ACP-WGW24/IP- International Civil Aviation Organization 01 14 March 2011 WORKING PAPER

AERONAUTICAL COMMUNICATIONS PANEL (ACP)

24th MEETING OF WORKING GROUP F

Paris, 21 March – 25 March 2011

Agenda Item 5: Interference from non-aeronautical sources

Ancillary Terrestrial Emitters / GNSS Spectrum concerns

(Presented by Claude Pichavant)

SUMMARY This paper present the concerns posed by new Ancillary Terrestrial Emitters to navigation based on GPS and in the future on GNSS, according to waiver requested to FCC in US. ACTION To note the information provided above and, where appropriate, use the information in preparing contributions or formulation of guidelines as to how aviation should response to such potential interference threats.

1. INTRODUCTION

1.1 General Information about LightSquared

In the frame of Mobile Satellite Service to be used for Terrestrial Broad Band, LightSquared company plans to install up to 40,000 base stations, with high power transmitters adjacent to RNSS Band (1559 MHz to 1610 MHz).

In response to his request to FCC and despite several comments and concerns raised by the GPS community, in particular the GPS aviation community, LightSquared has been granted a conditional waiver and was required by the FCC to help organize and fully participate in a working group that includes the GPS community and federal agencies to study the potential for overload to GPS devices and

(6 pages) 0f89348baefae7bef0f06f6709c87140.doc 2 ACP-WGF24/IP-01 to identify any measures necessary to prevent harmful interference to GPS.

Several reports are due including an initial report to the FCC and NTIA by February 25, 2011 that includes a work plan for the analysis and tests and a final report due at the FCC no later than June 15, 2011.

1.2 Background

According to the FCC waiver published on January 26, 2011, refer to enclosed Attachment 1 (FCC DA 11-133):

Quote “GPS-Related Interference Concerns

39. Several commenters raise concerns about potential interference to GPS receivers and other devices that may result from operation of LightSquared’s base stations, while LightSquared asserts that it continues to meet its obligations with regard to addressing interference concerns. NTIA also expresses concern that LightSquared’s services could adversely impact GPS and other GNSS receivers, and asks that the Commission address these inference issues before interference occurs. We emphasize that any potential interference to GPS is a significant concern, and note that the Spectrum Task Force at the Commission recently established an internal technical working group dedicated to examining this issue.

40. The U.S. GPS Industry Council proposes that NTIA, working with industry and government technical experts, examine the potential for interference within a reasonable time frame, not to exceed 90 days.In its letter, NTIA states that, if the Commission grants LightSquared’s request, the Commission should establish a process that will ensure the interference issues are resolved prior to LightSquared’s offering service that could cause interference, and that will motivate all parties to move expeditiously and in good faith to resolve the issues.NTIA further states that it stands ready to work with the Commission, LightSquared, and affected parties and concerned Federal agencies to address these interference concerns. More recently, LightSquared states that it takes the concerns raised by the GPS community about possible overload of GPS devices by LightSquared’s base stations very seriously, and that it is appropriate for interested parties to devote resources to a solution as soon as possible. LightSquared professes confidence that the issues can be resolved without delaying deployment of its network. At the same time, in order to address the concerns raised, LightSquared states that it would accept, as a condition of the grant of its request, the creation of a process to address interference concerns regarding GPS and, further, that this process must be completed to the Commission’s satisfaction before LightSquared commences offering commercial service, pursuant to the approval of its request, on its LBand MSS frequencies. Further, LightSquared commits to working diligently and cooperatively with the Commission, NTIA and the Federal agencies, and the GPS community to help resolve the interference issues through a rigorous process that can address these issues in a comprehensive manner. 41. We agree on the need to address the potential interference concerns regarding GPS as LightSquared moves forward with plans to deploy and commence commercial operations on its network. Further, we believe that establishing a working group that brings LightSquared and the GPS community together to address these interference issues expeditiously would serve the public interest. We envision a working group in which cooperative and candid discussions can ensue, and where information, including proprietary information, can be shared among the participants with appropriate measures in place to protect the confidentiality of that information. Commission staff will work with NTIA, LightSquared, and the GPS community, including appropriate Federal agencies, to establish a working group to fully study the potential for overload interference to GPS devices and to identify any measures necessary to prevent harmful interference to GPS. As a condition of granting this waiver, the 3 ACP-WGF24/IP-01 process described below addressing the interference concerns regarding GPS must be completed to the Commission’s satisfaction before LightSquared commences offering commercial service pursuant to this waiver on its L-band MSS frequencies.

