Maximum likelihood sequence detection in nonlinear satellite channels

A technical study by computer simulation has been performed to assess the potential of maximum likelihood sequence detection (MLSD) in a band-limited nonlinear satellite channel with two nonlinear elements [a high-power amplifier (HPA) and a transponder traveling wave tube amplifier (TWTA)] operating in tandem. Starting with a brief background on digital modem development, this paper outlines the basic principle of MLSD and a conceptual structure suitable for satellite channel applications. The bit-error rate has been computed for a realistic nonlinear satellite channel using Forney's approach with the Viterbi algorithm. The upper bound of channel performance improvement in a typical satellite link has been identified.