A channel model and a novel adaptive equalizer for mobile radio communications

Abstract

The paper presents a multi-ray channel model and a novel reduced-state soft decision feedback Viterbi equalizer (RSSDFVE). The channel model can implement any channel impulse response which is required in mobile communications and the distribution functions of channel parameters can be chosen according to the environment. The authors use a 5 ray channel model for the simulation in the paper. For mobile radio channels with severe ISI, a Viterbi equalizer needs to handle both postcursors and precursors, like a decision feedback equalizer (DFE) having both linear and feedback filters. The authors propose an equalizer using maximum likelihood sequence estimation (MLSE) to handle precursors and which truncates overall postcursors with the soft decision feedback of MLSE to reduce the implementation complexity of Viterbi equalizers. According to the simulation results, the proposed equalizer gives nearly the same performance as MLSE in the presence of severe selective multipath fading with much less implementation complexity than MLSE. >