ACP-WGF18/WP07 International Civil Aviation Organization 12-22 May 2008

WORKING PAPER

AERONAUTICAL COMMUNICATIONS PANEL (ACP)

EIGHTEENTH MEETING OF WORKING GROUP F

Montreal, Canada 12-22 May 2008

Agenda Item 5 Development of material for ITU-R meetings

Studies Requested by Res. 222 (Rev. WRC-07) for WRC-11 Agenda Item 1.7 （Methodology for the Calculation of AMS(R)S Spectrum Requirements）

(Presented by K. INOGUCHI, Japan) (Prepared by Y. SUZUKI)

SUMMARY

This Working Paper provides information of the work for the ITU-R WP4C relating to WRC-11 Agenda Item 1.7 to WG-F participants and requests active participation and contribution to the work of WP 4C asking possible comment on this document which is being prepared to the next WP 4C meeting by Japan.

ACTION

WG-F members are encouraged to consider this working paper and actively participate and contribute the work for the study in the ITU-R WP 4C relating to WRC-11 Agenda Item 1.7, AMS(R)S spectrum issues

1. Introduction WRC-07 adopted WRC-11 Agenda Item 1.7 to consider methods to ensure long-term and stable spectrum availability for AMS(R)S inviting ITU-R under Resolution 222 (Rev. WRC-07) to study on this subject with ICAO and other organizations concerned.

ITU-R WP 4C, responsible group for this Agenda Item, adopted a work plan for this study at the first meeting in April, and decided to study methodology and conditions to calculate current and future AMS(R)S spectrum requirement at the second meeting to be held in October this year.

This Working Paper provides information of the work for the ITU-R Working Party 4C (WP 4C) - 2 - relating to WRC-11 Agenda Item 1.7 to WG-F participants and requests active participation and contribution to the work of WP 4C asking possible comment on this document which is being prepared to the next WP 4C meeting by Japan.

2. Background 2.1 AMS(R)S Spectrum Problems The International Civil Aviation Organization (ICAO) standardized the use of the 1.6/1.5 GHz band in 1995 as an essential element of aeronautical mobile satellite systems to enable safety communications, and spectrum demand will increase for the next generation of aeronautical satellite communication systems. At WRC-97, the sub-bands 1 545-1 555 MHz (space-to-Earth) and 1 646.5-1 656.5 MHz (Earth- to-space), which had been exclusively allocated to the aeronautical mobile-satellite (route) service (AMS(R)S) for communications relating to safety and regularity of flights (messages with priority 1 to 6 as per Article 44 of the Radio Regulations), were allocated to generic mobile- satellite service (MSS). WRC-2000 considered this subject again and adopted Resolution 222 (WRC-2000) to resolve that Administrations shall ensure spectrum for safety communications and to invite ITU-R to complete studies to determine the feasibility and practicality of prioritization and real-time pre- emptive access between different networks. ITU-R carried out the studies on this subject, and adopted Report ITU-R M. 2073 concluding that "prioritization and intersystem real-time pre- emption" is not practical and, without significant advance in technology, is unlikely to be feasible for technical, operational and economical reasons As demand for AMS(R)S communication to support the ICAO satellite applications for communication, navigation, surveillance and air traffic management (CNS/ATM) is increasing, the ICAO sets its position for Agenda Item 7.2 of WRC-07 to support WRC-11 Agenda Item for methods to ensure long-term and stable spectrum availability for AMS(R)S, and to provide appropriate regulatory and operational provisions.