42. As an additional condition of granting this waiver, we require LightSquared to help organize and fully participate in the working group described above. The working group shall focus on analyzing a variety of types of GPS devices for their susceptibility to overload interference from LightSquared’s terrestrial network of base stations, identifying near-term technical and operational measures that can be implemented to reduce the risk of overload interference to GPS devices, and providing recommendations on steps that can be taken going forward to permit broadband wireless services to be provided in the LBand MSS frequencies and coexist with GPS devices. Because the GPS interference concerns stem fromLightSquared’s transmissions in its authorized spectrum rather than transmissions in the GPS band, the Commission expects full participation by the GPS industry in the working group and expects the GPS industry to work expeditiously and in good faith with LightSquared to ameliorate the interference concerns.

43. Further, we require that LightSquared submit an initial report to the FCC and NTIA by February 25, 2011, that includes a work plan outlining key milestones for the overall analyses. In addition, LightSquared must submit progress reports on the 15th day of each succeeding month or first business day thereafter. The first of these reports must at a minimum include base station transmitter characteristics, categories of GPS devices and their representative performance characteristics, and test plans and procedures. LightSquared is further required to submit a final report no later than June 15, 2011, that includes the working group’s analyses of the potential for overload interference to GPS devices from LightSquared’s terrestrial network of base stations, technical and operational steps to avoid such interference, and specific recommendations going forward to mitigate potential interference to GPS devices. The Bureau reserves the right to adjust the reporting dates and requirements in consultation with NTIA. The process will be complete once the Commission, after consultation with NTIA, concludes that the harmful interference concerns have been resolved and sends a letter to LightSquared stating that the process is complete.”Unquote

2. DISCUSSION

This decision led to Aviation GPS Receiver Manufacturers, Airframers and Airlines concerns.

Since its introduction in Aviation in the mid 90s, GPS has never stopped spreading around the world, increasing aircraft capacity to navigate on more direct routes, independently of the ground navaids network and enabling precision approach and landing. The International Civil Aviation Organization has recommended the wide use of GNSS for Navigation and its use for Surveillance is also promoted.

Currently, a vast majority of aircraft are equipped with GPS receivers as a primary means or a supplemental means of navigation, in compliance with airworthiness requirements as set by FAA TSO C129 A or TSO C190, for En Route down to Non precision Approaches and FAA TSO C145/C146 and TSO C161/C162 using GBAS or SBAS to achieve Category I minima..

This large GPS equippage, continuously evolves positively, in line with ICAO ANC resolutions to encourage and develop the use of GNSS technology for the benefits of Safety in aviation, in particular to mitigate the risk of Controlled Flight Into Terrain. 4 ACP-WGF24/IP-01

GPS utilization in aviation has had a great impact on:  Safety providing with geometrical vertical guidance, and higher integrity monitoring,  Traffic to satisfy the increasing air transport demand by providing more precise routes and enable closer separation,  Environment providing more direct routes and enabling fuel burn reduction and in the future will help reduce ground infrastructure through the reduction of ground navaids.

However, the emergence of such ancillary terrestrial emitters, in such close band to RNSS, raise a threat with regard to many aspects.

Despite, the emission is not directly in the GPS protected band, the current interference mask set by GPS Industry Standards such as the ones developed by RTCA, Inc are unlikely to protect receivers compliant with these standards. Initial analysis established by key experts and Receiver Manufacturers shows a real threat to GPS receiver putting at risk availability and continuity of the operations, all the more so since several aircraft would be affected a the same time within a terminal area or during final approach.

Aviation Standards are the Industrial Standards which set the most stringent requirements to the GPS receivers as they include Integrity Requirements to ensure Safety of the Operation and sustainment of GPS performance for Navigation and Surveillance applications under Aeronautical environment such as Interference, High Intensity Radiated Filed and Lightning. This leads to a very heavy process qualification of receivers, at receiver manufacturers and airframers levels in line with Airworthiness Requirements.

Despite the problematic is presented as an internal US issue, Aviation is not only limited to US National Air Space as international carriers embedding GPS receivers compliant with ICAO requirements are flying inbound and outbound of US airspace. GPS receivers installed on these carriers are compliant with ICAO and Industry Standards requirements assuming an acceptable and internationally validated worldwide environment in terms of interference. As a consequence, this local issue put a threat on international fleet of aircraft equipped with GPS receivers.

