On board multicarrier digital demodulation in regenerative satellites

In future satelliLe communication systems, regenerative repeaters will play an important role, since on board reyeneration decouples the upllnk and downlink transmission formats, 1. e., coding, modulation, and multiplexing. In some appl~cations, frequency dlvlsion multiple access in the uplink may be cost effective, provided efficient techniques for on board demodulation are available. In this paper only solutions based on digital signal processing are investigated, and the analysis is restricted to modulation formats that can be represented, at least approximately, as quadrature amplitude modulation (QAM), or offset QAM .