Research On Key Technology Of Indoor MIMO System

This paper studies on the spatial correlation between channel and channel capacity in MIMO wireless system, analyzes the relationship between spatial correlation and several parameters, such as angle spread, antenna spacing. And these conclusions have guiding significance for better application of MIMO technology in indoor environment. This paper has also covered the performance simulation analysis of the receiver detection algorithm in MIMO system, this provides theoretical basis to further put forward the high efficient and low complexity algorithm.First, this paper establishes a kind of MIMO spatial correlation channel model based on correlation matrix method. The model considers the two main space channel parameters, one is angle spread (AS) that is described with power azimuth spectrum (PAS), the other is antenna spacing. From the simulation results can conclude, under Rayleigh fading channel, the correlation coefficient between antennas is directly related to antenna spacing and angle spread. Generally, the greater angle spread and antenna spacing, the smaller correlation coefficient, in contrast, the greater correlation coefficient, and the larger spatial correlativity can cause channel capacity loss.Secondly, the paper discusses a small scale decline indoor MIMO channel models: Rice fading channel, which includes LOS (line-of-sight) and NLOS (non line-of-sight) propagation environment. Through the simulation predicts the performance of the model, and analyzes the direct component, scattering component, and rice factors on the influence of channel capacity. With the increase of rice factor value, channel capacity of MIMO system reduces under low-rank channel matrix of direct component.Finally, V-BLAST (Vertical Bell Laboratories Layered Space-Time coding) system is introduced, which is the most representative in MIMO system, and this paper analyzes several detection algorithm performance by Matlab simulation. Assuming that under ideal channel estimation, Maximum likelihood (ML) algorithm has optimal detection performance, but it also has high algorithm complexity, so it is difficult for the application in practice. Although algorithm complexity based on zero forcing (ZF) and minimum mean square error (MMSE) rule is lower, but their detection performance is poor. And performance and complexity of detection algorithm based on serial interference cancellation (SIC) thought are moderate. When the number of sending and receiving antenna is four, the performance of this algorithm is better than the number of sending and receiving antenna is two.