On-board regeneration processors for digital communication satellites

Three on-board regeneration processing schemes - decoding-encoding information bit stream (DEP), soft decision channel symbol (SDP), and hard decision channel symbol stream (HDP) - are analyzed and ranked with regard to performance in the above order. DEP achieves close to optimum end-to-end link performance without any change in the downlink requirement and, in addition, gives the satellite access to the information bit stream, which can be used in subsequent processing or switching. HDP is the least complex scheme, while DEP requires demodulation remodulation and decoding reencoding on board the satellites. Three categories of processors - radio frequency, channel symbol stream, and information bit stream - are defined, and concepts such as performance measure and linear repeater are examined.