Matrix Transform-Based Signal Detection In MIMO-OFDM Systems

Today, wireless communication is one of the most active research areas. In order to achieve the requirements of modern communication, a fourth generation mobile communication systems have been proposed. The MIMO technology and the OFDM technology are key technologies in the fourth generation communication systems; Getting the two technologies together that can form the MIMO-OFDM systems. There are several key technologies, such as space-time signal processing techniques, simultaneous techniques, error correction techniques of channel coding, signal detection techniques, channel estimation techniques, adaptive techniques, in the MIMO-OFDM systems. Among them, as a key technology, the signal detection technology is one of the major research fields in the systems.In the communication systems, that getting a low bit error rate and low computational cost is the target of signal detection techniques. How to meet the computational complexity and detection performance better is a compromise in the signal detection technology area. That is, the computational cost with minimal access to optimal detection. This thesis outlines the formation of MIMO-OFDM systems and status signal detection algorithms in the systems, detection algorithm based on the traditional theory and some matrix transformations (such as recursive matrix, matrix decomposition, etc.) related theories. The main results are as follows:Firstly, fast recursive detection algorithms are studied. A fast recursive ML-OSIC algorithm which is based on V-BLAST MIMO-OFDM systems is presented. Through the complexity analysis, it shows that the algorithm can achieve signal detection with no loss of performance of ML-OSIC case, but can reach a lower computational complexity degree and a faster processing speed.Secondly, the signal detection algorithms which are based on QR decomposition are discussed. The principles and performances of some detection algorithms (such as the QR detection, iterative detection QR, QR-ML detection algorithm) are analyzed in the MIMO-OFDM Systems. By using the corner QR decomposition, a jointed detection algorithm which is based on the ML detection is presented, and the steps of the algorithm is given.