Recursive Detection of M-ary Signals over Fast Varying Mobile Communication Channel

Abstract

Abstrak IntroductionMultipath fading has a major effect on the performance of mobile communication systems. The time varying nature of the mobile wireless channel causes a limitation in the performance of the designed for non-fading channel even at high signal to noise ratio. Then, the development of mobile cellular resulted in increasing interest in the study of signal detection in the presence of this rapidly time varying environment. If the channel exhibits intersymbol interference (ISI) in the received data, adaptive equalizers [1][2][3], that use adaptive algorithms [4], are used to recover the received signal and to remove the ISI. When the channel is rapidly varying, tracking these variations becomes a challenging problem and hence the equalizer may not be able to track the channel.Several articles discuss the problem of detection of M-ary signals [5][6][7][8]. In [5] the authors derived an exact expression for the symbol error probability (SEP) for coherent detection of M-ary PSK signals using array of antennas with optimum combining. They consider a Rayleigh flat fading channel. In [6], a low complexity breadth first tree detector, termed improved M-algorithm (IMA) is proposed. The authors showed that IMA works well without an energy compacting front end prefilter (FEP) even in frequency-selective channels. Moreover, the authors propose to make use of the cepstrum to compute the FEP via a minimum phase target impulse response. In [7], the effect of power and rate adaptation on the spectral efficiency of orthogonal frequency division multiplexing (OFDM) systems using M-ary quadrature