Adaptive Beamforming Smart Antenna Algorithm Research And Design

The smart antenna is one of the key technologies of the contemporary mobile communication system. As the development of the third generation mobile communication system, the technology of the smart antenna is accepted as an advanced technology which introduces the pattern of SDMA to differentiate the signals with the same frequency, the same time slot and the same code but with the different transmission paths. The smart antenna can be used with other multiple access technologies, so the range of communication resource extends from time region, frequency region and code region to space region. As the result of the technology of smart antenna utilized, the capacity of communication system increase remarkably, and limited frequency spectrum resource will be utilized sufficiently.Adaptive algorithms for beam forming are used to produce spatial and directional beam in smart antenna. Then the main beam aims at the coming direction of desired user and the side lobe or null points to the coming direction of interference user, which is based on the spatial information of users, so the signal of desired user will be enhanced, the signal of interference user will be restrained, and the anti-noise ability of the system is remarkably developed.Adaptive method is to get the optimum weight vector throughout the alternate operation. If adaptive algorithms for beam forming can get more fast convergence speed and lower steady state error, the performance of beam forming will be better. In this paper, the research mainly focuses on the adaptive algorithm for beam forming. The following topics are covered as the content of this paper: Based on the system principle component of smart antenna, many kinds of beam forming criteria and algorithms are discussed in this paper. The convergence speed and the directional charts of them are compared. Three algorithms, which are realized easily, are put forward based on the characteristics of the TD-SCDMA system finally. The feature of this paper is not only to analyze and compare many tradition beamforming algorithms, but also link with the third generation standard of the TD-SCDMA. The topics of the data construction and the data flow are discussed to extract the possibility of the down link beamforming algorithms used on the TD-SCDMA system. The three different algorithms are based on the different traits of the TD-SCDMA system whose feasibilities are verified, and the algorithms are not only stay on the research of the theory, but also can be utilized in the project.The first part of the paper is the theory basis of the beamforming technology. The second part can be seemed as the reference of the beamforming technology realization of the TD-SCDMA system.