Besides, future ATM concepts as drawn up by European SESAR (Single European Sky ATM Research Programme) and US NextGEN, identify performance based operations, that cover all phases of flight, gate to gate, including the Cruise phase, Precision Approach in all weather conditions as well as surface navigation. These functions will only be possible by the extension of GPS utilization, as long as it is still properly protected, while facing many challenges and opportunities.

First of all, Aviation Operations are more and more demanding as they require enhanced accuracy, integrity and continuity while maximizing availability, in order to enable more stringent operations in terms of aircraft separations and minima. This has been made possible thanks to data accumulation and confidence gained in GPS over the past 30 years, as well as the more accurate knowledge of their real performance and failure modes. But, as we become increasingly reliant on GNSS technology, we must take account of the fact that the GPS signal power is weak and must be acquired and tracked in the middle of other sources of radiation in-band or out-of-band such as VHF, SATCOM, DME, mobile phones, TV, UWB devices, Terrestrial Emitters and other GNSSs signals (i.e. intra and inter-system interferences). This leads to interference masks and installation rules for receivers, set by Industrial standards, as well as band protections for aeronautics. It appears that these threats, sometimes very harmful to satellite navigation, are highly taken into consideration by the aviation community. The validation of the GNSS 5 ACP-WGF24/IP-01 technology for Aviation, has never been so extensive for the benefit of safety, but at the same time, this validation under new threats such as the one presented above, risks delaying the benefits for Aviation stakeholders and even slow it down.

This kind of threats to GNSS, is affecting the performance of the users as they can deny the service, affecting availability and/or continuity of the operations based on GNSS, all the more so since all users would be affected at the same time increasing the workload of Aircrews and Air Traffic Controllers. This could be the case for broadband interference over a large area.

At the same time, a promising opportunity is given by the emergence of new, stronger and diverse signals from international GNSS Programs such as Galileo, the European Satellite Navigation System, Glonass from Russian Federation and Compass from China, but also GPS modernization, planned to be operational around 2020 timeframe. Besides, augmentations systems are providing enhanced performance and sometimes barriers against these threats like Satellite Based Augmentation Systems (SBAS) including WAAS covering the US Air Space, EGNOS covering European Civil Aviation Conference Airspace, MSAS covering the Japanese Airspace, GAGAN covering the Indian Airspace and SDCM covering the Russian Airspace. Ground Based Augmentation System (GBAS) has also some features against these threats while providing Category III capability in the near term. According to the local apparent nature of the issue, the future signals in L-Band that have secured the frequency filling as set by ITU, are not formally investigated by LightSquared and FCC putting at risk the necessary interoperability and compatibility needed for GNSS signals used in Aviation. With this respect, nothing forces LighSquared to alert ICAO and potentially requests an investigation and a waiver on this matter.

Finally, Terrestrial Broad Band Base station transmitters incorporate high selectivity filters to reduce out of band emissions in GPS band. Due to the closeness of these emissions without these filters, it is key that safety assurance and reliability studies be performed to anticipate the potential failures of these filters, assess the effects on the GNSS signals and when deemed necessary set appropriate levels of design assurance to prevent from being under these kind of failures during operation.

RTCA SC-159 GPS WG-6 “Interference” has held a dedicated session with Industry and FAA, including Lightsquared early February 2011. Industry, with RTCA and FAA, on a voluntary basis, are supposed to help establish a test plan to formally determine whether these emitters are harmful to aviation GPS receivers and identify potential mitigation techniques, when deemed necessary. It is important to note that there is no near term plan to impose a modification on fielded receivers, even more considering the high number of fielded equipment and the impact it would have on Air Traffic Management. Final assessment report to FCC is planned mid June. It has been suggested that aviation community express its concerns and direct it to all necessary levels towards FCC and Us Federal agencies involved in this assessment. This paper is providing information to ICAO WGF to provide appropriate awareness on this issue.

3. ACTION BY THE MEETING

3.1 The ACP WGF is invited to note the information provided above and, where appropriate, use the information in preparing contributions or formulation of guidelines as to how aviation should response to such potential interference threats. 6 ACP-WGF24/IP-01

Attachment 1

FCC Order DA 11-133

lightsquared-order-fc c-10991.pdf