Improved Stack Algorithm for MIMO Wireless Communication Systems

The use of multiple antennas at both transmitter and receiver can increase wireless communication system capacity enormously. The optimal detection algorithm for MIMO system is Maximum likelihood detection (MLD) algorithm, which provides the best bit error rate (BER) performance for MIMO system. However, the computational complexity of MLD algorithm grows exponentially with the number of transmit antennas and the order of modulation. An improved MIMO detection algorithm which combined M-algorithm with stack algorithm was presented in this paper. The proposed algorithm was a multistage detection which was consisted with three parts: MLD, M-algorithm and stack algorithm. In MIMO communication system with in transmit antennas, after performing QR decomposition of the channel matrix, the MLD with length L was done firstly. The partial accumulated metrics were calculated and sorted, which produced an ordered set. Then selecting the first M partial symbol vectors to form a new ordered set. Based on the new ordered set, stack algorithm was performed to search for the symbols with the minimum accumulated metrics. The proposed algorithm combining M algorithm and stack algorithm reduced numbers of ordering with the original stack algorithm, the probability of look back and improving the detection performance.