2.2 WRC-11 Agenda Item 1.7 WRC-07 discussed this issue based on proposals from APT, Arab Group, CEPT and Canada/USA, modified Resolution 222 and adopted Agenda item 1.7 for WRC-11 "to consider the results of ITU-R studies in accordance with Resolution 222 (Rev.WRC-07) in order to ensure long- term spectrum availability and access to spectrum necessary to meet requirements for the aeronautical mobile-satellite (R) service, and to take appropriate action on this subject, while retaining unchanged the generic allocation to the mobile-satellite service in the bands 1 525-1 559 MHz and 1 626.5-1 660.5 MHz;". Resolution 222 modified at the WRC-07 "invites ITU-R to conduct, in time for consideration by WRC-11, the appropriate technical, operational and regulatory studies to ensure long-term spectrum availability for the aeronautical mobile-satellite (R) service (AMS(R)S) including: (i) to study, as a matter of urgency, the existing and future spectrum requirements of the aeronautical mobile-satellite (R) service; (ii) to assess whether the long-term requirements of the AMS(R)S can be met within the existing allocations with respect to No. 5.357A while retaining unchanged the generic allocation for the mobile- satellite service in the bands 1 525-1 559 MHz and 1 626.5-1 660.5 MHz, and without placing undue constraints on the existing systems operating in accordance with the Radio Regulations; (iii) to complete studies to determine the feasibility and practicality of technical or regulatory means, other than the coordination process referred to in resolves 1 or the means considered in Report ITU-R M.2073, in order to ensure adequate access to spectrum to accommodate the AMS(R)S requirements as - 3 - referenced in resolves 3 above, while taking into account the latest technical advances in order to maximize spectral efficiency; (iv) if the assessment identified in invites ITU-R (i) and (ii) indicates that these requirements cannot be met, to study existing MSS allocations or possible new allocations only for satisfying the requirements of the aeronautical mobile satellite (R) service for communications with priority categories 1 to 6 of Article 44, for global and seamless operation of civil aviation taking into account the need to avoid undue constraints on existing systems and other services, invites WRC-11 to consider the results of the above ITU-R studies and to take appropriate action on this subject, while retaining unchanged the generic allocation to the mobile-satellite service in the bands 1 525-1 559 MHz and 1 626.5-1 660.5 MHz, invites the International Civil Aviation Organization (ICAO), the International Maritime Organization (IMO), the International Air Transport Association (IATA), administrations and other organizations concerned to participate in the studies identified in invites ITU-R above."

2.3 WP 4C Work Plan ITU-R WP 4C, responsible group to WRC-11 Agenda Item 1.7, adopted the Work Plan responding to Res. 222 by proposed framework for the 2008-2011 study period. During this process, ICAO, IMO, IATA and concerned organizations are invited to participate in the studies. Details of the Work Plan are indicated in the Annex 13 to the WP 4C Chairman's Report of the first meeting (Doc. 4C/66) . It shows that, relating to invites (i) of the Resolution 222 (Rev. WRC-07), it is requested to establish a globally accepted methodology to determine existing and future spectrum requirements for AMS(R)S and to identify all required parameters at the 2nd meeting of WP 4C in October 2008 like: o type of aeronautical communication o size of the coverage area and the service area o frequency reuse o flight phase (high altitude, oceanic, etc) o type of signal (data, voice) o availability of AMS(R)S communications o BER, delay time, data rate, utilization rate o the appropriate transmission system o air traffic scenario(s) and others.

3. Discussions Studies of required spectrum for the AMS(R)S were carried out in ICAO, IATA for a long time, and some contribution were submitted to past ITU-R meetings as shown in Annex 1. However, these results were not well refracted in succeeding studies of the ITU-R as agreed future spectrum requirement for the AMS(R)S because methodology and conditions were different. As the WRC -11 Agenda Item for this subject is adopted and results of the estimation of the AMS(R)S spectrum requirements are considered to be basic information for the study in WP 4C, it is required to make methodology and its conditions clear and agree them by the WP as common understandings for the determination of current and future spectrum requirements. Although methodology for the calculation of required spectrum for MSS portion of IMT-2000 is - 4 - determined by ITU-R Recommendation M.1391, but it seems to be difficult to apply to the calculation of AMS(R)S since conditions to be considered are different, and therefore special methodology would be necessary.

MTSAT operator has been calculationg the required spectrum for AMS(R)S each year for the purpose of Regions 1 & 3 1.6/1.5 GHz GSO-MSS frequency coordination based on the concept of the methodology for the calculation as provided to the WG-F/7 meeting held in 2001(WP62). This method was based on the estimated value of peak instantaneous aircraft count (PIAC) from the world airlines time table, and is to obtain required spectrum for the AMS(R)S communications taking into account of estimated values of communication traffic. The methodology for the calculation to be used in the study of WP 4C for WRC-11 will be globally accepted and use for longer term estimation of spectrum requirements of the AMS(R)S, but basic concept should be same as used for the case of the MTSAT above. Japan is preparing to submit draft working document as shown in Annex 2 based on the methodology as above and taking into account of ITU-R Rec. M. 1391 to the next WP 4C meeting for their consideration. WG-F participants are asked to consider this working paper and to provide any comments on this paper to authors for improvement.

