequency band considered are specified in Recommendation ITU-R F.758-5. Taking into account the criteria I/N = –10 dB, the maximum allowable power density of the long-term aggregate interference at the FS station input is –146 dB (W/MHz). This study considered two types of FS stations having gain of 37 dBi (Type 1 FS station) and that of 31.9 dBi (Type 2 FS station). Estimated masks of acceptable aggregate pfd from GSO FSS space stations in the direction of FS station are shown in Fig. 10-74. They were calculated using maximum acceptable power density of −146 dB(W/MHz) for long-term aggregate interference at FS station, mathematical description of FS station receiving antenna pattern (Recommendation ITU-R F.1245). Rep. ITU-R S.2365-0 343

FIGURE 10-74 Masks for acceptable aggregate pfd

-80

-90

-100

-110

MHz

1 1

) ) 2

m -120

(

dB , , -130

PFD Acceptable aggregate PFD from FSS to FS type 1 station

Acceptable aggregate PFD from FSS to FS type 2 station -140

-150

-160 0 20 40 60 80 Angle of arrival, deg.

The results of studies in compatibility of FSS (space-to-Earth) and FS provided for defining the masks for acceptable pfd from GSO FSS space stations in the direction to a FS station. Figure 10-74 shows that limitation of pfd would be between (–115 dB(W/m2·MHz)) and (–90 dB(W/m2·MHz)) for interfering signal arrival angles from 5º to 90º. The above limitations would be more stringent for arrival angles below 5º where “main lobe-to-main lobe” interference scenario is exist.

10.2.8.2.2 Study#2 The studies contained in § 11.2.8.2 concerning the sharing between FSS (space-to-Earth) and FS in the frequency band of 14.8-15.35 GHz could be also applied to the frequency band 14.5-14.8 GHz.

10.3 Summary compatibility of studies between FSS (Earth-to-space) and existing services in the band 14.5-14.8 GHz 10.3.1 With respect to the BSS feeder-links − Sharing is compatible between the FSS (Earth-to-space) and BSS feeder-links. In order to ensure the protection and integrity of the Plan and List assignments, regulatory and technical provisions are needed to allow for the coexistence of current and future BSS feeder-link assignments and future FSS (Earth-to-space) assignments.

10.3.2 With respect to the fixed service − Sharing is feasible with the fixed service and coordination is currently handled by the provisions and methods contained in RR Appendix 7.

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10.3.3 With respect to the aeronautical mobile service Eight studies were performed and the results from all six show that interference from the FSS (Earth- to-space) into the AMS exceed the protection criterion depending on the distance between the AMS receiving station and the FSS earth station. Nevertheless, the AMS (aircraft and land) stations are mobile in nature; therefore, setting a minimum separation distance with respect to a transmitting FSS earth station is not possible in practice. − Study #1 (static analysis) showed that VSAT FSS earth stations exceed the AMS protection criterion at distances up to 575 km when the airborne station operates at 19 km in altitude − Study #1A (static analysis) showed that the percentage of total square area where the AMS protection criteria is exceeded ranges from 475 km² or 0.05% to 7 000 km² or 5.57% of the area considered in this study (see Fig. 10-27) when the FSS earth station is located at distance from 550 km, 1.10% at 400 km and 0.15% to 200 km with respect to the AMS ground station − Study #2 (dynamic analysis) showed that the percentages of interference occurring from a VSAT FSS earth station into an AMS airborne station operating at 19 km and 2.4 km were 0.9% and 7.3% respectively − Study #3 (static analysis) showed that using characteristics from Appendix 30A feeder-links currently allocated in this band exceed the AMS protection criteria at distances of 400 – 500 km when the AMS airborne station operates at 19 km in altitude − Study #4 (dynamic analysis) showed that FSS earth station antenna size is irrelevant to the occurrence of interference that exceeds the I/N protection criterion of the AMS. The percentage of exceeding the protection criterion of an AMS station operating at 19 km was approximately 4% when a separation distance of 250 km is considered between the AMS ground station and FSS earth station − Study #4A (dynamic analysis) showed that the interference relationship between the FSS earth station with the AMS airborne station is dependent on (1) the distance between the FSS earth station and AMS ground station and (2) the altitude of the AMS airborne station where the likelihood of interference occurring from an FSS earth station into an AMS airborne station operating at 19 km was 0% when a separation distance of 482 km is considered between the AMS ground station and FSS earth station − Study #5 (dynamic analysis) showed that considering an AMS aircraft operating at altitudes between 1000 m and 20000 m, the probability that the interference from an FSS earth station exceeds the AMS protection criterion is as follows : • Between 24% and 32% for an AMS aircraft station operating between 0 to 200 km from the FSS earth station. • Up to 10% for an AMS aircraft station operating between 0 to 450 km from the FSS earth station. − Study #6 (dynamic and operational analysis) showed that a single FSS earth station generates a zone where interference exceeds the protection criterion extending up to 61.7 km in length and 26.7 km in width (with an associated probability varying from 1% to 100%) aligned with the main-lobe of the FSS earth station. Considering various aircraft speeds (up to 200 m/s) and altitudes (3 000 m to 10 000 m), when the I/N protection criterion is exceeded for AMS systems, the link recovery procedure could imply a service interruption duration up to several minutes with unacceptable operational impacts on AMS. Table 10-79 summarizes Studies #1 through #6:

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TABLE 10-79

Assumptions for assessment of the probability of exceeding Assumptions Results AMS aircraft protection criteria Results

Separation distance between FSS earth station and AMS victim Probability of exceeding AMS protection AMS aircraft station Distance between FSS E/S criterion maximum (km) Study antenna FSS PSD Propaga- Study Type antenna Number diameter, (dBW/Hz) tion model(1) gain max gain (dBi) AMS ground AMS victim Aircraft Aircraft station and aircraft and Aircraft altitude Aircraft altitude altitude altitude FSS earth FSS earth 2400 m 19 000 m 2 400 m 19 000 m station in km station in km 1.2 m, 27 (AMS −42, −50, Rec ITU-R 1 Static 152-184 470-575 N/A N/A N/A N/A 42.7 dBi system 2) −55, −59 P.528 1.2 m, 1A Dynamic 27 -50 Free Space See 10-23 42.7 dBi 0.75 m, N/A 225 km – 7.3% 0.9% 2 Dynamic N/A −57 N/A N/A N/A 39.3 dBi 615 km (for 225 km) (for 615 km) 6 m, Rec ITU-R 3 Static 24 −49.3, −57 150 500, 400 N/A N/A N/A N/A 57.4 dBi P.528 (1.2, 2.4, 20-250 N/A 6) m, 0.9% (for 250 km) 3.7% (250 km)-50% 4 Dynamic N/A −50 Free space N/A N/A (42.7, 49.4, 93.6% (for 20 km) (for 20 km) 57.4) dBi (1.2, 2.4, 20-500 N/A 6) m, 0% (for 500 km) 4A Dynamic N/A −50 Free space 180 482 (42.7, 49.4, 39% (for 20 km) 57.4) dBi 2.4 m, 6 m, N/A(3) 83 to 450 3 (AMS Rec ITU-R 5% (for 450 km) 5 Dynamic 49.4 dBi, −49 83 to 151(4) 87 to 451(4) system 6) P.528 100% (for 83 km)(2) 57.4 dBi

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TABLE 10-79 (end)

Assumptions for assessment of the probability of exceeding Assumptions Results AMS aircraft protection criteria Results

Separation distance between FSS earth station and AMS victim Probability of exceeding AMS protection AMS aircraft station Distance between FSS E/S criterion maximum (km) Study antenna FSS PSD Propaga- Study Type antenna Number diameter, (dBW/Hz) tion model(1) gain max gain (dBi) AMS ground AMS victim Aircraft Aircraft station and aircraft and Aircraft altitude Aircraft altitude altitude altitude FSS earth FSS earth 2400 m 19 000 m 2 400 m 19 000 m station in km station in km 2.4 m, 6 m, Dynamic/ 3 (AMS Rec ITU-R 6 49.1 dBi, −50 See Table 10-58, Table 10-59 and Table 10-60 Operational system 6) P.528 57.1 dBi (1) In the calculations, when the propagation model defined by Recommendation ITU-R P.528 is used, the value of the basic transmission loss is the value not exceeded for 1% of the time (2) When the FSS earth station and AMS aircraft station separation distance vary from 0 to 450 km and the AMS aircraft station altitude ranges from 1 and 20 km. There is no influence of the AMS ground station position. The closer the AMS aircraft station from the FSS earth station, the higher the likelihood of harmful interference into the AMS aircraft station i.e. 100% for distances below 83 km distance. (3) There is no influence of the AMS ground station position due to the ubiquitous position of the aircraft. (4) The distance range limits correspond to the worst and the best cases of interference (AMS aircraft in the FSS main beam or outside the FSS main beam).

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10.3.4 With respect to the land mobile service (see § 10.2.4) − Study #1 (static analysis) showed that VSAT FSS earth stations exceed the MS protection criterion at distances of 46 km when the land mobile station operates at 13 m above the terrain. − Study #2 (dynamic analysis) showed that the percentage of interference occurring from a VSAT FSS earth station into an MS mobile station operating 13 m above the terrain was 15%. − Study #3 (dynamic analysis) showed that an aggregate analysis of FSS earth stations interfering into MS mobile station operating at 13 m above the terrain exceeds the protection criteria by 0.3% of the time.

10.3.5 With respect to the space research − Sharing with the space research is feasible under the conditions that the space research service in the 14.5-14.8 GHz be used for Earth-to-space transmissions to geostationary orbiting satellites in the space research service.

10.3.6 With respect to the radioastronomy service: − Sharing is compatible between FSS (Earth-to-space) unwanted emissions and radioastronomy service, opertating in the band 14.47-14.5 GHz. The protection criteria of RAS stations under FSS unwanted emissions impact are met without any limitations.

11 Frequency band 14.8-15.35 GHz The allocations of this band in RR Article 5 are as shown below.

TABLE 11-1 Excerpts from Article 5 of the Radio Regulations on allocation to services in 14.8-15.35 GHz

Allocation to services Region 1 Region 2 Region 3 14.8-15.35 FIXED MOBILE Space research 5.339

5.339 The bands 1 370-1 400 MHz, 2 640-2 655 MHz, 4 950-4 990 MHz and 15.20-15.35 GHz are also allocated to the space research (passive) and Earth exploration-satellite (passive) services on a secondary basis. The frequencies within the 14.8-15.3 GHz band are allocated by some administrations for aeronautical mobile service on a primary basis. There have been no known compatibility studies between this service and FSS (Earth-to-space). It should be noted that although the review of studies performed and the preliminary analyses shown below only focused on the 14.8-15.2 GHz band, the sharing study of FSS (Earth-to-space) with space research (passive) and EESS (passive) as indicated in RR footnote No. 5.339 in the band of 15.2-15.35 GHz has not been performed.

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11.1 Review of Recommendations for the band of 14.8-15.35 GHz A list of relevant Recommendations that may be useful for sharing studies is in Table 11-2.

TABLE 11-2 Summary of relevant Recommendations that may be useful for sharing studies in the band 14.8-15.35 GHz

Service Relevant Recommendation Fixed Recommendation ITU-R F.699 Recommendation ITU-R F.758 Recommendation ITU-R F.1107 Recommendation ITU-R F.1245 Recommendation ITU-R F.1333 Recommendation ITU-R F.1336 Recommendation ITU-R F.1777 Recommendation ITU-R F.636 Recommendation ITU-R F.746 Mobile Recommendation ITU-R M.1824 Earth exploration-satellite Recommendation ITU-R RS.515 (passive) Recommendation ITU-R RS.2017 Radio astronomy Recommendation ITU-R RA.769 (adjacent band) Recommendation ITU-R RA.1513-1 Space research Recommendation ITU-R SA.609 Recommendation ITU-R SA.1019 Recommendation ITU-R SA.1018 Recommendation ITU-R SA.1155 Recommendation ITU-R SA.1414 Recommendation ITU-R SA.1626

11.2 Sharing studies for the band 14.8-15.35 GHz 11.2.1 Preliminary analyses of the band 14.8-15.2 GHz

TABLE 11-3 Comparison of services allocated in the bands 14.5-14.8 GHz and 14.8-15.2 GHz

14.5-14.8 GHz 14.8-15.2 GHz FIXED FIXED MOBILE Identical MOBILE Space research Space research FIXED-SATELLITE (Earth-to-space) 5.510

Table 11-3 shows a comparison of services allocated in the bands 14.5-14.8 GHz and 14.8-15.2 GHz. If the applications and technical characteristics of FS, MS and SRS in the adjacent bands 14.5-14.8 GHz are similar to those in 14.8-15.2 GHz, then the allocation to “FIXED-SATELLITE (Earth-to-space) 5.510” in the 14.5-14.8 GHz band demonstrates the possibility of co-existence of Rep. ITU-R S.2365-0 349 fixed-satellite service (Earth-to-space) with existing services in the band of 14.8-15.2 GHz. Note however that, while the use of the 14.5-14.8 GHz band by the SRS is for DRS feeder links, the 14.8-15.2 GHz band is also used for DRS inter-orbit links, as well as NGSO SRS downlinks, for which the technical characteristics are different. Although the allocation of fixed-satellite service in the 14.5-14.8 GHz band is limited to feeder links for the broadcasting-satellite service (RR Appendix 30A) and is reserved for countries outside Europe, since the technical characteristics of planned and unplanned FSS are very similar following Recommendation ITU-R S.1328-4, sharing of unplanned FSS (Earth-to-space) with existing services in the 14.8-15.2 GHz band may be feasible. For example, sharing with existing services in 14.8-15.2 GHz band may be feasible if unplanned FSS (Earth-to-space) is operating within the envelope similar to those as prescribed in RR Appendix 30A for 14.5-14.8 GHz. The operational limitations in the band of 14.8-15.2 GHz will depend on the results of further sharing studies taking into account the compatibility with existing services in this band.

11.2.2 FSS (E-s) and FS The studies as contained in the section concerning the sharing between FSS (Earth-to-space) and FS in the band of 14.5-14.8 GHz are equally applicable to the 14.8-15.35 GHz band. The slightly higher frequency would lead to marginally shorter coordination distance and required separation distance a quick calculation indicates the improvement is in the order of less than 3 km using the RR AP7 method. Therefore, it is possible to assume the result is the same as those contained the 14.5-14.8 GHz section and readers should refer to that section for additional detail.

11.2.3 FSS (E-s) and AMS and MS Sections 10.2.3 and 10.2.4 contain studies relevant to this frequency band.

11.2.4 FSS (E-s) and Earth exploration-satellite (passive) No sharing studies were submitted to the ITU-R for FSS (s-E) satellite systems and Earth expoloration-satelite (passive) systems in the band 14.8-15.35 GHz.

11.2.5 FSS (E-s) and radio astronomy No sharing studies were submitted to the ITU-R for FSS (E-s) satellite systems and radio astronomy in the band 14.8-15.35 GHz.

11.2.6 FSS (E-s and s-E) and space research 11.2.6.1 SRS characteristics The frequency band 14.8-15.35 GHz is used by SRS DRS systems for return inter–orbit links (NGSO user spacecraft-to-GSO DRS) and forward feeder links (earth stations-to-GSO DRS). Figure 9-9, taken from Recommendation ITU-R SA.1018, shows a hypothetical reference system representing a DRS. The technical characteristics of transmitting earth stations, NGSO space stations and receiving GSO DRS space stations are presented in Recommendation ITU-R SA.1414. The protection criteria for the various links of data relay satellite systems are provided in Recommendation ITU-R SA.1155. ITU-R Space Radiocommunication Stations Data Base (version February 2013) contains information on 146 forward feeder links with the 41 GSO DRS space stations and 97 return inter-orbit links of 9 NGSO space stations that use frequency band 14.8-15.35 GHz for DRS links. The frequency band 14.8-15.35 GHz is also used by SRS systems for high rate data transmit from spacecraft to earth stations. These missions are limited in number with an estimated three to five satellites per year worldwide, and will generally be either in a low-polar orbit or in an equatorial orbit

350 Rep. ITU-R S.2365-0 with some at geostationary altitudes or in the highly elliptical Earth orbit (HEO) and others at the L1 or L2 libration points. Typical characteristics of the GSO, low-orbiting and highly elliptical-orbiting SRS satellites transmitting in the space-to-Earth direction are reflected in the link budgets given in Recommendation ITU-R SA.1626-1. Table 11-4 shows technical and operational parameters of existing and planned HEO NGSO SRS systems..

TABLE 11-4 Technical and operational parameters used by HEO NGSO SRS systems

Parameters HEO NGSO SRS systems HEO Satellite initial orbital parameters 330000/600, 51.4 apogee/perigee (km), inclination (degrees) Necessary Bandwidth, min/max (MHz) 144/208 RF transmit power level, min/max (dBW) 4.8/14.8 Antenna feeder losses, dB 1 Maximum PSD (dBW/Hz) –66.8 Transmitting antenna diameter (m) 1.5 Transmitting antenna gain (dBi) 45.2 Antenna –3 dB beamwidth (degrees) 1 Satellite Antenna pattern S. 672 (Ls –15 dB) Existing receiving Earth stations PUSCHINO (37E37 54N49) Receiving antenna diameter (m) 22 Receiving antenna gain (dBi) 67 Earth Station Antenna Pattern S. 465 Receiving system Noise Temperature (K) 120 Minimal elevation angle (degrees) 10 Aggregate Interference Criteria Rec. SA. 609-2 Aggregate Interference Protection criteria (Io/No, dB) –6 % time for the protection criteria 0.1%

It should be noted that the satellite’s orbit is fluctuating in cycles due to gravitational effect from the Moon, with its apogee changing between 270 000 and 360 000 kilometres, its perigee changing between 600 and 70 000 kilometres, inclination changing between 40 and 70 degrees. For the sake of comprehensive study current orbit parameters of the RadioAstron satellite were also taken into account, as an example of this effect (apogee 280 000 km, perigee 57 000 km, inclination 56.8 degrees).

