Spectral Sharing in Hybrid Spot and Area Coverage Satellite Systems via Channel Coding Techniques

Multiple spot beam communication satellites offer the potential for greatly increasing the traffic handling capability relative to wide-area coverage systems, since the allocated spectral band can be reused in the various spot beams.1,2 A high-level block diagram of the satellite transponders for such a system might appear as shown in Fig. 1. Here, the various service regions are interconnected via an on-board switching matrix operating in the time-division mode, and digital modulation techniques consistent with time-division multiple access (TDMA) are employed. As previously noted,3 such a system suffers a serious drawback in that a large blackout region, serviceable by none of the spot beams, is created. The situation is depicted in Fig. 2, which shows the radiation footprints of a hypothetical 11-beam private line system serving the large population regions in the United States. Although most of the traffic load for 2613 TRANSMITTER 1 ER 2 RECEIVER N TRANSMITTER N Fig. 1--Satellite transponder.