Mimo-ofdm System Signal Detection Technology

Multiple Input Multiple Output can enhance spectral efficiency several times without increasing bandwidth. Orthogonal frequency-division multiplexing is a fine technique to mitigate the effort of frequency-selective fading. Therefore, the MIMO-OFDM system, which takes advantage of these two techniques, is a promising choice for future high-data-rate transmission over mobile wireless channels. The merits and complexity of the receiver detection technology has a direct impact on the quality of communications systems and applications.The focus here is signal detection of MIMO-OFDM system. First the principle of MIMO-OFDM is presented. Then introduces two kinds of MIMO-OFDM transmitter signal design schemes which named STBC-OFDM and SFBC-OFDM. and studies three detection algorithms, including joint maximum likelihood, zero-forcing and decision-feedback detectors respectively. Next introduces a MIMO-OFDM transmitter signal design scheme named VBLAST MIMO-OFDM and several kinds of signal detection algorithms are discussed, such as maximum likelihood, zero-forcing, minimum mean-sqrare error and V-BLAST algorithm. In order to reduce the computational complexity of V-BLAST algorithm, the sorted QR decomposition algorithm based on the ZF-OSIC algorithm and its relative algorithm named ZF-SQRD and MMSE-SQRD are studied. In the latter part, Simulations are taken to verify and compare the performance of each algorithm. Simulation results show that the proposed modified algorithms have better performance and their computation is greatly reduced.Finally, the sphere decoding algorithms are focused on. In order to reduce the computational complexity of the traditional algorithm, Improved algorithms are proposed from it, such as KCL, weighted KCL and CL-MMSE algorithm. The results of simulation show that the improved algorithms can achieve a high performance based on a low complexity.