11.2.6.2 Compatibility studies between FSS (s-E, E-s) and SRS DRS systems The interference analysis given in § 10.2.5 for the band 14.5-14.8 GHz would apply in this section also and the summary and conclusions reached in that section can be extended to the band 14.8-15.35 GHz, except for the case 2 (Compatibility between DRS return links and FSS uplinks). The SRS DRS system characteristics defined in § 10.2.5.1 apply for the band 14.8-15.35 GHz. Rep. ITU-R S.2365-0 351

11.2.6.2.1 FSS characteristics Same as given in § 10.2.5.2.

11.2.6.2.2 Interference criteria Same as given in § 10.2.5.3.

11.2.6.2.3 Assumptions used in the analysis Same as given in § 10.2.5.4.

11.2.6.2.4 Analysis results Same as given in § 10.2.5.5.

11.2.6.2.5 Summary & conclusion An analysis has been performed to assess the potential for interference between the near Earth DRS missions and potential FSS systems in the 14.8-15.35 GHz band. Static analysis is used when analysing compatibility between FSS and SRS uplinks/downlinks and dynamic simulation is used when considering SRS intersatellite links. Dynamic simulation is carried out assuming the FSS satellite beam gain of 20 dB and 30 dB and an uplink power spectral density ranging between –42 to 60 dBW/Hz at the input of a 60 cm to 2.8 m FSS earth station antenna and a downlink e.i.r.p. density of –20 dBW/Hz. Earth station sizes larger than 2.0 m would cause the same levels of interference because of the common off-axis pattern. One FSS earth station per FSS satellite is assumed to use the bandwidth used by SRS carriers. The FSS earth stations are assumed at different latitudes (0 degrees, 30 degrees and 60 degrees) and GSO longitudes. The interference criteria used for SRS and FSS systems to assess the excess interference levels are derived from many ITU Recommendations as shown below: − SRS: The protection criterion is derived using the following Recommendations ITU-R SA.609, SA.1155 and SA.1743. − FSS: The protection criterion is derived using the following Recommendations ITU-R S.1432 and S.1323. The results of the interference analysis considering the same status for SRS and FSS are summarized in Table 11-5.

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TABLE 11-5 Summary of results of interference between DRS systems and proposed FSS allocations in the 14.8-15.35 GHz band

Possible to establish compatibility between SRS and FSS for co-frequency operations? New FSS Frequency FSS interference SRS interference Case SRS (DRS) Links Allocation band (GHz) into SRS into FSS DRS forward 1 feeder link Yes* Yes* FSS uplink (uplink) (AI 1.6.1) DRS return inter- 2 No Yes 14.80-15.35 orbit link FSS 3 DRS uplink Yes* Yes* downlink DRS return inter- 4 Yes* Yes (AI 1.6.1) orbit link * Coordination between SRS and FSS feasible using measures like: satellite orbital separation, beam separation, ES separation, etc.

Based on the summary Table above, the following can be observed for 14.8-15.35 GHz, FSS uplinks/downlinks: – Case 1: The mutual interference between DRS uplinks and FSS uplinks would exceed the protection criterion, assuming worst case condition like the FSS earth station being collocated with the DRS uplink station. However, coordination measures like increasing the minimum orbital separation between the FSS and DRS GSO satellites, beam separation advantage for earth station locations and possibly other measures could considerably reduce the interference. It is a typical GSO-GSO coordination which could be easily solved by bilateral coordination (i.e. coordination under RR 9.7). – Case 2: DRS return links would receive unacceptable interference from FSS uplinks assuming worst case conditions. – Case 3: The mutual interference between DRS uplinks and FSS downlinks represent a reverse band scenario and mutual compatibility can be established by using coordination measures like minimum orbital separation and earth station contour distance, etc. It is a typical coordination between two Earth stations transmitting in opposite direction (i.e. coordination under RR 9.17A). – Case 4: The mutual interference between DRS return links and FSS downlinks represent another reverse band scenario and mutual compatibility can be established by using coordination measures like minimum orbital separation, etc. Coordination will be performed under RR 9.7. Thus, it can be summarized that the compatibility between FSS uplinks (E-s) and SRS in the band 14.8-15.35 GHz, considering the need to provide the continuity of the existing/operational DRS services in the 14.8-15.35 GHz band and assuming the same status for SRS and FSS, would not exist. Rep. ITU-R S.2365-0 353

11.2.6.3 Compatibility studies between GSO FSS systems(s-E) and HEO NGSO SRS systems (s-E) In order to determine potential for interference between the GSO FSS systems and HEO NGSO SRS systems, operating in the same downlink direction, dynamic simulations were conducted for a set of technical and operational parameters of the considered services. Technical and operational parameters of NGSO SRS systems were taken from § 11.2.6.1, Table 11-4.

11.2.6.3.1 FSS characteristics Table 11-6 shows the FSS system parameters, used in the study (based on parameters taken from Table 4-1). System noise temperature of 150 K is assumed for the FSS Earth stations.

TABLE 11-6 FSS system technical characteristics

FSS Satellite Maximal Downlink e.i.r.p. spectral –20 density (dBW/Hz) FSS Earth Stations FSS ES1 FSS ES2 FSS ES3 Antenna size (m) 0.6 1.8 2.4 Efficiency 0.65 Typical gain (dBi) 37.6 47.2 49.7 Off-axis radiation pattern S.1855 S.580 S.580 Main lobe characteristics Rec. ITU-R BO.1213 Minimum elevation angle 10°

11.2.6.3.2 Interference criteria Protection criterion for earth stations in the space research service is given in Recommendation ITU-R SA.609-2. For unmanned missions, the aggregate I0/N0 shall not exceed –6 dB for more than 0.1% of time. For the sake of simplicity, the apportionment approach for the protection criterion is not taken into account in this study, however it should be noted that there might be short-term interference impacts from other SRS applications in the band (DRS systems), as well as terrestrial services, in addition to interference from FSS.

For the FSS earth stations single-entry interference criterion of I0/N0 = –12.2 dB (which corresponds to ΔT/T = 6%, based on Recommendation ITU-R S.1432) is used as a threshold. This value shall not be exceeded for 100% of time.

11.2.6.3.3 Assumptions used in the study Dynamic simulations were carried out during 2 year time period with 10 second time increment, taking into account initial and current orbital parameters of RadioAstron satellite. Following assumptions were made: 1) FSS satellites are located on GSO with 3 degree spacing. 2) Maximal downlink e.i.r.p. spectral density (dBW/Hz) of FSS satellites is –20 dBW/Hz, pfd mask limits to protect terrestrial services, was also taken into account (–132/–122 dB (W/m2 1 MHz) for the corresponding elevation angles).

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3) FSS earth stations are assumed to be collocated with SRS earth station at 37E37 54N49 for the worst case interference scenario (Scenario 1). As an alternative (Scenario 2), FSS earth stations are considered to be located at the Equator. 4) SRS system transmissions occur when the associated earth station is visible to the SRS satellite with a minimum elevation angle of 10 degrees. 5) FSS satellites and NGSO SRS satellite operate at the same carrier frequency, 15.0 GHz. 11.2.6.3.4 Analysis results

The potential for interference (I0/N0 probability curves) from GSO FSS downlinks into NGSO SRS downlinks are shown in Figs 11-1, 11-2 for two different orbit parameters of HEO SRS satellite.

FIGURE 11-1

Interference (I0/N0 probability curves) from GSO FSS downlinks into NGSO SRS downlinks (initial orbital parameters of HEO SRS satellite)

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FIGURE 11-2

Interference (I0/N0 probability curves) from GSO FSS downlinks into NGSO SRS downlinks (current orbital parameters of HEO SRS satellite)

Results of interference analysis from NGSO SRS downlinks into GSO FSS downlinks are provided in the Table 11-7, containing percentages of time, when threshold I0/N0 values are exceeded for different receiving FSS earth stations.

TABLE 11-7

Percentages of time, when threshold I0/N0 value (-12.2 dB) is exceeded for receiving FSS earth stations

NGSO SRS system initial orbit NGSO SRS system current orbit parameters parameters (330 000/600 km, (280 000/57 000 km, inclination 51.4 degrees) inclination 56.8 degrees) Scenario 1 Scenario 2 Scenario 1 Scenario 2

FSS ES1 (0.6 m) 1.75% I0/N0 not exceeded 0.116% I0/N0 not exceeded

FSS ES2 (1.8 m) 1.07% I0/N0 not exceeded 0.0634% I0/N0 not exceeded

FSS ES3 (2.4 m) 1.07% I0/N0 not exceeded 0.0634% I0/N0 not exceeded

11.2.6.3.5 Summary and conclusion Dynamic simulations have been performed to assess the potential for interference between the HEO NGSO SRS systemsand GSO FSS systems in the 14.8-15.35 GHz band in the downlink direction for different set of FSS earth stations and their relative locations with respect to SRS earth station. Different NGSO SRS system orbit parameters were also taken into account.

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Potential for interference into FSS downlinks exists for the worst case interference scenario (same service area of SRS/FSS earth stations). For FSS downlinks I0/N0 may exceed-12.2 dBfor up to 1.75% of time. For the HEO NGSO SRS systems the aggregate interference from FSS downlinks exceeds –6 dB for up to 0.673% of time, which does not meet the protection criterion for SRS systems in Recommendation ITU-R SA.609-2. However, taking into account possible additional operational limitations for NGSO SRS systems (limitation on minimal operational height (up to 40 000 km) of NGSO SRS satellites to protect terrestrial services, operation of NGSO SRS systems in VLBI mode, stipulating operation on maximum distance from the Earth), protection criterion could be met.

11.2.7 FSS (s-E) and AMS and MS The studies as contained in the section concerning the sharing between FSS (space-to-Earth) and MS in the band of 14.5-14.8 GHz are applicable to the 14.8-15.35 GHz band.

11.2.8 FSS (s-E) and FS The studies as contained in the section concerning the sharing between FSS (space-to-Earth) and FS in the band of 14.5-14.8 GHz are applicable to the 14.8-15.35 GHz band.

11.2.8.1 Interference from FS to FSS (s-E) This section contains results of a compatibility study between the fixed service (FS) and GSO fixed-satellite service (GSO FSS) (space-to-Earth) in the common frequency band 14.8-15.35 GHz in Region 1 under scenario 1: receiving FSS earth station (ES) interfered with by emissions of a single transmitting FS terrestrial station (TS). Under scenario 1, allowable interference from a single transmitting FS TS at the input of receiving FSS ES was analyzed as well as the required separation distance between the FS TS and the FSS ES which ensures allowable error performance for the FSS hypothetical reference digital path, specified in the Recommendation ITU-R S.1432. The required separation distances to ensure protection of receiving FSS ES interfered with by transmitting FS TS were calculated in accordance with the methodology of the Recommendation ITU-R P.452-14 under the following conditions: – calculations are performed for frequency 15.0 GHz (λ = 2 cm); – calculations were done for radio-climatic zone А2 (all land areas far from sea); – height of FSS ES antenna centre was 3 m above the smooth-Earth surface; – height FS TS antenna centre was 30 m above the smooth-Earth surface; – calculations were performed for a smooth surface, without taking into consideration interference path profile; – maximum allowable interference from other systems in the fixed and mobile services having co-primary status was used as a criterion (interference/noise ratio, Iag/N = –12.2 dB (6%), taken from the Recommendation ITU-R S.1432). The calculations assumed that the FS TS and FSS ES could be located at any point of Region 1 between 78.3º South and 78.3º North. For a multitude of FS TS located on the Earth surface, azimuth angles of antenna beams are assumed equiprobable within the range of 0º to 360º.

11.2.8.1.1 Technical characteristics of GSO FSS earth stations Typical characteristics of FSS ES are used in the band 10-17 GHz (see § 4 of Annex 5 to Document 4A/125). Considering that in this study FSS operation conditions are analyzed for the new frequency band 14.8-15.35 GHz, in the interference calculation the reference antenna radiation pattern of receive FSS ES (VSAT) is used as shown in recommends 2.1 of the Recommendation Rep. ITU-R S.2365-0 357

ITU-R S.1855 taking into account Note 2 that “… some antennas with D/λ < 46.8 can meet the more stringent radiation pattern envelope in recommends 2.1”. Calculations also consider that all VSAT station antennas with 0.6 to 1.2 m diameter (D/λ = 30-60, f = 15 GHz) have the same radiation pattern for off-axis angles φ ≥ 3 degrees. Additionally, according to the Recommendation ITU-R S.580-6, Gateway earth station antennas with 2.4 to 6.0 m diameter (D/λ = 120–300, f = 15 GHz) also have more stringent reference radiation pattern.

11.2.8.1.2 Calculation of permissible interference level at the input of FSS earth station receiver Maximum interference level at the input of FSS ES receiver from a single FS TS, which provides permissible error performance degradation for the FSS hypothetical reference digital path is defined by the equation:

Pi = Pn  (Ise / N) (11-1) where:

Pi : single interference power spectral density at the input of the FSS ES receiver (dBW/МHz) 6 Pn = kT × (10 ) : noise power spectral density of the FSS ES (dBW/МHz)

Ise/N : permissible interference-to-noise ratio at the input of the FSS ES receiver (dB) Т = 140К : typical equivalent noise temperature of the FSS ES in the 15 GHz band assumed for calculations. Due to high selectivity of both FS terrestrial station and receiving FSS earth station antennas in 15 GHz band, the interference with maximum level could impact the receiving FSS earth station only from different azimuthal directions. The calculation of protective distances on the methodology of the Recommendation ITU-R P.452-14 for the worst-case interference scenario of opposite azimuthal directions of receiving FSS ES antenna and transmitting FS station antenna could be carried out on the basis of protective criterion I/N = –12.2 dB (6%), specified in Recommendation ITU-R S.1432. Then permissible value of single interference power spectral density at the input of the FSS earth station will be Pi = –147.1 –12.2 = –159.3 dBW/МHz. According to the Recommendation ITU-R S.523, interference power spectral density Pi = –159.3 dBW/МHz shall not be exceeded for more than 20% of any month.

11.2.8.1.3 Technical characteristics of FS terrestrial stations Table 11-8 shows FS (point-to-point) system characteristics from the Recommendation ITU-R F.758, necessary to assess interference and calculate frequency sharing with other services in the band 14.4-15.35 GHz.

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TABLE 11-8 General characteristics of P-P FS systems in the band 14.4-15.35 GHz System parameters for FS in the band 14.4-15.35 GHz System 1 System 2 System 3 Reference Recommendation ITU-R F.636 Modulation 128-QAM FSK 4-PSK Channel spacing, МHz 28.0 3.5 10.5 FS TS antenna gain G(max), dBi 31.9 37.0 45.0 (1) Dant/λ (15 GHz) 16.5 30 75 Reference FS TS antenna radiation pattern According to the Rec. ITU-R F.1245 Maximum e.i.r.p., dBW 41.9 … 46.9 31.0 … 37.0 38.0 e.i.r.p. spectral density (max), dBW/1МHz 27.4 … 32.4 25.6 … 31.6 28.0

(1) The relationship between Gmax and Dant/ is given in Recommendation ITU-R F.699.

When calculating the required separation distance between FS TS and FSS ES, maximum e.i.r.p. spectral density is taken from Table 11-8 for System 1 (32.4 dBW/1 MHz). The FS TS antenna radiation pattern is as given in the Recommendation ITU-R F.1245. According to the BR IFIC No. 2737 (Terrestrial services) of 05.02.2013, 13 438 FS terrestrial stations were filed in Region 1 within the band 14.8-15.35 GHz, and information on their antenna elevation angle was submitted to the BR for 13 154 stations. The majority of FS terrestrial stations (10 857 or ≈ 83.3%), filed in the ITU, have antenna elevation angles within 0±0.5 degrees, so when calculating interference from transmitting FS TS we shall assume that the worst interference scenario is the case where antenna beam of transmitting FS TS is directed precisely to receiving FSS ES at the elevation angle 0 degree (ELTS = 0°).

