The performance of MLSD receivers on nonlinear satellite channels

Abstract

This paper evaluates the performance of maximum-likelihood sequence detection (MLSD) receivers for nonlinear bandlimited satellite channels which employ QPSK and 8-PSK modulation formats. The optimal receiver for a nonlinear satellite channel is a matched-filter bank followed by a Viterbi detector (MFB-MLSD). The MFB-MLSD receiver may be high in complexity, where the filter bank complexity grows exponentially with the channel memory. Consequently, a suboptimal single receive filter receiver (SF-MLSD) is considered, and the effect of the pulse shape on channel memory is also studied. A finite-state machine (FSM) description of the channel is used for evaluating the nonlinear satellite channel. For all cases considered, the MFB-MLSD receiver gives a small performance loss compared to the AWGN channel, and the SF-MLSD receivers, when square-root raised cosine pulse shaping is employed, give little performance loss relative to the MFB-MLSD receivers.