A soft-decision state-space equalizer for FIR channels

A nonlinear equalizer for binary data transmission over finite impulse response channels is developed. It is based on a state-space description of the channel. The equations of the resulting algorithm resemble the equations of a Kalman hard-decision feedback equalizer, similar to the one of McLaughlin et al. (1989). However, the derivation of the equalizer differs significantly from the derivation of the Kalman algorithm. In particular, probability estimates of the received bits are incorporated. They can be exploited in several ways to improve the performance of the equalizer and of the complete transmission system. Simulations for a mobile radio channel show that the new equalizer is an alternative to well-established equalizers like the Viterbi or the conventional hard-decision feedback equalizer