Several Important Questions Research In MIMO System

Multiple-input multiple-output (MIMO) technology is a significant breakthrough in the development of wireless communication technologies. It can get rid of the constraint of radio frequency resource and greatly increase the spectral efficiency of wireless systems, and thus is considered as the future development trend of wireless communication technologies.However, MIMO technology thoroughly breaks the mode of traditional wireless communications, since it requires multiple transmit and receive antennas to simultaneously transmit and receive data information in the same frequency, which challenges all the aspects of wireless communications including system architecture, analytical methtods, modulation, coding, detection, channel estimation, multiple access, and so on.In this paper, research work, at home and abroad on the basis of MIMO wireless communication system for the theory involved in a number of key technology and conducted in-depth research, has been made on progress such as the MIMO channel capacity theory, based on the spatial diversity of the space-time code and based on the space division multiplexing space-time code, based on the decomposition of the subspace SIMO-OFDM system blind channel estimation and based on the decomposition of noise subspace MIMO-OFDM system blind channel estimation and so on. The major work done by the following:1. In the MIMO channel capacity theoretical side, has given the MIMO channel capacity and the approach simple closed formula.2. Has analyzed three space-time coding system in the performance of MIMO in the AWAG channel and the Rayleigh channel. With ZF, MMSE, ZF-SIC and MMSE-SIC four kind of examination algorithms have carried on the examination analysis to V-BLAST.3. In SIMO-OFDM blind channel estimate aspect, use signal subspace's maximum characteristic value correspondence's eigen vector and the noise subspace's smallest characteristic value correspondence's eigen vector carries on the channel estimate,and the simulation has compared their estimate error rate.4. In the SIMO-OFDM blind channel estimate's foundation, has conducted the thorough research to the MIMO-OFDM system blind channel estimation.In this paper,to provide a bandwidth-effcient solution for MIMO-OFDM channel estimation , we establish conditions for channel identifiablity and present a blind channel estimation technique based on a subspace approach.