New recursive formulations of optimal detectors for Rayleigh fading channels

We investigate maximum likelihood sequence estimation (MLSE) of data sequences transmitted over time-varying frequency-selective Rayleigh fading channels. We present new recursive formulations for optimal detection in presence of a perfect channel state information (CSI) at the beginning of the data sequence or in complete absence of CSI. We then derive a reduced state-complexity solution based on per-survivor processing (PSP) techniques for both optimal detection schemes. Performance evaluations are also provided. In particular, we show that the optimal detector performance may be practically attained with PSP-based reduced-complexity detectors. Furthermore the considered receivers are shown to approach in several cases the lower bound of an exhaustive sequence search