Soft Decision Equalization of Multiple Antenna Systems over Dispersive Channels via Max-log-MAP Sphere Decoder

In this paper, we propose a multistage soft decision equalization (SDE) technique using max-log-MAP sphere decoder (MLMSD) for block transmission over frequency selective multi-input multi-output (MIMO) channels. Using the Toeplitz structure of the channel matrix, we convert the general signal model into a series of small-sized sub-signal models. We propose to use MLMSDs based on these sub-models to iteratively cancel interferences and get the estimations of the transmitted symbols. Simulation shows that when the block size is large, the proposed algorithm outperforms the Schnorr-Euchner sphere decoder and the probability data association SDE with a reasonable computational complexity in full-rank MIMO channels.