Research On Optimization Of Multi-Antenna Technology In Wireless Communication

In the past ten years, mobile communication has been greatly developed. Because the resources of frequency domain, time domain and code domain can't meet the rapid growth of wireless internet data service, it becomes very important to enhance the spectral efficiencies of wireless communication techniques. The multi-antenna teachnology will be the most promising technique to solve these problems, since which can improve reliability and transmission rates achievable in wireless systems. Multi-antenna system includes smart antennas and Multi-Input Multi-Output systems.The key technology of multi-antenna involves the direction of arrival estimating, beamforming, spatial division multiple access, spatial multiplexing etc.In this dissertation, the fast estimation method of direction of arrival estimation,blind beamforming algorithm, spatial division multiple access, and the design of telemedicine system based on McWiLL/TD-SCDMA with multi-antenna are discussed. The main contents of the dissertation include:Firstly, the back ground, the information, and the contribute of the research are analysed.Secondly, the theory of number of signal soures, radio frequency location, direction of arrival, beamforming algorithm, spatial division multiple access ,the category and structure of smart antenna are discussed. Then, some innovation research works are made, which are as follows.Firstly, a fast method of direction of arrival estimation is proposed. Given the training sequences of a desired signal, the signal subspace and noise subspace can be obtain quickly, and the dimension of subspace can be correctly estimated at the same time. So the algorithms have less computational complexity. The effectiveness of the proposed approach is verified by numerical results.Secondly, a blind beamforming algorithm based on Non-stationary signal is presented to optimize the position and the deepth of null. The weight vectors of robust-constrainted adptive beamforming algorithm is modified. To improve the robust characteristics, nonlinear constraint method is used for optimizing the weight vector of adaptive pattern. The final solution of weight vector is different from alterably diagonal loading and the unknown parameter in optimal solution can be obtained easily and accurately. The signal-interference-noise rate of the new algorithm has robust characteristics for random steering vector errors and is not sensitive to power change of signal of interesting. Simulation results prove the validity of the new algorithm.Finally, to meet the development trend of tele-medicine system, a scheme oftele-medicine system based on McWiLL/TD-SCDMA provided by Datang Co.,China, is presented and the multi-antenna technology is adopted.