Parallel detection of space-time codes by predictive soft interference cancellation

Multiple-input-multiple-output (MlMO) techniques promise huge capacity increase in fading channels. Group-wise space-time coding is a tradeoff between complexity and performance. In this paper, structure of particular component space-time code trellises is exploited using partial information from Viterbi decoder of the simultaneously decoded interfering component code. We have shown that calculating the a posteriori probabilities of different states of the encoder at each time, and predicting the conditional mean and covariance of interference for the next time index, the system performance is improved by soft interference cancellation. The word-error-rate (WER) performance improvement for a system with 4 transmit 4 receive antennas is 1.7 dB and 1.5 dB for 2-space-time codes with 8 and 16 states, respectively. In addition, the parallel structure does not have decoding delay as in successive interference cancellation and is highly modular for VLSI implementation.