4. Proposal WG-F members are encouraged to consider this working paper and actively participate and contribute the work for the study in the ITU-R WP 4C relating to WRC-11 Agenda Item 1.7, AMS(R)S spectrum issues, including the followings. (1) Provide any comments on this working paper to the author (e-mail: [email protected]), especially on the Annex 2. (2) Actively participate in and contribute to the work of the ITU-R WP 4C on this subject. (3) Participate to the preparatory activities in respective states for the WRC-11 Agenda Item 1.7 and make their Administration understand ICAO position for this subject.

Annex 1 Information relating to AMS(R)S Spectrum Requirements Annex 2 Preliminary Draft: Proposed Methodology for the Calculation of AMS(R)S Spectrum Requirements - 5 -

Annex 1 Information relating to AMS(R)S Spectrum Requirements

Year Doc. No. Title Origin Summary Appendix 1 to Estimation of future Spectrum Requirements Year 2010 1990 IWP8/15 IWP 8/15-1 for the Aeronautical Mobile Satellite Service Required BW: 17.5 MHz AMS(R)S Communications Traffic Predictions and Spectrum Requirements for Year 2010 1998 8D/114 ICAO the Bands 1545-1555 MHz and 1646.5 - Required BW: 11 MHz 1655.5 MHz to the Year 2010 Long Term Spectrum Requirements of Year 2020 1998 8D/133 ESA AMS(R)S Required BW: 6 MHz Year 2010 1999 8D/227 MSS Spectrum Estimation for AMS(R)S ICAO-IATA Required BW: 10.8 MHz Long Term Spectrum Requirements of Year 2025 1999 8D/275 UAE AMS(R)S Required BW: 1.1 MHz - 6 -

Annex 2

Preliminary Draft Proposed Methodology for the Calculation of AMS(R)S Spectrum Requirements

1. Introduction This document provides an example of methods of calculation of AMS(R)S spectrum requirements as basic information for the study responding to the request of the Resolution 222 for the study on WRC-11 Agenda Item 1.7.

2. Type of AMS(R)S communications and FIR organization There are two kinds of AMS(R)S communications, data and voice. It is necessary to handle them separately for the calculation because their natures are different. Data communication is mainly used for routine communications such as air traffic control and aeronautical operational control. There are two different natures of channel requirements, such as indispensable channels to be assigned to each beam for communication control, channels to be assigned to each airspace for air traffic control and flight information service, and other AOC communication channels proportional to number of operating aircraft. As for the voice communication, it is currently used for transmission of non-routine information that data communication will have some difficulties. Accordingly it may be necessary to reserve at least one channel per designated operational coverage area (Sector) in the flight information region (FIR) for the need of unexpected communication such as in the case of sudden meteorological deterioration, situations causing a risk to the aircraft and revision of flight plan. For the AOC communications, their traffic will depend on the number of operating aircraft as usual, except in non-routine situation.

3. Methods of calculating required spectrum for AMS(R)S As characteristics of frequency demands for the AMS(R)S are different from that of general MSS as indicated by the Recommendation ITU-R M.1391, different methods of calculating required spectrum need to be developed. Proposed method is based on the estimation of peak instantaneous aircraft count (PIAC) from the world airlines time table, and is to obtain required spectrum for the AMS(R)S communications taking into account of estimated values of communication traffic. The methods and steps of the calculation are summarized in Figure 1. It is necessary to provide appropriate conditions prior to estimate required spectrum for AMS(R)S including the followings. - Applicable airspace: Global beam, Spot beams or Zones,. - Season or time slot: Both in the busiest hour and off peak hour, etc. - Category of aircraft operation: Scheduled, Non-scheduled, etc. - Type of signals: Data or Voice - Types of avionics - 7 - 3.1 Estimation of Peak Instantaneous Aircraft Count (PIAC): Step 1 a) Reference year's PIAC It is considered that communication traffic is nearly proportional to the number of operating aircraft. Therefore, Peak Instantaneous Aircraft Count (PIAC) for the year of interest (Target year's PIAC) in the specified airspace, beam or zone (i), may be estimated as a base of calculating required spectrum. Generally, the number of operating aircraft widely varies and needs to be investigated in hourly, daily and seasonally basis. Peak value in the busiest hour in the year and specified airspace (beam or zone) shall be obtained, or estimated by taking into account of growth rate for the year. The PIAC for the scheduled flight in some specific (reference) year (Ar) may be obtained by investigating airlines timetable database of the year, such as OAG (Official Airlines Guide). An example of daily PIAC variation in Asia and the Pacific area is shown in figure 2.

