An access protocol for mobile satellite users with reduced link margins and contention propability

German Aerospace Agency (DLR), Fraunhofer FOKUS.cats, and Tesat-Spacecom have designed a future multimedia ATM-based LEO satellite network. Part of the development was an adaptive MAC and FEC scheme which are presented in this paper. The MAC protocol reduces contention while the FEC scheme guarantees a maximum ATM cell error rate of 10-6 even in the presence of rain. FEC and MAC were implemented in a prototype which was finally used to conduct measurements evolving some fundamental results for the design of future, satellite based, multimedia communication systems. These learned lessons concern the impact of shadowing, rain attenuation, and TCP's maturely when being used over variable propagation delay links