Adaptive QRD-M detection with variable number of surviving paths for MIMO systems

The QR decomposition based M algorithm (QRD-M) is a sub-optimal detection algorithm which can achieve a tradeoff between bit error rate (BER) performance and computational complexity for multiple input multiple output (MIMO) systems. In this paper, an adaptive QRD-M algorithm with variable number of surviving paths is proposed for MIMO systems. The number of surviving paths at each detection stage is adaptively determined according to the instantaneous value and the statistics of channel conditions. The required statistics of the channel conditions is directly derived and given in closed form without a large number of training observations. The proposed algorithm is simple to implement and it is verified by computer simulations that the proposed algorithm has lower computational complexity than the fixed QRD-M algorithms thus can offer a better tradeoff between BER performance and computational complexity.