A Doa Method Based On Counteraction Of Interferences For Estimation Coherent And Multi-Path Signals In DS-CDMA System

Direction of arrival (DOA) estimation, which is developed from spectrum estimation, has wide applications in array signal processing. The smart antenna, which is adapted in the wireless mobile communication, forms an antenna with a high gain by using digital signal processing(DSP) technology. The communication in all directions can be proceeded. The space division multiple access(SDMA) is introduced in smart antenna, users can be distinct from each other through their special location. Therefore, the Direction of arrival(DOA) of each user plays a very important role in smart antenna.In real communication environment, signal transmits with multi-path. So, some general DOA estimation algorithms are invalid, and we should look for some especial algorithm. In this paper, we analysis signal model for multi-path environment. The author proposed a modified algorithm- a DOA method based on counteraction of interferences for coherent and multi-path signals-after analyzing the questions of the DOA estimation based on symbol-rate correlation matrices in DS-CDMA systems. The main work of the paper is in several aspects as follows:1. The fundamental concepts and theories of DOA in array signal processing are discussed, and the model of multi-path signals is set up.2. The principle of DS-CDMA system is demonstrated. The DOA estimation based on symbol-rate correlation matrices in DS-CDMA systems is discussed clearly, which based on the separation of sinals of interested serially, DOA's of each path are resolved accordingly. But the algorithm is very complicated, which takes too much time on calculating eigenvalue decomposition.3. In this paper, a new DOA estimation algorithm is presented, which separate the signals of interest by "spreading" twice, then, DOA of each path can be resolved serially by using Music algorithm. This new algorithm overcomes the limitation that the number of all the paths exceeds that of antenna array's elements, and also decreases the complexity dramatically. Simulation results confirm the effectiveness of the algorithm.