The Research On Coding And Decoding For MIMO Systems

MIMO technology is a key technology to the next-generation mobile communications. The technology can greatly improve spectrum utilization and bring high rate and quality of data transmission without increasing bandwidth. MIMO technology can give two types of gains: diversity gains and spatial multiplexing gains. Diversity gains can improve the quality of data transmission, while the multiplexing gains are used to increase the transmission rate of data. Zheng and Tse raised the concept of diversity and multiplexing tradeoff in 2003, from then the reasonable compromise between the two types of gains becomes the new metric to measure the MIMO systems, which measures the comprehensive utilization of diversity and multiplexing. Now the optimal tradeoff scheme is an active area in MIMO system.This thesis mainly studies deeply on the diversity-multiplexing tradeoff of typical coding and decoding scheme in MIMO systems. Firstly, the thesis introduces the principle of wireless MIMO system and the metrics of system diversity-multiplexing tradeoff and optimal tradeoff. Secondly, the thesis gives the typical linear decoding methods such as ZF, MMSE, SQRD and OSIC for MIMO systems. Then the thesis analysis the diversity-multiplexing tradeoff curve of these decoding methods. The result indicates that these methods have the same tradeoff relationship, but don't equal to the optimal tradeoff for MIMO systems. Besides, the thesis also studies the diversity-multiplexing tradeoff of typical coding methods. The result indicates that these coding methods don't achieve the optimal tradeoff as well, but the tradeoff curve of the rotation coding partly implements the optimal curve. Finally, the thesis presents the conditions that can achieve the optimal tradeoff curve for MIMO systems and try to construct coding and decoding scheme of optimal tradeoff, which is the main innovation of this article. On the basis of the optimal tradeoff and approximately universal communications, the thesis presents the conditions of optimal tradeoff in MIMO systems, and verifies the conditions. Then the thesis constructs a specific rotation coding scheme, and found that the scheme can achieve the optimal diversity-multiplexing tradeoff while using the improved MMSE-DFE joint decoding.