On The Impact Of Correlation On MIMO Systems And Antenna Selection Algorithms

Multiple antenna wireless systems have attracted increasingly significant attention due to their high capacity and good immunity to the channel fading. Most research on MIMO have made the assumption that fading between antenna pairs is independent, however, correlation usually exist in practice due to small interval beteen antenna elements or poorly scattering environment. In this dissertation, we study the impact of spatial correlation on MIMO systems, specifically , on the capacity of MIMO,the performance of space-time diversity codes as well as the performance of layered space-time codes. A unified conclusion is proposed after three related theorems are given, which states the rank of the correlation matrix determines the degree of freedom while the eigenvalue spread determined the coding gain of the MIMO system. This conclusion possessed the merit of simplicity, generality as well as clear physical meaning.Antenna selection can effectively reduce the performance degradation under the highly correlated channels, also it can reduce the cost and complexity of the MIMO system. In this dissertation a fast algorithm of transmit antenna selection based on sorted QR decomposition is presented, whose advantage is demonstrated from both capacity and performance view. Simulation results show that our algorithm has near-optimal performance, while its complexity is far lower than the optimal algorithm.