11.2.8.1.4 Calculation of permissible transmission loss and required separation distance between transmitting FS TS and receiving FSS ES in Region 1

Methodology for calculation of permissible transmission loss Lperm (dB) and separation distance S (km) between interferer and interfered-with station from the Recommendation ITU-R P.452-14 can be applied for time percentage from 0.001% to 50% of a year. The required separation distance between FS TS and FSS ES in Region 1 was calculated for two examples of interference path: the first example was for Europe-Asia area and the second example – for Africa area. For the interference path in the Europe-Asia area, the interference statistics for 20% of any month corresponded to 9.84% of a year, and in the Africa area – to 17.5% of a year. Table 11-9 shows the calculation results for a separation distance S (km) according to the worst interference scenario where antenna beam of transmitting FS TS is directed exactly to receiving FSS ES, and antenna beam of FSS ES is directed to FS TS (the case of opposite azimuthal antenna orientation). With that, the angle φ between FSS ES receiving antenna axis and the direction to the source of interference (transmitting FS TS) is equal to the elevation angle (ELES) of FSS ES antenna. Minimum FSS ES antenna elevation angle is assumed to be ELES = 3 degrees according to RR No. 21.14, and separation distance S (km) is also calculated for elevation angles 10 and 20 degrees. Rep. ITU-R S.2365-0 359

TABLE 11-9 Calculation of permissible transmission loss and separation distance between transmitting FS TS and receiving FSS ES in Region 1 (worst case)

FSS ES FSS ES Permissible transmission loss Lperm (dB) and separation distance S (km) elevation gain in in Region 1 between FS TS and FSS ES at various FSS ES , (degree) the antenna elevation angles (degree) direction to Region 1 (Europe, Asia) Region 1 (Africa) FS TS Percentage of year = 9.84% Percentage of year = 17.5% (dBi) Lperm (dB) S (km) Lperm (dB) S (km) 3 17.1 208.0 124.5 208.8 188.4 10 7.0 198.2 77.3 198.2 137.4 20 –0.5 19.2 55 191.2 113.7

It follows from the calculations, that the separation distance between FS TS and FSS ES in Region 1 shall not be less than S1 = 125 to 55 km (in the Europe-Asia area) and S2 = 188 to 114 km (in the Africa area), for the worst case where FSS ES and FS TS have opposite azimuthal antenna orientation and for FSS ES antenna elevation angles ELES = 3° to 20°. It should be noted that the probability of opposite azimuthal FS TS and FSS ES antenna beam orientation will be small due to FSS ES and FS TS narrow antenna beamwidth (BW). Thus, according to the Recommendations ITU-R BO.1213 and ITU-R F.1245, beamwidth of FSS ES antenna is within the range of BW(–1 dB)ES = 0.134° to 1.34°, and for FS TS antenna (System 1, Table 11-8) BW(−1 dB)TS = 2.4°. Using rectangular approximation for FSS ES and FS TS antenna main lobe at –1 dB gain, we shall calculate the probability рworst for the case of opposite azimuthal orientation of FS TS and FSS ES antenna beams. With equiprobable azimuthal angles of multitude of FS TS antenna beams within 0º to 360º, and azimuthal angles of multitude of FSS ES antenna beams within 0º to 180º (in the direction to GSO), and with the specified TS and ES BW, pworst will fall within the range:

pworst = (BWES+ BWTS)/180º х (BWTS)/360º = 0.0094% to 0.014%, i.e. the case of the opposite azimuthal FS TS and FSS ES antenna orientation, which requires maximum separation between these stations, has very low probability.

At the same time the probability рbest of the best azimuthal orientation of the FSS ES and the FS TS antenna beams, when the interference reaches the minimum level (for off-axis angles 48º ≤  ≤ 180º where the FS TS and the FSS ES antenna gains are minimum constant values), can be estimated as:

рbest = (180º – 48º)ES/180º х (180º – 48º)TS/180º = 0.538 (53.8%), i.e. the required separation distance will be minimum for all elevation angles of the FSS ES and the FS TS antenna for more than a half (53.8%) of possible azimuthal orientations of the FS TS and the FSS ES antenna. A more detailed calculation of the separation distance between the FS TS and the FSS ES at all azimuth directions was performed for Region 1 (Europe, Asia), where the operation of the FSS ES is possible at smaller elevation angles. Midpoint coordinates of the calculated interference path are assumed to be 50ºN and 70ºE. Table 11-10 shows calculated separation distances S (km) for antenna azimuth angles of the FSS ES and/or the FS TS in the range of AZ = 0° to 50°, taking into account that reference antenna patterns

360 Rep. ITU-R S.2365-0 of the FSS ES and the FS TS antenna for off-axis angles (48º ≤  ≤ 180º) are constant values and the separation distance will not vary. For mutual off-set of FSS ES and FS TS antenna beams from the opposite direction by AZ ≥ 48 degrees, the required separation distance reduces to the minimum value Smin = 23.7 km. For further reduction of the minimum separation distance, additional measures could be used: channel frequency planning, real site shielding and other natural factors. It should also be noted that in Region 1 (Africa), FSS ES might use higher antenna elevation angle (more than 20°) in comparison with high-latitude (North) areas of Region 1 (Europe, Asia) where ELES = 3° to 10°, that simplifies the compatibility between FSS ES and FS TS in the 15 GHz band.

11.2.8.1.5 Results based on the above assumptions Compatibility between the GSO-FSS (space-to-Earth) and the fixed service in the common frequency band 14.8-15.35 GHz is ensured by limiting the minimum permissible separation distance between transmitting FS TS and receiving FSS ES. Separation distances for all possible azimuthal directions of FSS ES and FS TS antenna (from 0 to 180 degrees) were calculated for the interference path in Region 1 (Europe, Asia) under clear sky condition and for 9.84% of the year, according to Recommendation ITU-R P.452-14. In the interference calculation the reference antenna radiation pattern of receive FSS ES is used as shown in recommends 2.1 of Recommendation ITU-R S.1855 taking into account Note 2 that “… some antennas with D/λ < 46.8 can meet the more stringent radiation pattern envelope in recommends 2.1”. Required protection for all types of receiving FSS ES (see Table 4-1) from transmitting FS TS when sharing the frequency band 14.8-15.35 GHz can be provided at separation distances from 125-188 km to 23.7 km depending on the mutual orientation of the FS TS and the FSS ES antenna axes. Probability of the worst case of opposite azimuth orientation of FS TS and FSS ES antenna with the elevation angle of 3 degrees which leads to maximum separation distance between stations (135 to 205 km), is extremely low (0.0094% to 0.014%). The required separation distance for FSS ES with higher elevation angles of 10 to 20 degrees and for opposite azimuth orientation of the antennas is reduced to 60-150 km. For 53.8% of possible cases of mutual azimuth orientation of FS TS and FSS ES antenna, the required separation distance will be minimum Smin = 23.7 km for any elevation angle of the FSS ES and the FS TS antenna. These results were obtained with maximum level of e.i.r.p. interference spectral density from FS TS (32.4 dBW/1 MHz, System 1, Table 11-8) to receiving FSS ES. Protection of receiving FSS ES from other types of FS TS (Systems 2 and 3, Table 11-8) is provided with smaller separation distances due to the interference level reduced by 0.8 to 4.4 dB. The study results for the frequency band 14.8-15.35 GHz could be also applied for the frequency band 14.5-14.8 GHz, taking into account that transmitting FS station characteristics required to assess interference and perform studies on compatibility with other services are specified in the Recommendation ITU-R F.758 for the frequency band 14.4-15.35 GHz.

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TABLE 11-10 Calculation of permissible transmission loss and separation distance between transmitting FS TS and receiving FSS ES in Region 1 Required percentage of a year = 9.84% (corresponds to 20% of the worst month). Region 1 (Europe, Asia), latitude/longitude of the interference path midpoint = 50/70 deg.

EL of AZ of Gain of Permissible transmission loss Lperm (dB) and the separation distance S (km) between a single transmitting FS TS and a receiving FSS ES with azimuthal FSS FSS FSS ES off-set between the FSS ES and the FS TS antenna by AZ (deg.) from the precise opposite direction ES ES in the (deg.) (deg.) direction AZ = 0 AZ = 10 AZ = 20 AZ = 30 AZ = 40 AZ ≥ 50 to FS TS (dBi) Lperm (dB) S (km) Lperm (dB) S (km) Lperm (dB) S (km) Lperm (dB) S (km) Lperm (dB) S (km) Lperm (dB) S (km) 0 17.1 208.88 124.5 190.0 53.9 182.5 47.8 178.1 44.8 175.0 42.6 173.0 41.4 10 6.5 203.4 81.4 179.4 45.7 171.9 40.6 167.5 38.0 164.4 35.9 162.4 34.9

20 –0.6 196.3 59.6 172.3 40.9 164.8 36.2 160.4 33.7 157.3 30.0 155.3 29.2

= 3 =

30 –5.0 191.9 55.4 167.9 38.1 160.4 33.7 156.0 29.5 152.9 28.0 150.9 26.8

EL 40 –8.0 188.9 52.9 164.9 36.2 157.4 30.1 153.0 28.1 149.9 26.2 147.9 25.0 ≥ 50 –10.0 186.9 51.4 162.9 35.2 155.4 29.3 151.0 26.9 174.9 25.0 145.9 23.7 0 7.0 198.2 77.3 179.9 46.1 172.4 40.9 168.0 38.1 164.9 36.2 162.9 35.2 10 3.3 200.2 70.0 176.2 43.4 168.7 38.6 164.3 35.9 161.2 34.0 159.2 31.2

0 20 –1.7 195.2 58.5 171.2 40.3 163.7 35.8 159.3 31.3 156.2 29.5 154.2 28.7

= 1 = 30 –5.4 191.5 55.0 167.5 38.0 160.0 31.6 155.6 29.4 152.5 27.8 150.5 26.6

EL 40 –8.3 188.6 52.7 164.6 36.0 157.1 29.9 152.7 27.9 149.6 26.0 147.6 24.8 ≥ 50 –10.0 186.9 51.4 162.9 35.2 155.4 29.3 151.0 26.9 147.9 25.0 145.9 23.7 0 –0.5 191.2 55.0 172.4 40.9 164.9 36.2 160.5 33.7 157.4 30.1 155.4 29.3 10 –1.7 195.2 58.5 171.2 40.3 163.7 35.8 159.3 31.3 156.2 29.5 154.2 28.7

20 –4.2 192.7 56.2 168.7 38.6 161.2 34.0 156.8 29.8 153.7 28.4 151.7 27.3

= 20 = 30 –6.8 190.1 54.0 166.1 37.0 158.6 30.8 154.2 28.7 151.1 26.9 149.1 25.7

EL 40 –9.0 187.9 52.1 163.9 35.8 156.4 29.6 152.0 27.5 148.9 25.6 146.9 24.4 ≥ 50 –10.0 186.9 51.4 162.9 35.2 155.4 29.3 151.0 26.9 147.9 25.0 145.9 23.7

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11.2.8.2 Interference from FSS (s-E) to FS This section contains results of compatibility study between the fixed service (FS) and GSO fixed-satellite service (GSO FSS) (space-to-Earth) in the common frequency band 14.8-15.35 GHz under scenario 2: receiving FS terrestrial station (TS) interfered with by aggregate interference from GSO FSS satellites (space-to-Earth). Under scenario 2, analysis assessed average probability of interference level exceeding permissible criterion, from GSO FSS satellites to receiving FS terrestrial station located at any point of the Earth’s surface visible from GSO. This analysis should be taken into account during determination of the power flux-density limits at the Earth’s surface produced by GSO FSS satellites in the band 14.8-15.35 GHz being studied for additional primary allocation to GSO FSS (space-to-Earth) in Region 1.

Average probability Р(φ, e0, α) of interference to FS receiving stations was calculated entirely based on the methodology of Document 4А/317 containing assessment of the probability of harmful interference from GSO BSS satellites in the band 21.4-22.0 GHz to FS terrestrial stations. That document was approved by WP 4A meeting in March, 2010 within the studies on WRC-12 agenda item 1.13. The following initial data were used for all calculations: 1) Frequency f = 15.0 GHz, wavelength λ = 2 cm. 2) Power flux density D = –124 dBW/m2/1 MHz of hypothetic FSS satellite (space-to-Earth) for arrival angles from 0º to 5º above the horizon. 3) Spectral noise-power density of receiving FS TS is assumed to be N = –139.8 dBW/MHz and –136.0 dBW/MHz. 4) Maximum FS TS antenna gain (Systems 1, 2 and 3) Gmax = 45.0; 37.0; 31.9 dBi. 5) It is assumed that FS TS could have any location point on the Earth’s surface between ≈74º south and 74º north latitude. 6) Hypothetic FSS satellites are uniformly positioned on the GSO with the angular separation between satellites γ = 3º or 10º. All satellite positions are assumed to be equiprobable. Interference from 4 nearest satellites was taken into account. Interference from more distant satellites was not taken into consideration because calculation showed it very small. Proposed power flux density limits −124 to –114 dBW/m2/MHz are the same as established by the Radio Regulations for the frequency band 12.5–12.75 GHz (space-to-Earth) allocated to GSO FSS in Region 1 for countries listed in RR Nos. 5.494 and 5.496 (see Table 21-4 of RR Article 21). Moreover, power flux density −124 dBW/m2/МHz corresponds to e.i.r.p. spectral density –20 dBW/Hz for hypothetical FSS satellite (space-to-Earth), specified in section 4 – General FSS characteristics;

– Permissible level of long-term aggregate interference (Iag) from GSO FSS satellites to the receiving FS TS according to Recommendation ITU-R F.758 is defined by the criterion Iag/N = −10 dB, where N – noise level of receiving FS station.

11.2.8.2.1 Technical characteristics of FS terrestrial stations Table 11-11 shows FS (point-to-point) system characteristics taken from the Recommendation ITU-R F.758, necessary to assess interference and calculate frequency sharing with other services in the band 14.4-15.35 GHz.

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TABLE 11-11 Examples of characteristics of Р-Р FS systems in the band 14.4-15.35 GHz System parameters for FS in the band 14.4-15.35 GHz System 1 System 2 System 3 Reference ITU-R Recommendation F.636 Modulation 128-QAM FSK 4-PSK Antenna gain G(max), dBi 31.9 37.0 45.0 (1) Dant/λ (15 GHz) 16.5 30 75 Channel spacing and receiver noise bandwidth, MHz 28 3.5 10.5 Receiver noise figure, dB 8 5 4 Feeder/multiplexer loss (minimum), dB 0 0 0 Reference radiation pattern of FS TS antenna According to the Recommendation ITU-R F.1245 Noise power density (dB(W/MHz)) –136.0 –139.0 –139.8 Interference power density, dBW/MHz –146.0 –149.0 –149.8

(Iag/N = −10 dB)

(1) The relationship between Gmax and Dant/ is given in Recommendation ITU-R F.699.

The FS TS antenna radiation patterns for System 1, 2 and 3 are taken from Recommendation ITU-R F.1245. According to the BR IFIC No. 2737 (Terrestrial services) of 05.02.2013, 13 438 FS terrestrial stations were filed in Region 1 within the band 14.8-15.35 GHz, and information on their antenna elevation angle was submitted to the BR for 13 154 stations. Most of these stations have elevation angle 0 degrees, but some FS stations have higher elevation angles, up to +33 degrees. According to the BR IFIC No. 2737, interference calculations assumed that FS TS antenna elevation angles are: e = 0º (with weighting factor 94% for elevation angles from –1° to +1°), e = 2º (with weighting factor 1.33%), e = 3º (with weighting factor 0.56%), e = 5° (for elevation angles from 4° to 33°, with weighting factor 1.43%), e = 2º (for elevation angles less than or equal to 2º with weighting factor 2.68%), see Table 11-12.

TABLE 11-12 Distribution of antenna elevation angles for FS stations in the band 14.8-15.35 GHz for Region 1

Elevation angle of FS TS Number of FS terrestrial Weight antenna stations filed in Region 1 W  (degrees) e0 4 … 33 188 0.01429 3 73 0.00555 2 175 0.01330 –1 … +1 12 365 0.94002 –33 … –2 353 0.02684

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Interferences from satellites visible at FS TS antenna elevation angle below minus 1 degree were not taken into account. Minimum attenuation of interfering signal from GSO FSS satellite in atmospheric gases was calculated using atmospheric parameters specified in the Recommendation ITU-R SF.1395. Impact of interference signal refraction in the atmosphere was not taken into account. Also calculations assumed that FS TS antenna beams could be deflected from their precise direction to the GSO by angle not less than 1.5°, because such a deflection is provided for by the Radio Regulations (see Table 21-1 of RR Article 21) for the band 10-15 GHz which is partially overlapped with the studied band 14.8-15.35 GHz.

11.2.8.2.2 Calculation of probability for exceeding the permissible interference criterion at the input of receiving FS TS Probability of exceeding the permitted interference criterion was calculated for two cases: – Case 1 – FS TS antenna beams are not assumed to be deflected from exact pointing to GSO; – Case 2 – FS TS antenna beams are assumed to be deflected from exact GSO direction by the angle ε ≥ 1.5º (similarly to Table 21-1 of RR Article 21). All other azimuth angles А are equiprobable except for two prohibited angle ranges χ(ε, φ), where ε = ±1.5º. Calculation results for average probability Р of interference to receiving FS stations in the 15 GHz band are shown in Tables 11-13 and 11-14.

