SATELLITE DATA LINK SYSTEM (SDLS)

1. SATELLITE DATA LINK SYSTEM(SDLS) A DEDICATED MOBILE SATELLITE COMMUNICATION SYSTEM RESPONDING TO THE HIGHLY DEMANDING REQUIREMENTS OF CIVIL AVIATION Claude Loisy European Space Agency (ESA) ICAO/AMCP WG C 2nd meeting

2. Satellite Data Link System ICAO/AMCP WG C 2nd meeting

3. The Air/Ground Communications of Civil Aviation • Two Categories of Communications • Safety related : ATS (Air Traffic Services) AOC (Airline Operational Communications) • Non Safety related :  AAC  and  APC (passenger communication) • Technical Requirements for Safety Related • Specified by ICAO (SARPs) • Mandated by States to Air Transport • Communication Systems Deployed at Present • Terrestrial “VHF” : generally available in continental airspace • Terrestrial “HF” : low capacity, slow response but worldwide coverage • Satellite “AMSS” : costly and deployed on only 2000 aircraft ICAO/AMCP WG C 2nd meeting

4. Meeting the Future Capacity Requirements of Safety Communications • Required Capacity is Steadily Increasing • Air Traffic volume displays an almost constantly expanding trend • Anticipated reduction in aircraft geometrical separations will induce an increase in tactical exchanges and the per aircraft communication traffic • The VHF Aero Band is Nearing Saturation • Frequency Re-use is severely limited by network geometry • Recent Introduction of higher efficiency modulation techniques for voice (8.33 KHz instead of 25 KHz channels) is buying some extra time • Introduction of data services will initially increase spectrum demand • Introduction of a new system is being studied • Satellite is among the options under consideration ICAO/AMCP WG C 2nd meeting

5. ICAO Requirement Summary for theNext Generation Satellite System • Geographical Coverage • Worldwide coverage is needed • Two types of scenario: • LEO or MEO constellation • Interoperable GEO based networks • Continuity of Service Provision • Users expect high continuity based on a stable technical standard • Avionics lifetime should by far exceed that of aircraft (no retrofits) • Services and Associated Performances • Voice and/or Data • Fast response and high availability • Affordable Costs ICAO/AMCP WG C 2nd meeting

6. SDLS Main System Options • Safety Communication Dedicated System • Allows stable and less challenged access to radio frequency spectrum • Avoids the inherent risks of sharing resources with a business venture • Highly simplifies the design and reduces costs • Open Technical Standard • GeosynchronousOrbit (HEIO for the N polar cap) • Capability for Highly DistributedSatellite Access • Aircraft Earth Station Characteristics • Low cost isotropic antenna • Low cost single channel and medium transmit power level ICAO/AMCP WG C 2nd meeting

7. SDLS Main Design Characteristics (1) • Services • Voice service (point to point and “Party Line”) • Data service including broadcast and polled on-board parameter retrieval • Network Architecture • Capability for decentralised satellite access • Satellite Diversity • Dictated by service availability requirements • Equipment Redundancy • For both airborne and ground is part of the design • Communication Resource Management • Fixed and demand assignment, handling of priority levels ICAO/AMCP WG C 2nd meeting

8. SDLS Main Design Characteristics (2) • Multiple Access Scheme • Synchronous CDMA in the fixed to mobile direction • Quasi Synchronous CDMA in the mobile to fixed direction • Fixed Earth Stations • Ku or C-Band depending on satellite feeder links • Only Ku-Band VSATs practically allow highly decentralised access • Aircraft Earth Stations • Low cost solutions meeting avionics standards are readily available • Only the CDMA modems require a specific development • Space Segment • MSS GEO satellites at L-Band have already been deployed worldwide ICAO/AMCP WG C 2nd meeting

9. The SDLS Demonstrator • Objectives • Provide evidence to the prospective Aviation users that a satellite based Air / Ground communication system can meet their most stringent requirements provided the correct design options are selected • SDLS Programme Phases • Key system performance demonstrator with AESs on ground (on-going with targeted completion third quarter 2002) • A full scale validation with airborne avionics and the participation of CAAs and airlines is in the planning stage • Industrialisation could immediately follow a decision by aviation to take advantage of SDLS to build an ICAO standard ICAO/AMCP WG C 2nd meeting

10. Conclusion So Far • Satellite appears to be very well suited for the Safety Communications of Aviation • Extended geographical coverage capability • High service quality levels are achievable with proven technology • Affordable costs • Difficulties Inherent to the Aviation Environment • Decisions tend to be taken only when forced by external constraints • Trial and error often takes precedence over theoretical analysis • Long term planning appears to be almost incompatible with the fundamentally political nature of international decision making processes • However ICAO/AMCP WG C 2nd meeting

11. SATELLITE DATA LINK SYSTEMSDLS It May Well Happen ! ICAO/AMCP WG C 2nd meeting

12. ICAO/AMCP WG C 2nd meeting