Space-time decoding using a modified LMMSE algorithm

Iterative decoding has been proposed to improve the performance of multiple-input, multiple-output (MIMO) systems, where extrinsic information is passed between the space-time decoder and the channel decoder. A linear minimum mean-squared error (LMMSE) estimator accepting a priori information has been proposed as an equaliser for single antenna systems and in this paper we discuss its use as a space-time decoder. We also derive a novel modification, called the self-iterating LMMSE decoder, and present simulation results. It is shown that this modified LMMSE decoder can achieve huge gains over the conventional LMMSE decoder. Also both LMMSE decoders can supply a significant gain with iterative decoding, and with enough diversity and iterations, their performance approach that of the optimal decoder.