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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 7 to 11 May 2001
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Satellite Data Link System
ICAO/AMCP WG C 2nd meeting 7 to 11 May 2001
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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 7 to 11 May 2001
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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 7 to 11 May 2001
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ICAO Requirement Summary for the Next 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 7 to 11 May 2001
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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 Geosynchronous Orbit (HEIO for the N polar cap) Capability for Highly Distributed Satellite 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 to 11 May 2001
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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 7 to 11 May 2001
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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 7 to 11 May 2001
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ICAO/AMCP WG C 2nd meeting
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 7 to 11 May 2001
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ICAO/AMCP WG C 2nd meeting
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 7 to 11 May 2001
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SATELLITE DATA LINK SYSTEM SDLS
It May Well Happen ! ICAO/AMCP WG C 2nd meeting 7 to 11 May 2001
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ICAO/AMCP WG C 2nd meeting
7 to 11 May 2001
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