A differential space-time code receiver using the EM-algorithm

In this paper, we consider the detection of differential space-time block codes in static Rayleigh fading channels. Conventional differential detection (CDD), the most prevalent and most basic approach, suffers from a loss in performance when compared to coherent detection. As an alternative, we propose using 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. The EM-algorithm performs joint channel estimation and sequence detection. Employing BPSK modulation, simulation results show that the EM-based receiver outperforms standard ST-MSDD receivers after three iterations. The results in the paper demonstrate that our EM-based coherent receiver, using a non-coherent first pass, offers a reasonable performance improvement over standard non-coherent receivers.