Symbol detection in MIMO systems

Abstract

Multiple input multiple output symbol detection methods are observed under frequency flat fading AWGN channel condition. The modulation method employed is Quadrature amplitude modulation (QAM). The various symbol detection techniques are compared to observe their behavior under AWGN channel condition condition. Maximum likelihood (ML) symbol detection method gives the best performance but because of its high complexity it can’t be used. Sphere decoder reduces the complexity to some extent providing similar performance as ML estimate. The other methods used are Zero forcing and Minimum mean square stimation. These two methods when used successively for interference cancellation improves performance to large extent along with reduction in the cost. The technique employed for successive detectionis devised by bell laboratory hence it is called as V-BLAST method. Maximum a posteriori when used along with V-BLAST MMSE algorithm further improves the performance. These methods even works well under Rayleigh channel condition. Finally, the simulation results for performance of V-BLAST under both the channel condition are observed for all the symbol detection techniques. To increase the diversity for improved performance space time trellis code are employed. Their performance is observed for QPSK modulation scheme.