Beam-forming Algorithm For TD-SCDMA System

Smart antenna is the key technology of TD-SCDMA system, which can increase communication system capacity and improve resource utilization of spectrum and so on. Adaptive beam-forming algorithm is the core of smart antennas. Based on the different space propagation direction of useful signals, it can adaptively control pattern and produce a higher gain beam in the direction of useful signals and form a zero settlement in the direction of interfering signals, and dynamically track the useful signals at the same time, so it can reach purpose that improve the signal to interference noise ratio of signal and lower transmission power. The various performance of some classical adaptive beam-forming algorithm are declining, and can not reach the requirements of communication in the actual communication environment. Therefore, the improved methods which can adapt and meet the performance requirements in these specific circumstances is the focus of this article.This paper first describes the basic theory of TD-SCDMA system, and introduces the basic concepts, working principle, classification and spatial structure of smart antenna. Second, it introduces the traditional LMS algorithm, RLS algorithm, NLMS algorithm and SMI algorithm, and studies convergence and beam-forming performance of these adaptive algorithms in different situations, then discusses fast LMS algorithm and improved RLS method according to existent problems. Then, aimed at features of TD-SCDMA base on CDMA technology, it studies and analyses blind beam-forming algorithm with respread despread technical characteristics in the application of the system, and discusses improved LS_DRMTCM adaptive array method based LS_DRMTCM adaptive array algorithm. It compares advantages and disadvantages through analyzing bit error rate and power gain and so on, and through the Matlab simulation, verify the improved method discussed in this paper is correct and effective under complex the conditions of input signals.Finally, it carries out a summary and prospect by the paper.