EM algorithm for sequence estimation over Gauss-Markov ISI channels

This paper presents a new algorithm, based on an EM (expectation-maximization) formulation, for ML (maximum likelihood) sequence estimation over unknown ISI (inter-symbol interference) channels with random channel coefficients which have a Gauss-Markov fast time-varying distribution. By using the EM formulation to marginalize over the channel coefficient distribution, maximum-likelihood estimates of the transmitted sequence are obtained. This EM algorithm is shown to perform better, in terms of BER, than existing algorithms which perform jointly-optimal sequence and channel estimation, or which do not take into account fast time-varying channel effects.