DESIGN OF MULTIBEAM SATELLITE COMMUNICATIONS NETWORKS REALIZED BY SS/FDMA

In the subchannel switched frequency-division multiple access (SS/FDMA) system, each transponder bandwidth is subdivided into several narrow bands named 'subchannels', and interbeam connections are established on a subchannel by subchannel basis. The SS/FDMA system makes it possible to construct a satellite communications network among multiple beams by using only one transponder per beam. This paper presents systematic design methods for such networks. First, a method to determine transmission parameters of the network, such as transmit power levels of respective carriers, is described. Objectives of the design method are to maximize the system capacity, and to minimize the average transmit power for one carrier. Results of example calculations are also presented for power-limited and bandwidth-limited networks. Next, a method to determine the number of subchannels is described for bandwidth-limited networks, which is an important parameter affecting the system capacity of the bandwidth-limited networks. Results of an example calculation taking account of uniform and nonuniform traffic distribution patterns are also presented.