Signal Detection Algorithms For MIMO Wireless Communication Systems

More and more communication systems adopt MIMO technology recently. It can obtain space diversity gain and spatial multiplexing gain simultaneously, which improves system's transmission reliability and spectrum efficiency. However, it's more difficult for MIMO system receiver to detect signal compared with SISO system receiver because of its multi-antenna. Signal detection has an impact on MIMO system's performance, so it has great theoretical and realistic significance to research on the topic. Based on this point, the thesis mainly discusses following issues.1. Summarize primary principles and processing flows of MIMO system's existed signal detection algorithms. Having analyzed and compared the BER performance and complexity of existed algorithms, the paper devotes to the solutions to their disadvantages.2. In order to improve the reliability of MIMO system with strong channel correlation, a lattice reduction aided QR decomposition detection algorithm based on MMSE is given from the angle of signal detection. The algorithm optimizes the base vector of channel matrix via lattice reduction technology, which makes it approximately orthogonal and have a shorter Euclidean distance, thus improve the receiving signal's reliability. Theoretical analysis and simulation results show that the algorithm can effectively reduce its complexity while having almost the same BER performance of ML algorithm. Also, BER performance improved by lattice reduction will be more obvious with highly relevant channels.3. For the error propagation problem of signal detection in Vertical Bell Lab Layered Space-Time MIMO system based on spatial multiplexing, an iterative V-BLAST detection algorithm based on local optimum criteria is given. The algorithm can enhance pre-detected signal's accuracy, and then alleviate negative influence of error propagation during interference cancellation procedure through iterative processing. Theoretical analysis and simulation results show that the algorithm's BER performance is improved greatly while keeping a tolerable complexity.4. Design and realize the traditional V-BLAST detection algorithm and the proposed iterative V-BLAST detection algorithm based on local optimum criteria on the IMT-Advanced Key Techonologies Simulation Platform developed by Xi'an Jiaotong University. Performances of the two modules are also evaluated, which further verifies that the BER performance of the proposed iterative V-BLAST detection algorithm based on local optimum criteria is better than that of traditional V-BLAST detection algorithm.