Research On The Channel Models, Capacity, Estimation And Implementation Algorithms For MIMO Wireless System

It is believed that the wireless MEMO technology will be one of the key ones that realize the high-speed broadband wireless Internet access networks in the future and has wide application prospect in the third generation (3G) or beyond third generation (B3G) mobile communications. It has mainly made further research on the related theories about four main aspects: channel models, channel capacity, channel estimation and implementation algorithms on the basis of others' research work, and a few new conclusions were derived in the dissertation. Moreover, on the one hand, the important results acquired by others were tested and verified, on the other hand, a number of new useful experimental results were obtained by a number of computer-aided simulations. The main contents of the dissertation are expressed as follows:In the first chapter are an introduction of the background and significance of the research in the dissertation, and the simple overview of the progress made in research and application of wireless MIMO technology at present. The main problems existed in the MIMO investigations are pointed out also.In the second chapter, a wideband MIMO channel model with multiple-tap was integrated according to the angle of departure of the transmitting signal and its spread angle, the angle of arrival of the receiving signal and its spread angle, power azimuth spectra, Doppler spectrum and the geometric construction of antenna array both sides of transmit and receive, on the basis of full research on the theories of space-time channel model proposed in the recent literature. Moreover, a simulation platform was established for wireless MIMO channel, and it was made the simulation of the integrated MIMO channel theoretical model by computer on the basis of specific parameters provided by the 3GPP standard Rl-02-0181 specifications. The simulation results are in accord with the practical situations. At same time, it was also investigated the impact of the position errors of multiple antennas both sides of transmit and receive on the correlation of antenna array, and the simulation results by computer are also given.In the third chapter, it was particularly analyzed the impact of the correlation between antenna arrays both sides of transmit and receive, the coexistence of line of sight (LOS) component and scatter power component in the radio propagation environments, and known and unknown channel state information on the capacity of MIMO channel. The related simulation results are also given. It was specifically analyzed the capacity for two kind of special MIMO channel (full "1" channel and orthogonal channel). The formulae for computing the capacity of the two channels were obtained, and the physical explanations about these formulae are also given in the thesis. At same time, a simulation platform was established for computing the capacity of wireless MIMO channel, and on the platform it was calculated out the cumulative distribution functions (CDF) of the channel capacity of the integrated MIMO channel model on the basis of specific parameters provided by the 3GPP standard Rl-02-0181 specifications. Some related results have been acquired after comparingthese CDF with the theoretical capacity.In the fourth chapter, It was at first estimated all the channel coefficients by maximum likelihood estimation and minimum mean square error estimation method on the basis of the construction of the transmission frame and the mathematical model for the wireless MTMO system of channel estimation with training sequence. When signal-to-noise (SNR) is low or high, the variances of estimation errors of the two estimation methods, which are above stated, were compared and analyzed. Secondly, It was.made theoretical analyses about the optimal training sequence design by the maximum likelihood estimation method and obtained the corresponding results, which were compared with the separate results derived by the minimum mean square error (MMSE) estimation method in the other literature. At last, it was analyzed the impac...