TABLE 11-13 Probability of exceeding the permissible interference criterion, % (N = 139.8 dBW/MHz)

Separation of GSO FS TS antenna gain 31.9 37 45 FSS satellites Beam direction (dBi) (degree) (dBi) (dBi) 3 Without initial avoidance 3.92% 3.47% 2.82% 3 With avoidance 1.5° 1.40% 1.01% 0.49% 10 Without initial avoidance 1.40% 1.13% 0.82% 10 With avoidance 1.5° 0.38% 0.23% 0.076%

TABLE 11-14 Probability of exceeding the permissible interference criterion, % (N = 136 dBW/MHz)

Separation of GSO FS TS antenna gain 31.9 37 45 FSS satellites (dBi) (degree) Beam direction (dBi) (dBi) 3 Without initial avoidance 2.65% 2.28% 1.76% 3 With avoidance 1.5° 0.37% 0.15% 0.018% 10 Without initial avoidance 0.75% 0.62% 0.45% 10 With avoidance 1.5° 0.05% 0.015% 0.0014%

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11.2.8.2.3 Results based on above assumptions

The probability of exceeding the long-term interference criterion Iag/N = −10 dB, without mandatory FS TS antenna beam deflection from exact GSO direction, varies from 3.92% to 0.45%. Under the assumption of FS TS antenna beam deflection from exact GSO direction by not less than 1.5 degree, the probability of exceeding the long-term interference criterion, i.e. a percentage of receiving FS stations interfered with varies from 1.4% to 0.0014%. It should be taken into consideration that the above estimate is overestimated, as the majority of FS stations operate with SNR margin, and also because the calculation didn’t consider rain attenuation of interfering signal and its correlation with attenuation of wanted signal over FS path. However it should be taken into account that fixed stations possible additional SNR margin cannot be assured and in particular the fade margin of fixed station link is assigned for particular performance requirements and is not designed for interference mitigation. The study results for the frequency band 14.8-15.35 GHz could be also applied for the frequency band 14.5-14.8 GHz, taking into account elevation angle statistics for the receiving FS station antenna and the fact that receiving FS station characteristics required to assess interference and perform studies on compatibility with other services are specified in the Recommendation ITU-R F.758 for the frequency band 14.4-15.35 GHz.

11.2.9 FSS (s-E) and radio astronomy Satellite transmissions have the potential to cause serious interference to the RAS since such interference is likely to be received via the main beam and inner side lobes, with significant gain level. In accordance with Table 1 Annex 1 to Recommendation ITU-R RA.769 the protection criteria for radio astronomy continuum observations in the frequency band 15.35-15.4 GHz is pfd level of −156 dBW/ m2 in 50 MHz which corresponds to pfd level of –173 dBW/ m2 in 1 MHz. However, in accordance with Recommendation ITU-R RA.769, this level, given in Table 1 of Annex 1 to Recommendation ITU-R RA.769, is applicable to terrestrial sources of interfering signals and assumes that interference is received through a 0 dBi side lobe. Interference from GSO satellites is a case of particular importance because may be created through the side lobes of radiotelescope antenna with higher gain. In accordance with Recommendation ITU-R RA.769 a value of 5° should therefore be regarded as the requirement for minimum angular spacing between the main beam of a radio astronomy antenna and the GSO. In the model antenna response of Recommendation ITU-R SA.509, the side-lobe level at an angle of 5° from the main beam is 15 dBi. Thus, to avoid interference detrimental to a radio telescope meeting the antenna side-lobe performance of Recommendation ITU-R SA.509, pointed to within 5° of the transmitter, it is desirable that the satellite emissions be reduced 15 dB below the pfd given in Table 1 of Recommendation ITU-R RA.769. VLBI observations, where signals from widely separated antennas are recorded and correlated after the observations, are much less susceptible to interference. This is reflected in the threshold pfd level for VLBI observations in this band. The threshold pfd level for protection of the radio astronomy stations using for VLBI is presented in Table 3 of Annex 1 to Recommendation ITU-R RA.769 and equal to –189 dBW/ m2 Hz, corresponds to –129 dBW/ m2 in 1 MHz. In accordance with Radio Regulations the boundary between the out-of-band and spurious domains occurs at frequencies that are separated from the centre frequency of the emission by the values shown in Table 1 of Annex 1 to RR Appendix 3. In general, the boundary, on either side of the centre frequency, occurs at a separation of 250% of the necessary bandwidth, or at 2.5 BN.

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The frequency band allocated to the RAS will be in the FSS transmitter spurious domain, as it is defined in Radio Regulations. In this respect the attenuation values used in the calculations of the maximum emission power levels in the spurious domain will be defined by the values specified in Table 1 of RR Appendix 3. Calculation results of unwanted emission caused by FSS satellite operating in the frequency band 14.85-15.1 GHz to the radio astronomy service (Continuum and VLBI) in the spurious domain in the frequency band 15.35-15.4 GHz are given in Table 11-15.

TABLE 11-15 FSS e.i.r.p. (dB(W/4kHz)) 16 Attenuation (dB) below the power supplied to the antenna transmission line 60 RF filter rejection (dB) 20 Minimum spreading factor (dB) 162.1 Maximum spectral pfd (dB(W/m2·4kHz)) –226.1 Continuum Assumed bandwidth (MHz) 50 Threshold pfd in assumed bandwidth for 0 dBi side-lobe level (dB(W/ m2·50MHz)) –156 Threshold pfd for 0 dBi side-lobe level in 4 kHz (dB(W/m2·4kHz)) –197 Threshold pfd for 15 dBi side-lobe level in 4 kHz (dB(W/m2·4kHz)) –212 Threshold margin (dB) 14.1 VLBI Reference bandwidth (Hz) 1 Threshold pfd level in reference bandwidth (dB(W/m2·Hz)) –189 Threshold pfd level in 4 kHz (dB(W/m2·4kHz)) –153 Threshold margin (dB) 73.1

The estimation results show that the FSS unwanted emissions (s-E) do not exceed the threshold levels for protection of radio astronomy stations (Continuum, VLBI) in the frequency band 15.35-15.4 GHz. For RAS continuum observations the margin is 14 dB, for VLBI observations the margin is 73 dB.

11.3 Summary of studies for the band 14.8-15.35 GHz Compatibility between FSS (Earth-to-space and space-to-Earth) links and SRS DRS systems (except return inter-orbit links) in the band 14.8-15.35 GHz is achievable with coordination measures, considering the same status for SRS and FSS. Compatibility of the FSS uplinks with respect to the SRS DRS return inter-orbit links in the band 14.8-15.35 GHz will not be met without adequate mitigation techniques which have not been defined. Compatibility of the GSO FSS systemswith HEO NGSO SRS systems in the 14.8-15.35 GHz band (space-to-Earth) could be feasible, assuming the same regulatory status for existing SRS applications and FSS. Taking into account that there is a potential of interference into FSS downlinks from NGSO SRS downlinks (I0/N0 may exceed –12.2 dB for up to 1.75% of time for the same service area case), new FSS allocation in the 14.8-15.35 GHz (space-to-Earth) could be implemented on a condition that GSO FSS systems shall not claim protection from existing SRS applications (HEO NGSO SRS downlinks). Rep. ITU-R S.2365-0 367

Regarding compatibility between FSS (Earth-to-space) and the mobile service, the same conclusions drawn for the band 14.5 – 14.8 GHz apply to the band 14.8-15.35 GHz. The calculation results of unwanted emissions in the spurious domain in the RAS frequency band 15.35-15.4 GHz from FSS (space-to-Earth) satellite operating in the frequency band 14.85-15.1 GHz showed that compatibility is feasible.

12 Frequency band 15.35-15.4 GHz No sharing studies were submitted to the ITU-R for FSS (E-s) satellite systems and any service in the band 15.35-15.4 GHz.

13 Frequency bands 15.4-15.43 GHz, 15.43-15.63 GHz and 15.63-15.7 GHz The allocations of these bands in RR Article 5 are shown below.

TABLE 13-1 Excerpts from Article 5 of the Radio Regulations on allocation to services in 15.4-15.7 GHz (including WRC-12 amendments)

Allocation to services Region 1 Region 2 Region 3 15.4-15.43 RADIOLOCATION ADD 5.A121 ADD 5.B121 AERONAUTICAL RADIONAVIGATION 5.511D 15.43-15.63 FIXED-SATELLITE (Earth-to-space) 5.511A RADIOLOCATION ADD 5.A121 ADD 5.B121 AERONAUTICAL RADIONAVIGATION 5.511C 15.63-15.7 RADIOLOCATION ADD 5.A121 ADD 5.B121 AERONAUTICAL RADIONAVIGATION 5.511D 5.A121 In the frequency band 15.4-15.7 GHz, stations operating in the radiolocation service shall not cause harmful interference to, or claim protection from, stations operating in the aeronautical radionavigation service. (WRC-12) 5.B121 In order to protect the radio astronomy service in the frequency band 15.35-15.4 GHz, radiolocation stations operating in the frequency band 15.4-15.7 GHz shall not exceed the power flux-density level of −156 dB(W/m2) in a 50 MHz bandwidth in the frequency band 15.35-15.4 GHz, at any radio astronomy observatory site for more than 2 per cent of the time. (WRC-12) 5.511D Fixed-satellite service systems for which complete information for advance publication has been received by the Bureau by 21 November 1997 may operate in the bands 15.4-15.43 GHz and 15.63-15.7 GHz in the space-to-Earth direction and 15.63-15.65 GHz in the Earth-to-space direction. In the bands 15.4-15.43 GHz and 15.65-15.7 GHz, emissions from a non-geostationary space station shall not exceed the power flux-density limits at the Earth’s surface of –146 dB(W/(m2.MHz)) for any angle of arrival. In the band 15.63-15.65 GHz, where an administration plans emissions from a non-geostationary space station that exceed –146 dB(W/(m2.MHz)) for any angle of arrival, it shall coordinate under No. 9.11A with the affected administrations. Stations in the fixed-satellite service operating in the band 15.63-15.65 GHz in the Earth-to-space direction shall not cause harmful interference to stations in the aeronautical radionavigation service (No. 4.10 applies). (WRC-97)

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5.511A The band 15.43-15.63 GHz is also allocated to the fixed-satellite service (space-to-Earth) on a primary basis. Use of the band 15.43-15.63 GHz by the fixed-satellite service (space-to-Earth and Earth-to- space) is limited to feeder links of non-geostationary systems in the mobile-satellite service, subject to coordination under No. 9.11A. The use of the frequency band 15.43-15.63 GHz by the fixed-satellite service (space-to-Earth) is limited to feeder links of non-geostationary systems in the mobile-satellite service for which advance publication information has been received by the Bureau prior to 2 June 2000. In the space-to-Earth direction, the minimum earth station elevation angle above and gain towards the local horizontal plane and the minimum coordination distances to protect an earth station from harmful interference shall be in accordance with Recommendation ITU-R S.1341. In order to protect the radio astronomy service in the band 15.35-15.4 GHz, the aggregate power flux-density radiated in the 15.35-15.4 GHz band by all the space stations within any feeder-link of a non-geostationary system in the mobile-satellite service (space-to-Earth) operating in the 15.43-15.63 GHz band shall not exceed the level of 156 dB(W/m2) in a 50 MHz bandwidth, into any radio astronomy observatory site for more than 2% of the time. (WRC-2000) 5.511C Stations operating in the aeronautical radionavigation service shall limit the effective e.i.r.p. in accordance with Recommendation ITU-R S.1340. The minimum coordination distance required to protect the aeronautical radionavigation stations (No. 4.10 applies) from harmful interference from feeder-link earth stations and the maximum e.i.r.p. transmitted towards the local horizontal plane by a feeder-link earth station shall be in accordance with Recommendation ITU-R S.1340. (WRC-97)

13.1 Review of Recommendations and Reports A list of relevant Recommendations and Reports that may be useful for sharing studies is in Table 13-2.

TABLE 13-2 Summary of relevant Recommendations/Reports that may be useful for sharing studies in the band 15.4-15.7 GHz

Service Relevant Recommendations Relevant Reports Radiolocation Recommendation ITU-R M.1730 Report ITU-R М.2221 Recommendation ITU-R M.1461 Report ITU-R М.2170 Recommendation ITU-R M.1851 Aeronautical Recommendation ITU-R S.1340 Report ITU-R М.2221 Radionavigation Report ITU-R M.2230 Radioastronomy Recommendation ITU-R RA.769 (adjacent band) Report ITU-R М.2170 Recommendation ITU-R RA.1031-2 Report ITU-R М.2221 Recommendation ITU-R RA.1513-1 Fixed-satellite [Within WP 4A] Recommendation ITU-R S.1340

13.2 Sharing studies for the band 15.4-15.7 GHz 13.2.1 FSS (E-s) and radiolocation WRC-12 agreed on a primary allocation in the 15.4-15.7 GHz band for the radiolocation service. The studies in the ITU-R that led up to this decision focus synthetic aperture radar (SAR) on an aircraft. The band 15.4-17.3 GHz is used by many different types of radars including land-based, transportable, shipboard and airborne platforms. Radiolocation functions performed in the band include airborne and surface search, surface surveillance, ground-mapping, terrain-following, maritime and target-identification. Radar operating frequencies can be assumed to be uniformly Rep. ITU-R S.2365-0 369 spread throughout each radar’s tuning range. The major radiolocation radars operating or planned to operate in the band 15.4-17.3 GHz are primarily for detection of airborne objects and some are used for ground mapping. They are required to measure target altitude, range, bearing, and form terrain maps. Some of the airborne and ground targets are small and some are at ranges as great as 300 nautical miles (556 km), so these radiolocation radars must have great sensitivity and must provide a high degree of suppression to all forms of clutter return, including that from sea, land and precipitation. Some of the radars are used as the airport surveillance detection equipment (ASDE-3) to provide a tool to enhance the situational awareness of air traffic controllers in an effort to reduce runway incursions and aircraft collisions. These radars provide non-cooperative aeronautical surveillance including detection and position information for all aircraft and vehicles on the airport movement area.

13.2.1.1 Radiolocation characteristics Recommendation ITU-R M.1730 recommends: – that the technical and operational characteristics of the radiolocation radars described in Annex 1 should be considered as representative of those operating or planned to operate in the band 15.4-17.3 GHz; – that an I/N ratio of –6 dB, should be used as the required protection level for the portions of the 15.4-17.3 GHz band where there is a radiolocation allocation and that this represents the net protection level if multiple interferers are present; – that in the case of pulsed interference, the criteria should be based on a case-by-case analysis taking into account the undesired pulse train characteristics and, to the extent possible, the signal processing in the radar receiver. Recommendation ITU-R M.1461 should be used in analyzing compatibility between radars operating in the frequency band 15.4-17.3 GHz with systems in other services in this frequency band.

13.2.1.2 Study #1 This section contains a sharing study between fixed-satellite service FSS (Earth-to-space) and ground-based and shipboard stations in the radiolocation service (RLS) operating in 15.4-17.3 GHz. This analysis is a statistical study based on 36 different cases, in which the impact from typical Ku band FSS Earth-to-space operations into 3 representable ground-based and shipboard stations in RLS operating in 15.4-17.3 GHz is studied. The I/N and approximate maximum separation distance are studied, based on a variety of FSS earth station antenna elevation angles, antenna sizes, typical bandwidths and power densities. Natural effects such as terrain (a constant horizon elevation angle of 3° at 500 m is assumed) and propagation effects are considered in the studies, based on Annex 1 of Appendix 7.

13.2.1.2.1 Assumed radiolocation characteristics The studies are based on the following characteristics for RLS, originating from Recommendation ITU-R M.1730-1:

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TABLE 13-3 Radiolocation service characteristics in Study #1

Characteristics System 3 System 4 System 5 Air surveillance, Ground surveillance and Function landing aid, track Surveillance track while scan Shipboard, high Ground-based, low Ground-based, high Platform type power power power Tuning range (GHz) 15.7-17.3 16.21-16.5 15.7-16.2 Antenna gain (dBi) 43 37 43 Mast/deck mount Ground level Antenna height (10 m assumed in this (10 m assumed in this 100 m study) study) Not specified Receiver noise figure (4 dB assumed in this 4 3.97 (dB) study) Transmitter RF emission bandwidth (MHz) at –3 6.8 0.608 540 dB 1st/2nd receiver IF –3 70/40 500/0.750 50 dB bandwidths (MHz) I/N protection criteria –6 –6 –6 (dB)

13.2.1.2.2 Assumed FSS characteristics The FSS emission characteristics are based on Tables 4-1 and 4-2. Antenna sizes studied are 1.2 m, 2.4 m and 6 m. Other FSS characteristics used in this study are shown in Tables 13-4 and 13-5.

