Decision-feedback differential detection based on linear prediction for MDPSK signals transmitted over Ricean fading channels

In this paper, linear-prediction-based decision-feedback differential detec tion (DF-DD) for M-ary differential phase-shift keying (MDPSK) signals tran smitted over Ricean fading channels is proposed. This scheme can improve co nventional DD significantly for a multitude of frequency-nonselective chann els, as will be shown analytically and by computer simulations, Prediction- based DF-DD is particularly well suited for application in mobile communica tions since the predictor coefficients may be updated regularly using the r ecursive least squares (RLS) algorithm. Here, adaptation can start blind, i ,e,, no training sequence and no a priori knowledge about the channel stati stics are required. A further important characteristic of the proposed dete ction scheme is that no degradation occurs under frequency offset. The bit error rate (BER) performance of QDPSK with genie-aided prediction-based DF- DD is analyzed, and it is shown under which conditions the irreducible erro r floor of conventional DD can be removed entirely, In addition, the influe nce of Doppler shift is discussed. Last, the proposed scheme is compared wi th a second DF-DD scheme, which is based on multiple-symbol detection.