Study On Multiuser Detections In MIMO-CDMA System

Studying of MUD methods of MIMO-CDMA systems and improving these algorithms are major objectives of this paper. The performance of bit error rate(BER)/signal-to-noise ratio(SNR), near-far resistance, computational complexity and algorithm robustness to time-delay estimating error are discussed. The system model of MIMO-CDMA system is given. The transmitting signal configuration and the receiving signal components are analyzed. Various MUD algorithms are analyzed under this system model. An algorithm of MIMO-CDMA systems based on linear SIC is proposed, which combines multistage linear successive interference cancellation and multi-antenna combining to deal with the output of the linear SIC. Its BER/SNR performance is analyzed. Considering the delay error of channel estimation, another method provides error correction of time-delay interference is proposed. This method achieves robustness to time-delay error of channel estimation. System-level simulation of MIMO-CDMA is established. Bit error rate performance of various MUD methods as well as the proposed time-delay error correction algorithm is analyzed.The delay error correction method for MIMO-CDMA system proposed in this paper introduces estimation and cancellation of the delay error residual signal. Simulation results show that the proposed method is less sensitive to delay errors than other MUD methods. Our proposed method can combat the near-far effects under the delay error conditions.