TABLE 13-4 Fixed FSS earth station characteristics

Parameter Unit Value Frequency MHz 15400.00 Satellite position degree 5.00 Satellite inclination degree 0.00 Antenna efficiency % 65.00 Antenna pattern Rec. ITU-R S.580 Altitude m 10.00

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TABLE 13-5 FSS earth station pointing characteristics

Elevation angle Azimuth angle Geographical to satellite to satellite coordinates (degree) (degree) 71° N, 15° E 10.14 190.56 61° N, 15° E 20.37 191.40 47° N, 15° E 35.08 193.56 14° S, 15° E 69.87 143.91

13.2.1.2.3 Studied cases A summary of the studied cases are shown in Table 13-6:

TABLE 13-6 Summary of studied cases

Case E/S antenna size Considered radiolocation system 1.20 System 3, 4 and 5 10 deg elevation, 2.40 System 3, 4 and 5 71° N, 15° E 6.00 System 3, 4 and 5 1.20 System 3, 4 and 5 20 deg elevation, 2.40 System 3, 4 and 5 61° N, 15° E 6.00 System 3, 4 and 5 1.20 System 3, 4 and 5 35 deg elevation, 2.40 System 3, 4 and 5 47° N, 15° E 6.00 System 3, 4 and 5 1.20 System 3, 4 and 5 70 deg elevation, 2.40 System 3, 4 and 5 14° S, 15° E 6.00 System 3, 4 and 5

13.2.1.2.4 Results based on the above assumptions The simulation results for the approximate maximum separation distance are summarized in the Figures below:

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FIGURE 13-1 Simulation results showing the approximate max distance to achieve a I/N of –6 dB at 10 and 20 degree elevation angles

Approximate max separation distance at 10 and 20 elevation angles 60.00

50.00

40.00

30.00 km

20.00

10.00

0.00 1.2 1.2 1.2 2.4 2.4 2.4 6 6 6 1.2 1.2 1.2 2.4 2.4 2.4 6 6 6 System 3 System 4 System 5 System 3 System 4 System 5 System 3 System 4 System 5 System 3 System 4 System 5 System 3 System 4 System 5 System 3 System 4 System 5 10 deg 10 deg 10 deg 10 deg 10 deg 10 deg 10 deg 10 deg 10 deg 20 deg 20 deg 20 deg 20 deg 20 deg 20 deg 20 deg 20 deg 20 deg Antenna size, RL system, FSS earth station elevation angle

FIGURE 13-2 Simulation results showing the approximate max distance to achieve a I/N of –6 dB at 35 and 70 degree elevation angles

Approximate max separation distance at 35 and 70 elevation angles 30.00

25.00

20.00

15.00 km

10.00

5.00

0.00 1.2 1.2 1.2 2.4 2.4 2.4 6 6 6 1.2 1.2 1.2 2.4 2.4 2.4 6 6 6 System 3 System 4 System 5 System 3 System 4 System 5 System 3 System 4 System 5 System 3 System 4 System 5 System 3 System 4 System 5 System 3 System 4 System 5 35 deg 35 deg 35 deg 35 deg 35 deg 35 deg 35 deg 35 deg 35 deg 70 deg 70 deg 70 deg 70 deg 70 deg 70 deg 70 deg 70 deg 70 deg Antenna size, RL system, FSS earth station elevation angle

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The results in Figs 13-1 and 13-2 show, for System 3, that the approximate max distance to reach an I/N close to –6 dB, ranges from about 5 to 53 km depending on the elevation angle and the emission characteristics of the earth station. Similarly, for System 4, the distance ranges from 11 to 53 km. For System 5, the distance ranges from about 5 km to 50 km.

13.2.1.3 Study #2 Recommendation ITU-R M.1730-1 lists the parameters of 6 radiolocation systems in the 15.4-17.3 GHz band to be used for assessing the feasibility of sharing in this band. A minimum aggregate I/N ratio of –6 dB for signals from other services with high-duty cycle (e.g. continuous wave, binary phase shift keying, quaternary phase shift keying, noise-like, etc.), which includes the FSS, is required to protect the operations of these systems. Detailed analyses are presented for the airborne radar system listed as System 6 in that recommendation. Table 13-7 lists the relevant parameters of this system. Summary results of performing the same analyses for Systems 1 through 5 listed in Recommendation ITU-R M.1730-1 are also presented in Table 13-10.

TABLE 13-7 Airborne Radiolocation System 6 Technical Characteristics

Characteristic System 6 Characteristic System 6 Typical operational Antenna azimuthal 8 500 3.2 height (m) beamwidth (degrees) Antenna horizontal scan Tuning range (GHz) 15.4-17.3 1-30 rate (degrees/s) Antenna horizontal scan ±45º Modulation Linear FM chirp type (continuous, (electronic) random, sector, etc.) Transmit peak power Antenna vertical scan 500 1, 5 (W) rate (degrees/s) Antenna vertical scan +5° to –45° Pulsewidth (s) 0.05-50 type (electronic) Antenna 1st side-lobe Pulse rise/fall time (ns) 5-100 3.5 dB at 5.2º level Pulse repetition rate 200-20 000 Antenna height Aircraft altitude (pps) 1st/2nd receiver IF –3 dB Maximum duty cycle Up to 0.2 25 bandwidths (MHz) Receiver noise figure Antenna pattern type Pencil 5 (dB) Minimum discernible Antenna type Phased array –100 signal (dBm) Antenna polarization Linear Chirp bandwidth (MHz) < 1 900 Antenna gain (dBi) 35 Transmitter RF emission bandwidth (MHz): 1 850 Antenna elevation –3 dB 3.2 1 854 beamwidth (degrees) –20 dB

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The cosine-squared reference antenna radiation pattern specified in Recommendation ITU-R M.1851, with sidelobe mask and –60 dB gain floor, is assumed to apply to the System 6 antenna, and is illustrated in Fig. 13-3.

FIGURE 13-3 Airborne Radiolocation System 6 Antenna Pattern

-10

Cosine-Squared Sidelobe Pattern -20 M.1851 Peak Pattern With Sidelobe -30 Mask and Gain Floor

-40

Relative Gain (dB)Gain Relative -50

-60

-70 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Off-Axis Angle (degrees)

13.2.1.3.1 FSS characteristics Table 13-8, taken from Annex 7 of the WP 4A Chairman’s Report, Document 4A/242, presents the characteristics of the FSS used in this analysis.

TABLE 13-8 FSS system technical characteristics

Satellite Downlink e.i.r.p. spectral density (dBW/Hz) –20 Satellite G/T See § 13.2.1.3.3, Table 13-11 Earth Station Transmission type (m) VSAT Wideband Point-to- Point Antenna gain (dBi) 43.5 52 53.5 Antenna diameter (m) 1.2 3.3 3.9 PSD at antenna port (dBW/Hz) –42 –49 –50 Average Bandwidth (MHz) 0.58 30.84 2.94 Off-axis radiation pattern BO.1213 BO.1213 BO.1213 S.1855 S.1855 S.1855 Minimum earth station antenna elevation (°) 10 10 10 Antenna feedpoint height above ground level (m) 10 10 10

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13.2.1.3.2 FSS Earth Station Interference into Airborne Radar Receiver Since directive beams are employed by both the FSS earth station and the airborne radar, the worst case situation occurs when there is a main beam antenna coupling between the two stations. For an aircraft at an altitude of 8,500 meters above sea level with a –45° limit on the airborne antenna elevation angle, and a minimum earth station elevation angle of 10°, mainbeam coupling can occur only when the aircraft and earth station are between 12 and 45 km apart and their antenna beams are aligned in azimuth and elevation. Figure 13-4 displays the resulting worst case (mainbeam coupled) I/N from each of the three types of FSS earth station transmissions listed in Table 13-8 into System 6 as a function of the airborne antenna elevation angle assuming the same radar and earth station bandwidths and free space propagation.

FIGURE 13-4 Worst Case (Mainbeam Coupling) I/N into Airborne Radar Receiver

Such main beam couplings would be rare and last for short periods of time. An analysis was performed to provide a more general assessment of potential interference from an earth station into an airborne radar over a wider range of earth station – airborne radar geometries. Figure 13-5 displays I/N contours produced by each of the three types of FSS earth station transmission into the System 6 airborne radar for the different levels of power spectral density (PSD) applied to the earth station antenna indicated in Table 13-8. These contours are based on the following assumptions: – the earth station signal bandwidth is the same as the radar –3 dB IF bandwidth; – the earth station gain towards the aircraft is the gain at the minimum off-axis angle between the geostationary satellite orbit and the aircraft, which is typically in the antenna sidelobes and significantly less than the main beam gain; – the radar antenna is pointing directly at the earth station; and – the Recommendation ITU-R P.528-3 propagation model is used to calculate the 1% probability path loss without taking terrain into account.

376 Rep. ITU-R S.2365-0

FIGURE 13-5 I/N Plot of FSS Interference into an Airborne Radar Receiver

VSAT TRANSMISSION WIDEBAND TRANSMISSION POINT-TO-POINT TRANSMISSION REQUIRED SEPARATION DISTANCE REQUIRED SEPARATION DISTANCE REQUIRED SEPARATION DISTANCE = 423 TO 441 KM = 419 TO 430 KM = 417 TO 429 KM

The thick, outer contour corresponds to the minimum I/N of –6 dB required to protect the airborne radar and defines the non-uniform area around the airborne radar station inside of which interference from FSS earth stations would exceed the protection criterion. It should be noted that the maximum line-of-sight distance is 390 km between an earth station and an aircraft at 8 500 m altitude assuming 4/3 earth radius. Recommendation ITU-R M.1730-1 lists parameters for five other radar systems operating in the 15.4-17.3 GHz band, designated as Systems 1 through 5. Systems 1 and 2 are airborne, System 3 is shipborne, and Systems 4 and 5 are ground-based. Table 13-9 describes these radar systems and their antenna pointing ranges.

TABLE 13-9 Radar Antenna Pointing Ranges

System Description Antenna horizontal scan type Antenna vertical scan type System 1: Search, track and ±45º to ±135º –10º to –50º ground-mapping radar (multi (mechanical) (mechanical) function) System 2: Search, track and ±30º 0º to –90º ground-mapping radar (multi (electronic, conical) (electronic, conical) function) System 3: Air surveillance, ±40º +30º/–10º landing aid, track while scan (mechanical) (mechanical) System 4: Surveillance 180º +22.5º/–33.75º (mechanical) (mechanical) System 5: Ground surveillance 360º Not applicable and track (continuous) System 6: Search, track and ±45º +5° to –45° ground-mapping (multi- (electronic) (electronic) function)

Rep. ITU-R S.2365-0 377

Reference antenna patterns were constructed for Systems 1 and 5 in accordance with Recommendation ITU-R M.1851 and the criteria specified in Table 5, Pattern Selection Table, of that recommendation. All three airborne platforms are assumed to be at an altitude of 8,500 meters above mean sea level for these analyses, and the Recommendation ITU-R P.452-14 propagation model was used for the ground based radar system calculations. Table 13-10 compares the results of running the analyses described above for all six radiolocation systems with respect to the potential sharing of the 15.4-17 GHz band with FSS (Earth-to-space) operations.

TABLE 13-10 Summary Results of Radar Systems 1 through 6 Sharing with FSS Uplinks

System 1 System 2 System 3 System 4 System 5 System 6

(Airborne) (Airborne) (Shipborne) (Ground) (Ground) (Airborne) VSAT: 416 to 427 to 269 to 198 to 238 to 423 to PSD = –42 dBW/Hz 418 km 457 km 342 km 275 km 332 km 441 km Wideband: 366 to 423 to 238 to 167 to 206 to 420 to PSD = –49 dBW/Hz 420 km 437 km 320 km 244 km 303 km 431 km Point-to-Point: 353 to 422 to 233 to 163 to 201 to 417 to PSD = –50 dBW/Hz 424 km 437 km 323 km 240 km 298 km 429 km

The required separation distances to protect radar systems from FSS uplink transmissions extend beyond the earth station horizon for all three airborne systems, while significantly smaller distances are required to protect the ground-based radar systems.

13.2.1.3.3 Airborne Radar Interference into GSO Space Station Receiver Since the airborne radar antenna can vertically scan up to 5° above the horizontal plane, there will be times at which the radar antenna beam over its horizontal scanning range of ±45° can be pointing at or near a satellite in the geostationary satellite orbit as illustrated in Fig. 13-6. If the aircraft azimuth is within ±45 degrees of an azimuth at which the GSO appears within 5 degrees of the horizon, the radar main beam will sweep across the GSO. During these periods, the space station receiver may receive levels of interference that exceed the interference threshold if the band is allocated to the FSS in the Earth-to-space direction.

378 Rep. ITU-R S.2365-0

FIGURE 13-6 Intersection of Airborne Radar Sweep and GSO

Geostationary Satellite Orbit

Intersection of Radar Main Beam and GSO

Horizon RTaexdt ar Elevation Sweep: +5º to 0º

Horizontal Plane

RTaexdt ar Elevation Sweep: 0º to -45º

Radar Azimuth Swt eep: -45º to +45º x e T The G/T of a receiving space station in the GSO is required to calculate the I/N produced by an airborne radar into a GSO satellite receiver. A partial survey of the most recent notifications of satellite networks listed in the ITU-R’s Space Network Systems (SNS) database was conducted over a range of longitudes in the three ITU Regions. A range of typical values was assumed for this analysis in terms of the highest (17 dBK–1), median (7 dBK–1) and lowest (–6 dBK–1) G/T values as indicated from the data in Table 13-11.

TABLE 13-11 GSO Space Station G/T Values

GSO arc Networks Maximum G/T Median G/T Minimum G/T Region examined considered Case 4(a) Case 4(b) Case 4(c) 1 –5° – 35° East 49 16.9 dBK–1 9.37 dBK–1 –6.61 dBK–1 2 –120° – 75° East 43 13.22 dBK–1 4.27 dBK–1 –6.6 dBK–1 3 70° – 130° East 73 22.01 dBK–1 7.59 dBK–1 –6.13 dBK–1 Typical values assumed for analysis 17 dBK–1 7 dBK–1 –6 dBK–1

Calculations of interference into an earth station receiver include an On-Tune Rejection (OTR) factor as specified in Recommendation ITU-R M.1461-1 that depends on the radar chirp bandwidth and pulse duration and the earth station receiver bandwidth. Figure 13-7 plots the dependency of OTR on the radar pulse duration T and the FSS signal bandwidth for the System 6 chirp bandwidth of 1,850 MHz. Rep. ITU-R S.2365-0 379

FIGURE 13-7 On-Tune Rejection Curves for System 6 Radar System

Table 13-12 presents the OTR for each of the three types of FSS transmissions listed in Table 13-8 for the shortest and longest pulse durations, , used by Radar System 6.

TABLE 13-12 On-Tune Rejection Factors for Typical FSS Transmission Types

FSS Bandwidth On-Tune Rejection (dB) FSS Transmission Type (MHz)  = 0.05 s  = 50 s VSAT 0.58 50.41 20.41 Wideband 30.84 15.90 0.00 Point-to-Point 2.94 36.32 6.32

Link calculations are presented in Table 13-13 for the VSAT,  = 0.05 s, and the Wideband,  = 50 s, cases, which represent the cases with the highest and lowest OTR values, respectively. The resulting I/N calculated under free space propagation conditions is compared to an FSS space station I/N threshold of –12.2 dB, corresponding to the ∆T of 6% for 100% of the worst month criterion of Recommendation ITU-R S.1432. As indicated in the Table, this I/N threshold is exceeded in 5 of the 6 examples presented in the Table.

380 Rep. ITU-R S.2365-0

TABLE 13-13 Calculation of interference from airborne radar into GSO space station receiver

Parameter High G/T Median G/T Low G/T Units Elevation angle 5 5 5 5 5 5 degrees GSO distance 41.127 41.127 41.127 41.127 41.127 41.127 km Frequency 17 17 17 17 17 17 GHz Free space loss 209.33 209.33 209.33 209.33 209.33 209.33 dB Radar power 500 500 500 500 500 500 watts Pulse duration 50 0.05 50 0.05 50 0.05 mseconds Chirp bandwidth 1850 1850 1850 1850 1850 1850 MHz Radar antenna gain 35.00 35.00 35.00 35.00 35.00 35.00 dBi Radar bandwidth 1850 1850 1850 1850 1850 1850 MHz GSO G/T 17.00 17.00 7.00 7.00 –6.00 –6.00 dBK–1 GSO bandwidth 30.84 0.58 30.84 0.58 30.84 0.58 MHz On tune rejection 0.00 50.41 0.00 50.41 0.00 50.41 dB I/N 23.57 –9.59 13.57 –19.59 0.57 –32.59 dB I/N threshold –12.2 –12.2 –12.2 –12.2 –12.2 –12.2 dB Additional discrimination 5.77 2.61 25.77 0.00 12.77 0.00 dB required

Figures 13-8(a) to 13-8(c) illustrate the impact of the OTR on the I/N at the satellite receiver by presenting I/N calculations as a function of the satellite channel bandwidth and pulse duration, T.

FIGURE 13-8(a) FIGURE 13-8(b) I/N for Satellite G/T = 17 dBK–1 I/N for Satellite G/T = 7 dBK–1

40 25

30 15

20 5

-5 T = 50 microsec

0 T = 50 microsec I/N at GSO Satellite (dB) Satellite GSO at I/N I/N at GSO Satellite (dB) Satellite GSO at I/N T = 5 microsec T = 5 microsec T = 0.5 microsec -15 -10 T = 0.5 microsec T = 0.05 microsec T = 0.05 microsec

-20 -25 0 5 10 15 20 25 0 5 10 15 20 25 Satellite Channel Bandwidth (MHz) Satellite Channel Bandwidth (MHz)

Rep. ITU-R S.2365-0 381

FIGURE 13-8(c) I/N for Satellite G/T = –6 dBK–1

-10

-20

T = 50 microsec I/N at GSO Satellite (dB) Satellite GSO at I/N T = 5 microsec -30 T = 0.5 microsec

T = 0.05 microsec

-40 0 5 10 15 20 25 Satellite Channel Bandwidth (MHz)

The sharp change in slope of the T = 50 s curve at around 7 MHz reflects the OTR dropping to 0 dB at this and greater bandwidths, and the I/N begins to decrease at this point as the noise power increases with increasing bandwidth for a constant interfering signal level. A similar situation occurs for the T = 5 s curve where the OTR drops to 0 dB at about 19 MHz and this curve merges into the T = 50 s curve. Since space station antennas in this portion of the spectrum are not normally pointed towards the earth’s limb where low elevation angles occur, there may be sufficient antenna discrimination towards the airborne radar to maintain the space station I/N below the I/N threshold even when an airborne radar main beam points directly at the GSO. Figure 13-9 presents the required GSO satellite antenna discrimination for each of the three cases in Table 13-12 as a function of the channel bandwidth for the worst case 50 s radar pulse duration.

