Decision { Feedback Di erential Detection of MDPSKfor Flat Rayleigh Fading

In this paper, decision{feedback diierential detection (DF{DD) of M{ary diierential phase{shift keying (MDPSK) signals, which has been introduced previously for the additive white Gaussian noise (AWGN) channel by Leib et al. 1] and Edbauer 2], is extended to at Rayleigh fading channels. The corresponding DF{DD metric is derived from the multiple{symbol detection (MSD) metric and for genie{aided DF{DD an exact expression for the bit error rate (BER) of QDPSK (M = 4) is calculated. Furthermore, the dependence of BER on the power spectrum of the fading process is investigated for feedback lters of innnite order. It is shown that in this case, for ideally bandlimited fading processes the error oor of conventional diierential detection (DD) can be removed entirely. Simulation results connrm that both, MSD and DF{DD with feedback lters of nite order can reduce the error oor of conventional DD signiicantly. Thereby, DF{DD causes considerably less computational load.