Research On Control Technology Of Multiplexing And Diversity Gain In MIMO

High-data and better QoS (Quality of service) and larger network capacity are essential of future wireless communication. In this condition, Multi-input Multi-output technology has become most competitive technology. In MIMO technology, space-time code is a technology which intergrates space diversity with channel coding.the intergrating create a new era of wireless communication and it offers solution of reliabale high speed wireless communication. This paper researched on coding technology of MIMO in controling diversity and multiplexing. The follow questions are discussed in the paper.1. The paper researched on MIMO channel models and channel capacity. The channel modeling based on correlation matrix and deterministic modeling based on radiation and scattering modeling based on geometry are analysed deeply in this paper. We have deduced the capacity of channel in different situation of channel coefficient. In this paper, it has been proved that the multiple-input multiple-output (MIMO) system can significantly multiplied channel capacity without additional bandwidth or power. What’s more, the research on channel model is helpful for the research of MIMO coding technology and it make sure that the following research work can be carried out fluently.2. MIMO space-time code technology is researched and analyzed deeply in the paper. The following question is discussed in this part.The basic theroy and launch scheme of Alamouti are researched in the detailed formulas and verified by simulations. As we known, Alamouti is suit for2transmitters and the space-time block coding scheme is suit for any amount of transmitters. So STBC scheme which is suit for any amount of transmitters and quasi-orthogonal space-time code are also discussed. What’s more, the paper discusses the shemes1perfomance in diversity and multiplex of system.3. The QOSTBC scheme can make multiple signal constellation symbols realize maximum transmission code rate even in only2transmitters. However it will increase the algorithm complexity.according to this situation, a new QOSTBC is proposed by this paper based on the analysis and study of the current quasi orthogonal space-time block code. The scheme uses the improved Alamouti Code as its basic unit to design a quasi orthogonal space time block code matrix with four tranmit antennas, using the method of matrix diagonalization to remove the redundant sparse matrix and reduce the decoding complexity.4. The layered space-time(LST) code’s structure and method are Linear BLAST researched in this part. The key research contents of this part are linear Bell Laboratories layered space-time(BLAST) detection algorithm and non-linear BLAST detection algorithm. By the detailed formulas and simulations, it indicate that linear BLAST detection MMSE algorithm which considers noise suppression is better than ZF algorithm, and non-linear detection algorithm which use interference offset method can effectively suppress the error propagation by iterative decision feedback.5. Especially, MIMO-OFDM coding technology is researched in the paper. The key research contents of this part are the detailed formulas and simulations of STBC-OFDM and SFBC-OFDM. By the comparison between them, STBC scheme realization and multiplex are discussed and simulated the SFBC in Jakes channel.The simulation indicate that MIMO-OFDM system which using SFBC can effectively suppress interference of time-varying channel and decrease the ratio of system errors.