Generalized decorrelators for fading channels

An iterative pilot symbol aided detector for random multipath fading channels that does not neglect intersymbol interference (ISI) is studied for a CDMA uplink system with multiple receiver antennas. The algorithm resolves the received signals at each antenna into components corresponding to each path for every user. Estimated components are combined for obtaining the next sequence estimate for all users, and thus no signal energy is lost. Sequence estimation is based on convex set maximization of the likelihood function termed the generalized decorrelator approach. The continuous log-likelihood maximization technique used here is the expectation-maximization approach to parameter estimation for superimposed signals introduced by M. Feder and E. Weinstein (1988). Its resulting solution embodies an iterative non-quantized signal path estimator and an MMSE channel estimator.