Multiple input multiple output (MIMO) systems could increase wireless communication system capacity enormously. The best optimal detection algorithm for MIMO systems was maximum likelihood (ML) detection algorithm, which could provide the best bit error rate (BER) performance for MIMO systems. However, the computational complexity of ML detection algorithm grew exponentially with the number of transmit antennas and the order of modulation, which resulted in difficult using for practice. A modified MIMO signal detection algorithm which combined ML detection with stack algorithm was presented in this paper. After performing QR decomposition of the channel matrix, the ML detection with length L was done firstly. The partial accumulated metrics were calculated and sorted, which produced an ordered set secondly. Based on the ordered set, stack algorithm was performed to search for the symbol with the minimum accumulated metrics. The proposed algorithm reduced the probability of look back in stack algorithm.

In multiple-input multiple-output wireless communication system, the order of symbol detection in Chase framework is critical because of error propagation. In order to improve chase detector’s performance, sorted chase detection algortihm to reduce error propagation is proposed here. By setting parameters at different values, trade-off between performance and complexity can be obtained properly. Simulation experiment results show the validity of proposed algorithm.

In order to get better trade-off between detection performance and calculating complexity, an improved detection algorithm was presented here. QRD-M algorithm is performed for several layers firstly, and successive interference cancellation detection algorithm was used to detect the bottom several layers parallel, and the candidate sequence with smaller PAM was selected out as the answer. Simulation results show the validity of proposed algorithm.