FIGURE 13-9 Required Space Station Discrimination Towards the Earth’s Limb

40 G/T = 17 dB/K 35

25 G/T = 7 dB/K

20 Discrimination (dB) Discrimination 15

Required Satellite Antenna Antenna Satellite Required G/T = -6 dB/K

5 0 5 10 15 20 25 Satelllite Channel Bandwidth (MHz)

Table 13-14 compares the results of running the same analyses described above for all six radiolocation systems listed in Recommendations ITU-R M.1730-1 with respect to the potential sharing of the 15.4-17 GHz band with FSS (Earth-to-space) operations. Calculations of the I/N at the GSO satellite receiver are calculated for the highest and lowest OTR values derived from the radar

382 Rep. ITU-R S.2365-0 emission parameters specified in Recommendation ITU-R M.1730-1 and the range of VSAT channel bandwidths provided in Table 13-8 above.

TABLE 13-14 Space Station Antenna Discrimination Required for Radar Sharing With FSS Uplinks

Interference Path System 1 System 2 System 3 System 4 System 5 System 6 (Airborne) (Airborne) (Shipborne) (Ground) (Ground) (Airborne) High Space Station G/T 4.16 to 0.00 to 48.09 to 14.18 to 14.56 to 2.61 to (17 dBK–1) 7.09 dB 24.79 dB 60.34 dB 31.44 dB 31.81 dB 35.77 dB Median Space Station 0.00 to 38.09 to 4.18 to 4.56 to 0.00 to 0.00 dB G/T (7 dBK–1) 14.79 dB 50.34 dB 21.44 dB 21.81 dB 25.77 dB Low Space Station G/T 0.00 to 25.09 to 0.00 to 0.00 to 0.0 to 0.00 dB (–6 dBK–1) 1.79 dB 37.34 dB 8.44 dB 8.81 dB 12.77 dB

Significant amounts of satellite antenna discrimination may be required to protect GSO satellite receivers from radar emissions since antenna pointing restrictions on radar antennas are not practical. The normal satellite antenna gain roll-off towards the Earth’s limb for spot beams in this portion of the spectrum may be sufficient to protect GSO satellite receivers from emissions from radars whose antennas do not point above the horizontal plane. However, achieving the necessary satellite antenna discrimination may be problematic with respect to ground-based radars whose relatively high antenna pointing elevation angles may be close to or within the main beams of some GSO satellites.

13.2.1.4 Results of studies With respect to a potential allocation to the FSS (Earth-to-space), the analysis shows that in order to protect radiolocation stations operating in the 15.4-17.3 GHz band in all three ITU Regions, a separation distance of up to 420 km or more (not accounting for terrain obstruction) describes a non-uniform area around a radiolocation receiver where the protection criteria is exceeded. For fixed, ground-based radiolocations systems (as opposed to airborne radiolocations systems), the required separation distances may be reduced down to ranges between 5 to 53 km if the FSS earth station PSDs are reduced to values range from –55 dBW/Hz to –60 dBW/Hz, and if there are horizon obstruction losses. The receiver in the radiolocation system can either be fixed or mobile. When the radiolocation system moves, so does the associated non-uniform area. In order to ensure the protection for current and future radiolocation operations, the protection criteria within this non- uniform area must be met. In addition, since the main beams of such radiolocation systems can point toward the GSO, FSS space stations may be subject to unacceptable levels of interference over periods of time from radiolocation systems operating under the existing primary allocation in this band. This should be taken into account in developing any methods.

13.2.2 FSS (E-s) and ARNS This section presents a sharing study between proposed fixed-satellite service FSS (Earth-to-space) and ALS (aircraft landing system) in the aeronautical radio navigation service (ARNS) operating in 15.4-15.7 GHz band.

13.2.2.1 Characteristics of the Aircraft Landing Systems (ALS) The technical characteristics of aircraft landing systems (ALS) which operate in the 15.4-15.7 GHz band are descripted in Recommendation ITU-R S.1340 which deals with sharing between feeder links for the mobile-satellite service and the aeronautical radio navigation service. ALS characteristics are also described in Report ITU-R M.2170 which deals with sharing between ARNS and radiolocation systems planned to operate in the 15.4 to 17.3 GHz band. In addition, Report ITU-R M.2221 deals Rep. ITU-R S.2365-0 383 inter alia with sharing between MSS and ARNS within the band 15.4-15.7 GHz. Technical description of ALS is summarized in Report ITU-R M.2221 from Report ITU-R M.2170 and Recommendation ITU-R S.1340. The ALS system consists of azimuth and elevation transmitters, including separate azimuth and elevation antenna, located at the landing site. The receiver is located in the aircraft. The aircraft system receives coded transmissions on a number of selectable channels from the ground-based azimuth and elevation transmitters; it decodes the received signals for display on a cross-pointer indicator in the aircraft cockpit. A centre-line display of both elevation and azimuth on the cross-pointer indicator depicts the flight path the pilot must follow to line up accurately with the runway. By consecutively scanning through azimuth and elevation, the system provides continuous measurement of the lateral and vertical deviations of the aircraft in space from the optimum approach line. The aircraft receiver local oscillator (LO) is a crystal-controlled solid-state unit employing multipliers, amplifiers, and filters, which provide rejection of spurious signals. Filters in the detector circuit remove the IF component, so that only video is passed to the decoder. Variable service requirement for ALS require that the ground stations of this service are re-locatable and used at unspecified points.

TABLE 13-15 Aircraft landing systems characteristics in the 15.4-15.7 GHz band (ITU-R M.2170)

Characteristics Aircraft landing system Function Transmitter Receiver Platform type Located at the landing site Airborne platform Tuning range (GHz) 15.4-15.7 15.4-15.7 Modulation Pulse Not applicable Transmit peak power (W) 2 200 Not applicable Pulse width (s) 0.3 Not applicable Pulse rise/fall time (ns) 100/100 Not applicable Pulse repetition rate (pps) 3 334 Not applicable Maximum duty cycle 0.001 Not applicable Output device Magnetron Not applicable Antenna pattern type Beam Beam (assumed) Antenna gain (dBi) Az 31 El 26 4 Antenna elevation beamwidth (degrees)* ±20 hor 1.25 ver 30 Antenna azimuthal beamwidth (degrees)* Az 2 hor 6 ver 70 Antenna horizontal scan rate 5 Hz Not applicable Antenna horizontal scan type Sector Not applicable Antenna vertical scan rate 5 Hz Not applicable

384 Rep. ITU-R S.2365-0

TABLE 13-15 (end)

Characteristics Aircraft landing system Function Transmitter Receiver Antenna vertical scan type Sector Not applicable Antenna 1st side-lobe level 20 dB down from the main 20 dB minimum lobe peak (assumed)** Antenna height (m) Ground level 1 000 (typical landing sequence initiation) 1st/2nd receiver IF –3 dB bandwidths (MHz) 15 Receiver noise figure (dB) 10 Minimum discernible signal (MDS) (dBm) –72 * There are two antennae systems one for azimuth and one for elevation. ** The receiver antenna 1st side-lobe level needs to be verified.

FIGURE 13-10 Normalized antenna elevation pattern for ALS (15 GHz band)

Rep. ITU-R S.2365-0 385

TABLE 13-16 Summary of technical characteristics according to Recommendation ITU-R S.1340

System Units Aircraft landing system (ALS) Reference ITU-R S.1340 (1997) Annex 1 section 2 Frequency range GHz 15.4-15.7 Peak power dBW 38 Antenna pattern ITU-R S.1340 (1997) Transmit antenna gain dBi Az 33 El 28 Nominal 3 dB beamwidth degree Az (6.5° Vertical, 2° Horizontal) El (1.3° Vertical, 40° Horizontal) Receiver antenna gain dBi 8 (on the landing aircraft) Maximum side-lobe level below dB peak gain Nominal 3 dB Receive antenna degree Omni directional pattern beamwidth Antenna polarization Horizontal and vertical Vertical tilt range degree Omni directional Maximum horizontal scan range degree Omni for receive antenna directional Receiver IF bandwidth MHz 3 Noise figure dB 8

13.2.2.2 FSS earth station characteristics Table 13-17 values, taken from Annex 10 of the WP 4A Chairman’s Report, Document 4A/343 (Chapter 13.2.1.3.1), presents the characteristics of the FSS used in this analysis.

TABLE 13-17 FSS earth stations technical characteristics

Earth Station Antenna size (m) 0.6 0.9 1.2 2.4 6 Typical gain (dBi) 36.7 40.2 42.7 48.7 56.6 Typical 3 dB beamwidth at 14 GHz (°) 2.6 1.8 1.3 0.7 0.3 PSD at antenna port (dBW/Hz) –52 –52 –42 –42 –42 Off-axis radiation pattern S.1855 S.1855 S.1855 S.580 S.580 Off-axis power limits Rec. ITU-R S.728

386 Rep. ITU-R S.2365-0

13.2.2.3 Interference scenarios The interference scenarios to be considered are: − Potential interference from FSS earth station into ALS receivers. − Potential interference from ALS transmitters into FSS satellite. 13.2.2.4 Sharing between FSS (earth to space) and ALS receivers This study examines the compatibility of the transmitting FSS earth station and the ALS receiver. ALS use a ground based transmitter positioned at the aircraft landing site. The system consists of azimuth and elevation transmitters, including separate azimuth and elevation antennas, located at the landing site. The receiver is located in the aircraft. The aircraft system receives coded transmissions on a number of selectable channels from the ground-based azimuth and elevation transmitters; it decodes the received signals for display on a cross-pointer indicator in the aircraft cockpit. The methodology and parameters used here to address interference between proposed FSS earth station and incumbent ALS is based on Recommendation ITU-R S.1340 which deals with sharing between feeder links for the mobile-satellite service and the aeronautical radionavigation service. The ALS interference criteria and aircraft maximum altitude based also values given in Recommendation ITU-R S.1340. The value of I/N = –10 dB is used for the protection of ALS, and the aircraft altitude is 7.6 km. The main technical parameters of transmitting FSS earth stations are shown in Table 13-17. Example calculation is made to the earth station which antenna gain is assumed to 42.7 dBi and PSD at antenna port –42 (dBW/Hz). Earth station elevation angle is assumed to be 10 degree. Maximum e.i.r.p. density of the earth station toward the horizon is 25 dB (W/MHz)) 1) Calculation of the total radio line-of-sight distance (km). According to expression in Recommendation ITU-R S.1340: 0.5 0.5 Dfsl = (2 · 8 500 km· 7.6 km)  (2 · 8 500 km · 0.01 km) = 372.5 km. 2) Calculation of free space loss computed for Dfsl. Basic transmission losses  due to line-of-sight propagation and due to over-the-horizon propagation as well as the distance corresponding to these losses are calculated by expressions in Rec. ITU-R S.1340:

Lfsl = 20 log (15530 MHz)  20 log (372.5 km)  32.4 = 167.7 dB.

Loth = 25 dB(W/MHz)  168.6 – 167.7 dB  (-22.7 dB) – (–10 dB) = 13.2 dB. Using Recommendation ITU-R S.1340 Table 1 and its extrapolation formula 8 we can calculate over- the-horizon distance Doth as follows:

Doth = 25(13.2 dB / 24 dB) = 13.7 km 3) Then coordination distance Dc according to Recommendation ITU-R S.1340, necessary to ensure ALS receivers protection against interference:

Dc = 372.5 km + 13.7 km + 100 km = 486.2 km Coordination distances for Table 13-17 FSS earth stations have been calculated and the required coordination distances vary between 476-486 km according to Recommendation ITU-R S.1340. If the earth station elevation angle is less than 10 degrees even greater coordination distances are needed. It should be noted that according to this Recommendation, the minimum separation distance is equal to 472 km even in absence of FSS (Earth-to-space) emission. Such FSS (Earth-to-space) emission only increase this distance by less than 14 km. Rep. ITU-R S.2365-0 387

13.2.2.5 ALS Interference into GSO space station receiver If the band is allocated to the FSS in the earth-to-space direction, ALS can cause interference to a GSO space station receiver. The worst-case situation is when the FSS satellite sees the ALS transmitter at a low elevation, aligned with the maximum antenna gain of the ALS transmitter. Annex 10 of the WP 4A Chairmanʼs Report, Document 4A/343 (Chapter 13.2.1.3.3) presented typical G/T values to GSO space station. These are 17 dBK–1 (highest), 7 dBK–1 (median) and –6 dBK–1 (lowest). Interference calculations are presented in table for each of these values. A satellite channel bandwidth is assumed to be 15 MHz. It is the same as the ALS –3 dB IF bandwidth. The resulting I/N calculated under free space propagation conditions is compared to an FSS space station I/N threshold of −12.2 dB, corresponding to the ∆T of 6% for 100% of the worst month criterion of Recommendation ITU-R S.1432. As indicated in the Table 13-18, this I/N threshold is exceeded in all three cases presented in the table considering the worst case situation (i.e. ALS TX station located exactly in the line of sight of the GSO FSS and the ALS RX station). However, taking into account the nominal 3 dB beamwidths of ALS antenna and the fact that ALS antenna scans horizontally and vertically through the required coverage volume, transmitting ALS station can cause interference to satellite(s) at any time and also when it is not pointing directly towards the satellite. Therefore satellite antenna discrimination up to 42 dB considering sateliite GSS G/T value of 17 dB is required to protect GSO satellite receivers from ALS emissions since antenna pointing restrictions on ALS antennas-due to the nature of ALS service – not a feasible solution.

TABLE 13-18 Calculation of interference from ALS transmitter into GSO space station receiver in the worst case situation

Parameter Satellite G/T value (dBK–1) 17 7 –6 Elevation angle (degrees) 5 5 5 Distance to GSO (Km) 41 115 41 115 41 115 Frequency (GHz) 15.7 15.7 15.7 Free Space Loss (dB) 208.6 208.6 208.6 ALS transmitter peak power (dBW) 33.4 33.4 33.4 ALS Antenna Gain (dBi) 31 31 31 ALS Bandwidth (MHz) 15 15 15 Satellite Bandwidth (MHz) 15 15 15 I/N (dB) 29.4 19.8 6.8 I/N threshold (dB) –12.2 –12.2 –12.2 Additional Discrimination Required (dB) 42 32 19

13.2.2.6 Summary of study The band 15.4-15.7 GHz is allocated to the Aeronautical radio navigation systems on a primary basis in all three ITU Regions. In accordance with RR No. 4.10, Member States recognize that the safety aspects of radio navigation and other safety services require special measures to ensure their freedom from harmful interference; it is necessary therefore to take this factor into account in the assignment and use of frequencies. With respect to proposed allocation to the FSS (Earth-to-space), the study shows that a separation distance of up to 486 km is required in order to protect ALS receivers from transmitting FSS earth

388 Rep. ITU-R S.2365-0 stations according to Recommendation ITU-R S.1340. It should be noted that according to this Recommendation, the minimum separation distance is equal to 472 km even in absence of FSS (Earth-to-space) emission. Such FSS (Earth-to-space) emission only increase this distance by less than 14 km. ALS transmitter can also cause interference to a GSO space station receiver up to 42 dB above the protection criterion considering the worst case situation (i.e. ALS Tx station located exactly in the line of sight of the GSO FSS and the ALS Rx station and a satellite FSS G/T value of 17 dB). However, taking into account the nominal 3 dB beamwidths of ALS antenna and the fact that ALS antenna scans horizontally and vertically through the required coverage volume, transmitting ALS station can cause interference to satellite(s) at any time and also when ALS is not pointing directly to satellite. Based on the results interference from FSS (Earth-to-space) exceed the protection criteria level of ALS receiver without specific mitigation techniques implemented to FSS earth station. Morever, FSS receiving space stations could be subject to interference up to 42 dB from existing ALS in this band.

13.2.3 FSS (E-s) and Non-GSO FSS (E-s) No sharing studies were submitted to the ITU-R for GSO FSS (E-s) satellite systems and Non-GSO FSS in the band 15.4-15.7 GHz.

13.2.4 FSS (E-s) and RAS in the adjacent frequency band The emissions in the frequency band 15.4-15.7 GHz can cause interference to RAS receive station operating in the adjacent frequency band 15.35-15.4 GHz. In accordance with Recommendation ITU-R RA.769 the interference at RAS receiver input in 50 MHz shall not exceed –202 dBW (−219 dBW/MHz accordingly) in the frequency band 15.35-15.4 GHz. Past studies showed that such high requirements for the out-of-band emissions can be met only by systems using the certain types of the location signals. Taking into account that the FSS systems do not use such signals the sharing of the FSS (E-s) with RAS in the adjacent frequency band should be further studied.

13.2.5 FSS (s-E) and RLS 13.2.5.1 Airborne radar interference into FSS Earth station receiver If the 15.4-17 GHz band is used for FSS downlinks in Region 1, then existing airborne radars may cause interference into earth station receivers. Recommendation ITU-R M.1730-1 lists the parameters of 6 radiolocation systems in the 15.4-17.3 GHz band to be used for assessing the feasibility of sharing in this band. A minimum aggregate I/N ratio of –6 dB for signals from other services with high-duty cycle (e.g. continuous wave, binary phase shift keying, quaternary phase shift keying, noise-like, etc.), which includes the FSS, is required to protect the operations of these systems. Detailed analyses are presented below for the airborne radar system listed as System 6 in that recommendation. The relevant parameters of this system are provided in § 13.2.1.3 above. Summary results of performing the same analyses for Systems 1 through 5 listed in Recommendation ITU-R M.1730-1 are also presented in Table 13-21 below. Calculations of interference into an earth station receiver include an On-Tune Rejection (OTR) factor as specified in Recommendation ITU-R M.1461-1 that depends on the radar chirp bandwidth and pulse duration and the earth station receiver bandwidth. Figure 13-7 of § 13.2.1.3.3 plots the dependency of OTR on the radar pulse duration T and the earth station signal bandwidth for the System 6 chirp bandwidth of 1,850 MHz. The worst case interference will occur when there is mainbeam-to-mainbeam antenna coupling with free space propagation. Figure 13-11 presents the calculated I/N for the longest and shortest radar Rep. ITU-R S.2365-0 389 pulse durations for three FSS transmission types and their associated bandwidths indicated in Table 13-8 of § 13.2.1.3.1.