b) PIAC using satellite communications The Target year’s PIAC using satellite communications in the specified airspace may be obtained as the product of target year's PIAC of all aircrafts (At) and the ratio of aircraft using satellite communication (Rs). The PIAC for scheduled flights of target year, which is n-years later from the reference year, may be obtained by reference year’s PIAC applying growth factor (Rg) obtained by statistical data or yearly growth rate based on the economical growth. The PIAC of non- scheduled flights may be estimated by applying the ratio of scheduled and non-scheduled flights and the PIAC of the general aviation (GA) may be estimated by applying the ratio of scheduled and GA flights based on the statistical data of GA flight hours. These two factors may be considered together as "Scheduled flight and GA & Non schedule flight Factor (Rn)". Target year's PIAC is then obtained by summing up the above PIAC's, for scheduled flight, for non-scheduled flight and for general aviation.

3.2 Estimation of number of channel : Step 2 a) AMS(R)S Normalized (Standardized) Channel Although various types of modulation and carrier bandwidth are used in the satellite communication system, normalized (standardized) carrier bandwidth may be used for simplification. For example, for classic aeronautical satellite communication system as defined by ICAO SARPs, 600 bit/s channel may be used as normalized channel for the data communications based on the number of information bit with error control bits and other necessary overheads, and 21,000 bit/s channel may be used for the voice communications.

b) Estimation of number of normalized channels In the case of data communications, required number of normalized channel (Nd) may be estimated by considering peak data traffic (Td) based on the satcom equipped PIAC (As) and estimated data per aircraft in one hour (Kd), capacity per data channel (C) and allowable delay time (D). In the case of voice communications, required number of normalized channel (Nv) may be estimated by considering peak voice traffic (Tv) based on satcom PIAC (As) and estimated voice traffic per aircraft (Kv), and allowable call loss (L). - 8 - 3.3 Calculation of Required Spectrum : Step 3 Required spectrum can be calculated by summing up the products of required number of channel obtained above and its bandwidth taking into account of channel utilization factor and frequency reuse factor as follows.

Required Spectrum (B) = (Bs x Ns,i x Ui x Fi) s,i Where;

Bs: Required Bandwidth Per Channel

Ns,i: Required Number of Channel

Ui: Channel Utilization Factor

Fi: Frequency Reuse factor s: Type of signal i: Beam or Zone - 9 -

STEP 1 Airborne Count Airline Timetable (OAG) Beam/Zone: i

Peak Instantaneous Aircraft Count Scheduled Flight for Reference Year Ari (count)

Target Year : Y Growth rate : Rg(%) GA&Non Schedule ratio: Rn(Times) Satcom Equipped ratio: Rs(%)

Peak Instantaneous Aircraft Count Satcom Equipped Aircraft Asi (count)

STEP 2 Number of Channel Data Voice

Unit Data: Kd (kbit/s) Unit Traffic: Kv (Earlang) Peak Data Traffic Peak Voice Traffic Tdi (bit/Hr) Tvi (Earlang)

Capacity per Carrier: C (kbit/s) Call Loss: L (%) Data Delay: D (s)

Number of Data Number of Voice Channel Channel Ndi (ch) Nvi (ch) STEP 3 Bandwidth Channel Bandwidth: Bd (kHz) Channel Bandwidth: Bv (kHz)

Total Bandwidth for Specific Beam/Zone Bi (kHz)

Other Beams/Zones i Channel Utilization Factor Ui (%) Frequency Reuse Factor Fi (times)

Required Bandwidth B (kHz)

Figure 1 Flow of Calculation of AMS(R)S Spectrum Requirement - 10 -

最混雑日(12月22日)における時間帯毎の機数推移 － MTSATビーム別： 定期便 Hourly Aircraft Count in MTSAT Beams for Busiest Day (22nd Dec. 2006) 3500

3000

2500 All In Cover A1 SpotBeam 2000 A2 SpotBeam A3 SpotBeam t n u o A4 SpotBeam C t f a r c r 1500 i A5 SpotBeam A A6 SpotBeam SpotBeamTTL 1000 GlobalBeam

500

0 00- 01- 02- 03- 04- 05- 06- 07- 08- 09- 10- 11- 12- 13- 14- 15- 16- 17- 18- 19- 20- 21- 22- 23- 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 UTC

Figure 2 Example of PIAC( Asia and Pacific Zone )

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