A new adaptive equalizer with a channel estimator for mobile radio communications

Abstract

For unknown mobile radio channels with severe intersymbol interference (ISI), a maximum likelihood sequence estimator needs to handle both postcursors and precursors, like a decision feedback equalizer (DFE) having both linear and feedback filters. Consequently, such an equalizer is too complex to be practical. The paper presents the performance of a new reduced-state soft decision feedback Viterbi equalizer (RSSDFVE) and a modified reduced state sequence estimator(RSSE) with a channel estimator and predictor. Two profile Rayleigh fading channel models with a Doppler frequency shift are used in the simulation. In order to update the RSSDFVE and RSSE to track the changes of fading channels, different channel estimation techniques are discussed in this paper. The simulation results are compared with a recursive least square (RLS) decision feedback equalizer (DFE) and a maximum likelihood sequence estimator (MLSE).