FIGURE 13-11 Worst Case (Mainbeam Coupling) I/N into VSAT Receiver

PULSE DURATION = 50 SECONDS PULSE DURATION = 0.05 SECONDS

Figure 13-12 is a plot of the I/N produced by an airborne radar into a FSS receivers with a receiving system noise temperature of 200 K for the shortest and longest pulse durations, , and the following assumptions: – the earth station gain towards the aircraft is the gain at the minimum off-axis angle between the geostationary satellite orbit and the aircraft, which is typically significantly less than the main beam gain; – the radar antenna is pointing directly at the earth station; and – the Recommendation ITU-R P.528-3 propagation model is used to calculate the 20% probability path loss without taking terrain into account.

390 Rep. ITU-R S.2365-0

FIGURE 13-12 I/N contour plots of Airborne Radar Interference into FSS Receivers

An FSS I/N threshold of –10 dB that can be exceeded for 20% of any month is assumed based on Recommendation ITU-R S.1432, and the distances at within which this threshold is exceeded is indicated in Table 13-19.

TABLE 13-19 Separation Distances Within Which the FSS I/N Threshold Is Exceeded

FSS Transmission Type  = 0.05 s  = 0.50 s VSAT 27 to 153 km 302 to 410 km Wideband 358 to 414 km 421 to 432 km Point-to-Point 127 to 318 km 417 to 423 km

Rep. ITU-R S.2365-0 391

It is clear that there is a large variation in the OTR over the range of pulse durations employed by this radar and potential earth station bandwidths. To illustrate these effects, required separations based on the Recommendation ITU-R P.528-3 propagation model are presented in Table 13-20 for several combinations of T, FSS receiver IF bandwidth, and the combined antenna coupling (Gt + Gr) between the airborne radar and earth station antennas.

TABLE 13-20 Required separations based on radar pulse duration and total antenna Coupling

FSS Earth station bandwidth 0.1 MHz 1 MHz 2.5 MHz 10 MHz 25 MHz

T = 50 ms; Gt + Gr = 10 dBi 180 km 300 km 341 km 359 km 318 km

T = 0.05 ms; Gt + Gr = 10 dBi 98 km 180 km 234 km 255 km 200 km

T = 50 ms; Gt + Gr = 0 dBi 10 km 36 km 54 km 98 km 138 km

T = 0.05 ms; Gt + Gr = 0 dBi 3 km 10 km 19 km 36 km 54 km

Figure 13-13 illustrates the relationship between the airborne radar and earth station off-axis angles needed to achieve a total antenna coupling of 10 dBi or 0 dBi. The reference antenna radiation patterns specified in Table 13-8 of § 13.2.1.3.1 for a 1.2 m diameter VSAT antenna, and Fig. 13-3 of § 13.2.1.3 for the radar antenna, were used in calculating the off-axis gains and associated angles for the earth station and radar antennas, respectively, in the Figure.

FIGURE 13-13 Antenna off-axis angles for 10 or 0 dBi mutual antenna Coupling 14

8 Axis Angle (degrees) Angle Axis - 6

4 Radar Off Radar

2 0 5 10 15 20 25 30 35 40 45 50 Earth Station Off-Axis Angle (degrees) Table 13-21 compares the results of running the same analyses described above for all six radiolocation systems listed in Recommendation ITU-R M.1730-1 with respect to the potential sharing of the 15.4-17 GHz band with FSS (space-to-Earth) operations. Results are presented for radar interference into the VSAT,  = 0.05 s, and the Wideband,  = 50 s, transmission cases, which represent the highest and lowest OTR values, respectively, as indicated by Table 13-12 of § 13.2.1.3.3 above. The Recommendation ITU-R P.452 propagation mocel is used to calculate the 20% probability path loss without taking terrain into account.

392 Rep. ITU-R S.2365-0

TABLE 13-21 Summary results of radar Systems 1 through 6 sharing with FSS downlinks

System 1 System 2 System 3 System 4 System 5 System 6 Interference Case (Airborne) (Airborne) (Shipborne) (Ground) (Ground) (Airborne) VSAT Transmission 14-133 km 46-200 km 42-53 km 2-20 km 60-74 km 27-153 km SAT Transmission Wideband 340-420 km 423-434 km 151-298 km 35-50 km 137-279 km 421-432 km Transmission ideband Transm.

13.2.5.2 FSS GSO space station interference into airborne radar receiver Since the airborne radar antenna can vertically scan up to 5° above the horizontal plane, there will be times at which the radar antenna beam over its horizontal scanning range of ±45° can be pointing at or near a satellite in the geostationary satellite orbit. If the aircraft azimuth is within ±45° degrees of an azimuth at which the GSO appears within 5° of the horizon, the radar main beam will sweep across the GSO. During these periods, the radar receiver may receive levels of interference that exceed the interference threshold if the band is allocated to the FSS in the space-to-earth direction. Table 13-22 presents the results of link calculations of the estimated I/N that could occur under these conditions. Three cases are examined. Cases 3(a) and 3(b) assume that the radar encounters interference at a pfd currently specified Table 21-4 of the Radio Regulations in the 15.43-15.63 GHz and 17.7-19.3 GHz bands, respectively. The WP 4A model assumes the satellite e.i.r.p. density in Table 13-8 of § 13.2.1.3.1 above.

TABLE 13-22 Interference from GSO FSS satellite into airborne radar receiver

Parameter pfd Limited WP4A Model Units 15.43- 17-7- FSS 15.63 GHz 19.3 GHz Deployment Case pfd Limit pfd Limit Model PSD Elevation Angle 5 5 5 degrees GSO distance 41,127 41,127 41,127 km Satellite e.i.r.p. (PSD = –20 dBW/Hz) ------40.00 dBW/MHz Power Flux Density –115.00 –127.00 –123.27 dBW/m^2-MHz Frequency 17,000 17,000 17,000 MHz Area of an Isotropic Antenna –46.06 –46.06 –46.06 dB(m^2) Radar Antenna Gain 35 35 35 dBi Interference Level at Radar –126.06 –138.06 –134.33 dBW/MHz Radar Noise Figure 5 5 5 dB

Rep. ITU-R S.2365-0 393

TABLE 13-22 (end)

Parameter pfd Limited WP4A Model Units Radar Noise Power –138.98 –138.98 –138.98 dBW/MHz I/N 12.92 0.92 4.64 dB I/N Criterion –6.00 –6.00 –6.00 dB Additional Discrimination Required 18.92 6.92 10.64 dB Required Radar Off-Axis Angle 3.57 2.35 2.84 degrees Earth Central Angle (Inner) 72.83 74.02 73.54 degrees Earth Central Angle (Outer) 79.87 78.66 79.15 degrees Annular Width 7.04 4.64 5.61 degrees Annular distance 784 516 625 km Time in Annular Ring @ 800 km/hr 59 39 47 minutes

In all three cases, the –6 dB I/N threshold is exceeded when the airborne radar main beam intersects the GSO and the pfd exceeds –134 dB(W/m2-MHz). The required off-axis discrimination angle to achieve a –6 dB I/N for each case is calculated in Table 13-10 using the radar antenna pattern in Fig. 13-3. The off-axis antenna pointing angles correspond to two elevation angles to the GSO, one above and the other below 5°. The locus of points on the earth’s surface with the specified elevation angle to a particular point on the GSO is defined by a circle on the earth’s surface with the Earth central angle indicated in Table 13-10. The area within which the I/N threshold can be exceeded for Case 3(a) is an annulus bounded by two rings corresponding to elevation angles of 5° ± 3.57°, as illustrated in Fig. 13-14 for a GSO satellite located at 0° East Longitude.

FIGURE 13-14 Example of airborne radar locations exceeding I/N threshold for Case 3(a)

This annulus assumes that the airborne radar antenna is fixed with an elevation angle of 5°, so the corresponding annulus then. As can be seen, an airborne radar in Region 2 can experience an I/N exceeding the –6 dB threshold from a Region 1 FSS downlink. For an aircraft travelling at 800 km/h, the I/N threshold can be exceeded for a period lasting between 39 and 59 minutes when the aircraft is flying in a direction normal to the annulus, and for longer periods when flying in a direction non- normal to the annulus.

394 Rep. ITU-R S.2365-0

Table 13-23 compares the results of running the same analyses described above for all six radiolocation systems listed in Recommendation ITU-R M.1730-1 with respect to the potential sharing of the 15.4-17 GHz band with FSS (space-to-Earth) operations.

TABLE 13-23 Summary results of radar Systems 1 through 6 sharing with FSS downlinks

System 1 System 2 System 3 System 4 System 5 System 6 Interference Path (Airborne) (Airborne) (Shipborne) (Ground) (Ground) (Airborne) Case 3: Allowable –110 dBW/ –109 dBW/ –142 dBW/ –136 dBW/ –98 dBW/ –134 dBW/ GSO Satellite pfd m2-MHz m2-MHz m2-MHz m2-MHz m2-MHz m2-MHz into Radar

The current pfd limits on GSO satellites in the bands in the vicinity of 15.4-17 GHz are sufficient to protect Systems 1, 2 and 5 since their antennas do not point above the horizontal plane. However, more restrictive pfd limits are required to protect Systems 3, 4 and 6 whose antennas can point above the horizontal plane, and, in the case of Systems 2 and 3, at elevation angles up to 30 and 22.5 degrees, respectively.

13.2.5.3 Summary of studies With respect to a potential allocation to the FSS (space-to-Earth) in Region 1, the analysis shows that in order to protect FSS receiving earth stations in the 15.4-17 GHz band from radiolocation system transmissions, a separation distance of up to 435 km (not accounting for terrain obstruction) describes a non-uniform area around a FSS receiving earth station receiver where the protection criteria is exceeded. In addition, since the main beams of such radiolocation systems, including those located in Region 2 or 3, may point at the GSO, radiolocation system receivers may be subject to unacceptable levels of interference over periods of time without implementation of mitigation technique. This study determined that a pfd of –142 dBW/m2-MHz would protect radiolocation system receivers, which is more restrictive than pfd limits applicable in nearby bands. This should be taken into account in developing any methods.

13.3 Summary of studies for the band 15.4-15.7 GHz WRC-12 agreed on a primary allocation in the 15.4-15.7 GHz band for the radiolocation service. The studies in the ITU-R that led up to this decision focus synthetic aperture radar (SAR) on an aircraft. The band 15.4-15.7 GHz is allocated to ARNS on a primary basis and provision RR No. 4.10 (addressing safety-related services) applies. One study shows that separation distances up to 486 km is required to ensure protection between the FSS earth station (Earth-to-space) and ARNS receiver considering worst case situation (i.e. FSS earth station antenna pointing towards the ARNS receiver), according to Recommendation ITU-R S.1340 that was used in this study. Separation distances will be lower considering earth station configurations that reduce e.i.r.p. towards ARNS receiver. e.g. additional antenna discrimination between FSS earth station antenna and ARNS receiving antenna. Furthermore, if receiving GSO satellite is not having sufficient – in the worst case when the ARNS antenna is pointing towards the GSO, up to 42 dB – antenna discrimination, receiving GSO satellite could be subject to interference from existing ARNS transmitters.With respect to RLS airborne systems, one study shows that separation distances of 420 km (not accounting for terrain obstruction) would be needed to ensure protection between the FSS and RLS airborne systems operating in this band. Moreover, if FSS receiving space stations is not having sufficient antenna Rep. ITU-R S.2365-0 395 discrimination at low elevation angles, these may be subject to interference from existing RLS airborne systems in this band. Another study shows that for fixed, ground-based RLS systems (as opposed to airborne RLS systems) the required separation distances may be reduced down to ranges between 5 to 53 km if the FSS earth station PSDs are reduced to values range from –55 dBW/Hz to –60 dBW/Hz, and if there are horizon obstruction losses. The receiver in the radiolocation system can either be fixed or mobile. With respect to RLS ground-based systems into FSS space station receiving antennas, one study shows that an antenna discrimination of up to 60 dB may be required. Concerning FSS (space-to-Earth), pfd limits would be required to protect existing RLS systems operating in this band. Sharing studies between ARNS and FSS(space-to-Earth) has not been conducted.

14 Frequency band 15.7-16.6 GHz The allocations of this band in RR Article 5 are shown below.

TABLE 14-1 Excerpts from RR Article 5 on allocation to services in 15.7-16.6 GHz

Allocation to services Region 1 Region 2 Region 3 15.7-16.6 RADIOLOCATION 5.512 5.513

5.512 Additional allocation: in Algeria, Angola, Saudi Arabia, Austria, Bahrain, Bangladesh, Brunei Darussalam, Cameroon, Congo (Rep. of the), Costa Rica, Egypt, El Salvador, the United Arab Emirates, Eritrea, Finland, Guatemala, India, Indonesia, Iran (Islamic Republic of), Jordan, Kenya, Kuwait, Lebanon, Libya, Malaysia, Mali, Morocco, Mauritania, Montenegro, Nepal, Nicaragua, Niger, Oman, Pakistan, Qatar, Syrian Arab Republic, the Dem. Rep. of the Congo, Serbia, Singapore, Somalia, Sudan, South Sudan, Tanzania, Chad, Togo and Yemen, the band 15.7-17.3 GHz is also allocated to the fixed and mobile services on a primary basis. (WRC-12) 5.513 Additional allocation: in Israel, the band 15.7-17.3 GHz is also allocated to the fixed and mobile services on a primary basis. These services shall not claim protection from or cause harmful interference to services operating in accordance with the Table in countries other than those included in No. 5.512.

14.1 Review of Recommendations/Reports A list of relevant Recommendations and Reports that may be useful for sharing studies is in Table 14-2.

396 Rep. ITU-R S.2365-0

TABLE 14-2 Summary of relevant Recommendations that may be useful for sharing studies in the band 15.7-16.6 GHz

Service Relevant Recommendations Radiolocation Recommendation ITU-R M.1730 Recommendation ITU-R M.1461 Recommendation ITU-R M.1851 Report ITU-R M.2170 Fixed Recommendation ITU-R F.699 Recommendation ITU-R F.758 Recommendation ITU-R F.1107 Recommendation ITU-R F.1245 Recommendation ITU-R F.1333 Recommendation ITU-R F.1336 Recommendation ITU-R F.1777 Mobile Recommendation ITU-R M.1824

14.2 Sharing studies for the band 15.7-16.6 GHz 14.2.1 FSS (E-s) and radiolocation (RLS) See also § 13.2.1. This section reviews studies concerning sharing between FSS (Earth-to-space) and the radiolocation service (RLS) in the 15.7-16.6 GHz band. The band 15.7-16.6 GHz is used by many different types of radars including land-based, transportable, shipboard and airborne platforms. Radiolocation functions performed in the band include airborne and surface search, surface surveillance, ground-mapping, terrain-following, maritime and target-identification. Radar operating frequencies can be assumed to be uniformly spread throughout each radar’s tuning range. The major radiolocation radars operating or planned to operate in the band 15.7-16.6 GHz are primarily for detection of airborne objects and some are used for ground mapping. They are required to measure target altitude, range, bearing, and form terrain maps. Some of the airborne and ground targets are small and some are at ranges as great as 300 nautical miles (556 km), so these radiolocation radars must have great sensitivity and must provide a high degree of suppression to all forms of clutter return, including that from sea, land and precipitation. Some of the radars are used as the airport surveillance detection equipment (ASDE-3) to provide a tool to enhance the situational awareness of air traffic controllers in an effort to reduce runway incursions and aircraft collisions. These radars provide non-cooperative aeronautical surveillance including detection and position information for all aircraft and vehicles on the airport movement area.

14.2.1.1 RLS characteristics and protection criteria Recommendation ITU-R M.1730 recommends: – that the technical and operational characteristics of the radiolocation radars described in Annex 1 should be considered as representative of those operating or planned to operate in the band 15.4-17.3 GHz; Rep. ITU-R S.2365-0 397

– that an I/N of –6 dB, should be used as the required protection level for the portions of the 15.4-17.3 GHz band where there is a radiolocation allocation and that this represents the net protection level if multiple interferers are present; – that in the case of pulsed interference, the criteria should be based on a case-by-case analysis taking into account the undesired pulse train characteristics and, to the extent possible, the signal processing in the radar receiver. Procedures and methodologies to analyse compatibility between radars in the radiodetermination service and systems in other services are contained in Recommendation ITU-R M.1461. The technical parameters of 6 representative radiolocation radars operating or planned to operate worldwide in the frequency band 15.4-17.3 GHz are presented in Table 1 of Recommendation ITU-R M.1730-1. The sharing study in this section only considers the compatibility between FSS (E-s) and radiolocation system 5 in the 15.7-16.6 GHz band and the relevant technical characteristics of system 5 is listed in Table 14-3.

