Precoding In MIMO System With Imperfect Channel State Information

Precoding is a kind of pre-equalization technique in MIMO wireless communication system that suppresses the interference between users at the transmitter, using the channel state imformation (CSI). But for actual time-varying MIMO channels, there is imperfect CSI due to the channal state estimation errors. This will affect the performance of precoding.Firstly the thesis introduces some precoding algorithms, and simulation is carried out to compare their performance. Then the influence of channel estimation error to linear and nonlinear precoding algorithms is analysed in this paper.The bit error rate (BER) performance of two precoding algorithms are also simulated to confirm the analysis result. Considering the effect of channel estimation error, an improved THP precoding algorithm is proposed in this thesis, which uses the MMSE criteria and combines with Bayes's estimation theorem. Simulation results show that the proposed THP can effectively decrease the unfavorable influence caused by channel estimation error, and has better BER performance than traditional THP algorithm.