Joint Parameters Estimation and Symbols Detection for Digital Communication overLinear or Nonlinear Unknown Channels

摘要

An iterative method for joint channel parameters estimation and symbols detectionvia the Baum-Welch algorithm, or equivalently the expectation-maximization algorithm, is presented. Channel parameters, including noise variance, are estimated using maximum likelihood criterion. Estimates are obtained through the iterative maximization of a function related to the Kullback-Leibler information measure. The Markovian properties of the channel state sequence can calculate the required likelihoods using a forward-backward algorithm. The calculated likelihood functions can give optimal decisions on information symbols which minimize the symbol error probability. The proposed receiver can be used for both linear and nonlinear channels. It improves the system throughput by making savings in the transmission of known symbols, usually employed for channel identification. Simulation results which show fast convergence are presented.