TABLE 14-3 Characteristics of radiolocation radar, System 5, in the 15.4-17.3 GHz band

Characteristics System 5 Function Ground surveillance & track Platform type Ground-based high power Tuning range, GHz 15.7-16.2 Modulation Pulse, frequency hopping Pulse width, ns 36 Pulse repetition rate, pps 20 000 Max duty cycle 0.00072 Antenna gain, dBi 43 Antenna elevation beamwidth, degrees 1.6 Antenna azimuth beamwidth, degrees 0.25 Antenna rotation rate, deg/s 360 Antenna 1st side-lobe level 23 dBi @ 1.6° Antenna height, m 100 Receiver IF –3 dB bandwidth, MHz 50 Rx noise figure, dB 3.97

14.2.1.2 Study #1: FSS (E-s) and RLS system 5 – sharing study and results The FSS ES antenna gain patterns at 15.777 GHz, specified to follow Recommendation ITU-R BO.1213 for main beam antenna gain, for five different FSS ES antenna gains are plotted in Fig. 14-1 as function of the off-axis angle.

398 Rep. ITU-R S.2365-0

FIGURE 14-1 FSS ES main-lobe antenna gain patterns at 15.777 GHz (ITU-R BO.1213)

FSS ES Main-Lobe Antenna Gain (ITU-R BO.1213) at 15.777 GHz 70 VSAT G = 37.2 dBi max VSAT G = 50.5 dBi 60 max Wide G = 51.7 dBi max Wide G = 57.2 dBi max 50 Wide G = 60.8 dBi max

FSS gain, dBi ESantenna main-lobe 20

10 -5 -4 -3 -2 -1 0 1 2 3 4 5 Off-axis angle, deg

The ASDE-3 antenna elevation gain patterns (dBi) are depicted in Fig. 14-2 as function of the offset elevation angle (degrees), based on test data10.

FIGURE 14-2 Measured ASDE-3 antenna elevation gain patterns

Measured ASDE-3 Antenna Elevation Pattern 44

Gain, Gain, dBi

26 0 5 10 15 20 25 Offset elevation angle, deg

The locations of system 5 (ASDE-3) in United States are shown in Fig. 14-3.

10 F. LaRussa, ASDE-3 Antenna Development and Test, FAA-RD-81-43, Cambridge, MA: US Department of Transportation, Transportation Systems Center, April 1981. Rep. ITU-R S.2365-0 399

FIGURE 14-3 Locations of system 5 (ASDE-3) in 15.7-16.6 GHz

120 W 100 W 80 W 50 N

40 N

30 N

System parameters required for the determination of coordination distance for a transmitting FSS ES sharing with RLS receiving terrestrial station in the 13.75-14.3 GHz frequency band in Table 7b of RR Appendix 7 will be used to determine the coordination area between FSS ES and RLS system-5 receiving terrestrial station in the 15.7-16.6 GHz frequency band. Since the signal emission from FSS earth station is continuous, an I/N ratio of –6 dB (Recommendation ITU-R M.1730-1) is used as the required protection level for systems operating in the 15.7-16.6 GHz band and this level represents the net protection level if multiple interferers are present. Since the ASDE-3 radars rotate 60 revolutions per minute or 360o per second, Fig. 14-4 shows the required coordinate/separation areas (using ITU-R P.452-14 with p = 0.01%) that are required to protect the RLS system 5 stations from interference due to FSS earth stations (FSS ES2 and FSS ES3), where the maximum coordination distance and the azimuth radial for each system-5 site are shown as a “blue” line to the site. Note that some close-by ASDE-3 sites (northern Virginia and southern New York) are not included in the simulation.

400 Rep. ITU-R S.2365-0

FIGURE 14-4

VSAT ES (PSD = –42 dBW/Hz, GT = 43.5 dBi) & ASDE-3 – Coordination Areas

120 W 100 W 80 W 50 N

40 N

xPSD = -42 dBW/Hz xG = 43.5 dBi rG = 44 dBi 30 N p = 0.01% Max Dist = 304 km

FIGURE 14-5

FSS WB ES (PSD= –49 dBW/Hz, GT = 52 dBi) & ASDE-3 – Coordination Areas

120 W 100 W 80 W 50 N

40 N

xPSD = -49 dBW/Hz xG = 52 dBi rG = 44 dBi 30 N p = 0.01% Max Dist = 286 km

Large coordination areas in order of 304 km are required to protect RLS system-5 from the emissions of FSS ES. These results should be taken into account should a primary FSS allocation in the Earth- to-space direction be considered in this frequency band.

14.2.1.3 Additional Studies See § 13.2.1.

14.2.2 FSS (E-s) and fixed No sharing studies were submitted to the ITU-R for FSS (E-s) satellite systems and fixed service in the band 15.7-16.6 GHz. Rep. ITU-R S.2365-0 401

14.2.3 FSS (E-s) and mobile No sharing studies were submitted to the ITU-R for FSS (E-s) satellite systems and mobile service in the band 15.7-16.6 GHz.

14.2.4 FSS (s-E) and radiolocation See § 13.2.5.

14.3 Summary of studies for the band 15.7-16.6 GHz With respect to RLS airborne systems, one study shows that separation distances of 420 km (not accounting for terrain obstruction) would be needed to ensure protection between the FSS and RLS airborne systems operating in this band. Moreover, if FSS receiving space stations is not having sufficient antenna discrimination at low elevation angles, these may be subject to interference from existing RLS airborne systems in this band. Another study shows that for fixed, ground-based RLS systems (as opposed to airborne RLS systems) the required separation distances may be reduced down to ranges between 5 to 53 km if the FSS earth station PSDs are reduced to values range from –55 dBW/Hz to –60 dBW/Hz, and if there are horizon obstruction losses. The receiver in the radiolocation system can either be fixed or mobile. With respect to RLS ground-based systems into FSS space station receiving antennas, one study shows that an antenna discrimination of up to 60 dB may be required. Concerning the FSS (space-to-Earth), pfd limits would be required to protect existing RLS systems operating in this band.

15 Frequency band 16.6-17.0 GHz The allocations of this band in RR Article 5 are shown below.

TABLE 15-1 Excerpts from RR Article 5 on allocation to services in 16.6-17.0 GHz

Allocation to services Region 1 Region 2 Region 3 16.6-17.1 RADIOLOCATION Space research (deep space) (Earth-to-space) 5.512 5.513

402 Rep. ITU-R S.2365-0

15.1 Review of Recommendations/Reports A list of relevant Recommendations and Reports that may be useful for sharing studies is in Table 15-2.

TABLE 15-2 Summary of relevant Recommendations/Reports that may be useful for sharing studies in the band 16.6-17 GHz

It may also be useful to review Report ITU-R M.2170 for the radiolocation service.

15.2 Sharing studies for the band 16.6-17.0 GHz 15.2.1 FSS (E-s) and RLS 15.2.1.1 Additional Studies See § 13.2.1.

15.2.2 FSS (E-s) and FS No sharing studies were submitted to the ITU-R for FSS (E-s) satellite systems and fixed service in the band 16.6-17.0 GHz.

15.2.3 FSS (E-s) and MS No sharing studies were submitted to the ITU-R for FSS (E-s) satellite systems and mobile service in the band 16.6-17.0 GHz.

15.2.4 FSS (E-s) and SRS No sharing studies were submitted to the ITU-R for FSS (E-s) satellite systems and the space research service in the band 16.6-17.0 GHz.

15.2.5 FSS (s-E) and RLS See § 13.2.5. Rep. ITU-R S.2365-0 403

15.3 Summary of studies for the band 16.6-17 GHz With respect to RLS airborne systems, separation distances of 420 km (not accounting for terrain obstruction) would be needed to ensure protection between the FSS and RLS airborne systems operating in this band. Moreover, if FSS receiving space is not having sufficient antenna discrimination at low elevation angles, these stations may be subject to interference from existing RLS airborne systems in this band. Another study shows that for fixed, ground-based RLS systems (as opposed to airborne RLS systems) the required separation distances may be reduced down to ranges between 5 to 53 km if the FSS earth station PSDs are reduced to values range from –55 dBW/Hz to –60 dBW/Hz, and if there are horizon obstruction losses. The receiver in the radiolocation system can either be fixed or mobile. With respect to RLS ground-based systems into FSS space station receiving antennas, one study shows that an antenna discrimination of up to 60 dB may be required. Concerning the FSS (space-to-Earth), pfd limits would be required to protect existing RLS systems operating in this band.

404 Rep. ITU-R S.2365-0 Annex

TABLE A-1 Representative technical characteristics of the aeronautical mobile service systems in the frequency range 14.5-15.35 GHz (extracted from Annex 6 to Document 5B/761)

System 1 System 1 System 2 System 2 Units Airborne Ground Airborne Ground Transmitter Tuning range GHz 15.15-15.35 14.50-14.83 14.50-14.83 15.15-15.35 Power output dBm 0 to 30 30 to 50 20 30 to 50 Bandwidth 3 dB MHz 0.354 / 3.5 / 10 / 120 0.354 / 3.5 / 10 / 60 / 120 0.354 / 3.5 / 10 / 60 / 120 0.354 / 3.5 / 10 / 120 20 dB MHz 21 / 21..4 / 57.4 / 285 21 / 25 / 60 / 190 / 400 21 / 25 / 60 / 190 / 400 21 / 21..4 / 57.4 / 285 60 dB MHz 108 / 181 / 219 / 630 100 / 110 / 120 / 240 /480 100 / 110 / 120 / 240 /480 108 / 181 / 219 / 630 Harmonic attenuation dB 65 60 60 65 Spurious attenuation dB 80 52 52 80 Modulation OQPSK OQPSK OQPSK OQPSK Receiver Tuning range GHz 14.50-14.83 15.15-15.35 15.15-15.35 14.50-14.83 RF Selectivity 3 dB MHz 520 440 440 520 20 dB MHz 580 587 587 580 60 dB MHz 720 700 700 720 IF Selectivity 3 dB MHz 36 / 140 27 / 150 27 / 150 36 / 140 20 dB MHz 67 / 400 46 / 210 46 / 210 67 / 400 60 dB MHz 173 / 850 113 / 600 113 / 600 173 / 850 NF dB 4 5 5 4 Sensitivity dBm –75 to –80 –105 to –110 –105 to –110 –75 to –80 Image rejection dB 80 100 100 80 Spurious rejection dB 60 50 50 60

Rep. ITU-R S.2365-0 405 TABLE A-1 (continued)

System 1 System 1 System 2 System 2 Units Airborne Ground Airborne Ground Antenna Antenna gain dBi 24 40 27 7.2 44 3 1st Sidelobe dBi 5.5 @ 21° 20 @ 2.5° 9.7 @ 12° N/A 1 21 @ 2.3° N/A 1 Polarization RHCP 3 RHCP 3 & LHCP 4 RHCP 3 & LHCP 4 Not Available RHCP Vertical Antenna RF Lens Parabolic reflector Parabolic reflector Biconical dipole Parabolic reflector Dipole pattern/Type Horizontal BW degrees 12 1.5 8 360 1.7 360 Vertical BW degrees 12 1.5 8 16 1.7 42 Recommendation Recommendation Recommendation Recommendation ITU-R M.1851 5 ITU-R M.1851 5 ITU-R M.1851 5 ITU-R M.1851 5 Antenna Model Omni Directional Omni Directional (Uniform (Cosine (Uniform (Cosine Distribution) Distribution) Distribution) Distribution) Notes: (1) In the frequency band 14.5–14.8 GHz, RR Articles 21 (§§ 21.2, 21.3 and 21.5) apply. (2) N/A – Not applicable. (3) RHCP – Right Hand Circularly Polarized. (4) LHCP – Left Hand Circularly polarized. (5) Recommendation ITU-R M.1851 provides several patterns based on the field distribution across the aperture of the antenna. The suggested distribution for modelling the antennas is shown in the parenthetical text based on guidance in Recommendation ITU-R M.1851.

406 Rep. ITU-R S.2365-0 TABLE A-1 (continued)

System 3 System 3 System 4 System 4 Parameter Units Airborne Ground Airborne Ground Transmitter Tuning range GHz 14.50-15.35 14.83-15.35 14.50-14.83 15.15-15.35 Power output dBm 0 to 30 40 40 50 Bandwidth 3 dB MHz 3.4 / 10.3 / 20.6 / 27.8 / 0.354 / 3.5 / 40 34 9.15 42.9 20 dB MHz 21 / 21..4 / 85 44 7 / 18.8 / 37.6 / 78.5 / 112 36.6 60 dB MHz 108 / 181 / 190 45.6 20 / 67.2 / 134 / 281 / 320 76.6 Harmonic attenuation dB 65 65 65 65 Spurious attenuation dB 80 80 80 80 Modulation OQPSK 16 APSK QPSK, OQPSK OQPSK Receiver Tuning range GHz 14.83-15.35 14.50-15.35 15.15-15.35 14.50-14.83 RF Selectivity 3 dB MHz 520 440 307 340 20 dB MHz 580 587 325 400 40 dB Not Available Not Available 399 540 60 dB MHz 720 700 Not Available Not Available IF Selectivity 3 dB MHz 50 50 130 36.5 20 dB MHz 85 70 400 59.1 60 dB MHz 135 120 1 200 103.7 NF dB 5 4 4.5 6 Sensitivity dBm –99 –105 to –110 –106 –92 Image rejection (dB) 100 100 80 85 Spurious rejection (dB) 50 50 60 85

Rep. ITU-R S.2365-0 407 TABLE A-1 (continued)

System 3 System 3 System 4 System 4 Parameter Units Airborne Ground Airborne Ground Antenna Antenna gain dBi 24 45 3.7 19.5 3 40 1st Sidelobe dBi 3.5 @ 20° (Azimuth) 5.5 @ 21° 20 N/A1 N/A1 22 4.0 @ 23° (Elevation) Polarization RHCP 3 RHCP 3 RHCP 3 RHCP 3 RHCP 3 RHCP 3 Antenna Biconical Parabolic RF Lens Parabolic reflector Biconical Dipole RF Lens pattern/Type Dipole Reflector Horizontal BW Degrees 12 1.11 360 12 360 3.8 Vertical BW Degrees 12 1.11 40 12 42 3.8 Antenna Model Recommendation Recommendation ITU-R M.1851 5 ITU-R M.1851 5 TBD TBD TBD TBD (Uniform (Cosine Distribution) Distribution) Notes: (1) In the frequency band 14.5–14.8 GHz, RR Articles 21 (§§ 21.2, 21.3 and 21.5) apply. (2) N/A – Not applicable. (3) RHCP – Right Hand Circularly Polarized (4) LHCP – Left Hand Circularly polarized (5) Recommendation ITU-R M.1851 provides several patterns based on the field distribution across the aperture of the antenna. The suggested distribution for modelling the antennas is shown in the parenthetical text based on guidance in Recommendation ITU-R M.1851.

408 Rep. ITU-R S.2365-0 TABLE A-1 (continued)

System 5 System 5 System 6 Parameter Units Airborne Ground Airborne / Ground / Shipboard terminals Transmitter Tuning range GHz 14.5-15.35 N/A 14.5-15.35 Power output dBm 10 to 50 N/A 20 to 43 Bandwidth 3 dB MHz 0.8 / 8.6 / 11.6 / 40.6 / 43.6 N/A 0.8 / 100 20 dB MHz 1.2 / 12.1 / 16.1 / 57 / 61.2 N/A Not Available 40 dB MHz 2.8 / 15.6 / 20.5 / 73.2 / 80 N/A Not Available 60 dB MHz 9.8 / 24.4 / 32.6 / 114 / 122 N/A 9.8 / 160 Harmonic attenuation dB 65 N/A 60 Spurious attenuation dB 70 N/A 60 Modulation QPSK/8PSK N/A PSK/QPSK/8PSK Receiver Tuning range GHz N/A 14.5-15.35 14.5-15.35 RF Selectivity 3 dB MHz N/A 800 120 20 dB MHz N/A Not Available Not Available 60 dB MHz N/A 1 900 Not Available IF Selectivity 3 dB MHz N/A 0.85 / 8.8 / 11.7 / 40.7 / 43.7 0.85 / 120 20 dB MHz N/A 1.3 / 18 / 23 / 90 / 90 Not Available 60 dB MHz N/A 3;2 / 61; 81; 320 / 320 Not Available NF dB N/A 3.5 3.5 Sensitivity dBm N/A Up to –111 –110 Image rejection (dB) N/A 60 60 Spurious rejection (dB) N/A 60 65

Rep. ITU-R S.2365-0 409 TABLE A-1 (continued)

System 5 System 5 System 6 Parameter Units Airborne Ground Airborne / Ground / Shipboard terminals Antenna Antenna gain dBi –3 to 27.5 42.5 0 to 12 1st Sidelobe dBi Rejection@20dBc Rejection@20dBc Rejection @ 20dBc Polarization RHCP 3 RHCP 3 Vertical/RHCP 3 Antenna pattern/Type Dipole/Parabolic reflector Parabolic reflector Dipole/Phase array Horizontal BW Degrees 360 to 7 1 360 to 45 Vertical BW Degrees 90 to 7 1 90 to 45 Antenna Model TBD TBD TBD Notes: (1) In the frequency band 14.5–14.8 GHz, RR Articles 21 (§§ 21.2, 21.3 and 21.5) apply. (2) N/A – Not applicable. (3) RHCP – Right Hand Circularly polarized. (4) LHCP – Left Hand Circularly polarized. (5) Recommendation ITU-R M.1851 provides several patterns based on the field distribution across the aperture of the antenna. The suggested distribution for modelling the antennas is shown in the parenthetical text based on guidance in Recommendation ITU-R M.1851.

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