A differential space-time code receiver using the expectation maximization algorithm

This paper considers the detection of differential space-time block codes in static Rayleigh fading channels. Conventional differential detection, the most prevalent and most basic approach. suffers from a loss in performance when compared to coherent detection. As an alternative, use of the sequence estimate provided by space-time multiple-symbol differential detection (ST-MSDD) to initialize an iterative receiver based on the expectation maximization (EM) algorithm is proposed. The EM algorithm performs joint channel estimation and sequence detection. Simulation results based on BPSK modulation show that the EM-based receiver outperforms standard ST-MSDD receivers after just three iterations. The results in the paper demonstrate that the proposed EM-based coherent receiver, using a noncoherent first pass, offers a reasonable performance improvement over standard noncoherent receivers.