Soft-decision feedback equalizer for continuous phase modulated signals in wideband mobile radio channels

A combination of a decision feedback equalizer (DFE) and a Viterbi processor for the equalization of continuous phase modulated (CPM) signals transmitted over wideband mobile radio channels is described. The equalizer structure allows soft-decision to be made and incorrect decisions to be changed in the feedback filter of the DFE. The provision of soft decisions significantly alleviates the catastrophic effect of error propagation due to error bursts caused by the fading channel. Simulation results show that the proposed equalizer approaches the performance of the more complicated maximum likelihood sequence estimation (MLSE) detector to within 2.0 dB and 2.5 dB at bit error rates (BERs) of 10^-2 and 10^-3 in a two-path Rayleigh fading channel while the complexity is reduced to half of that of the MLSE detector