Multiple access studies of multibeam communication satellites

The next generations of communications satellites are expected to employ satellite switched multiple spot beams to increase the system. The use of multiple spot beam systems in a packet switched environment with a large number of small bursty users is studied. A system is considered which achieves frequency reuse by using sub 2 nonoverlapping spot beams with sub T frequency translating transponders, where N sub T or = N sub 2. Promising system architecture are studied and six multiple access protocols are proposed to provide for the efficient use of the satellite channel; i.e., to reduce average packet delays while maintaining high throughput. Three of the protocol are based on a fixed switching sequence: the first uses a fixed station access technique, the second uses demand assigned station access and the third has a random station access. In the next protocol, station access slots and switch settings are both assigned on demand, on a packet by packet basis. The last two protocols assume buffering on board the satellite and the satellite operating as a store and forward node.