The Rearch Of Blind Multiuser Dection Technology In CDMA System

In the CDMA system multiple users are housed in the same slot and the same band gap, but select a different address code.In practice, the address code can not possibly meet ideal conditions. when multiple users communicating, it will produce multiple access interference (MAI). With the changing number of users, multiple access interference has become the most important interference in CDMA systems. Multi-user detection technology is the full use of all user information to perform detection, suppress multiple access interference and increase system capacity. In practice multi-user detection algorithm is required to meet for both excellent performance and can meet the low complexity, while the natural existing multi-user detection techniques can not achieve balance between these two. Hence the need for more multi-user detection intensive research.First the article introduce multiuser detection theory and technology in DS-CDMA systems. Then the most primitive from to the traditional blind adaptive detector testing machines are introduced in the paper. The application and the application prospect of multi-user detection will be introduced in the paper, then the paper will do a specific comparison and analysis for linear blind adaptive multiuser detection algorithm. On this basis, the paper gives an improved prediction based compression approximation subspace tracking algorithm (iPASTd), as well as an improved forecast based on improved approximation algorithm for the compression (iPASTd) and the Kalman filter combining blind adaptive multi-user detector. Simulation results show that given the blind adaptive multiuser detection algorithm based on RLS blind adaptive multiuser detector, and based on LMS algorithm for blind adaptive multiuser detector compared with a good tracking performance, lower complexity, in the AWGN channel to obtain a good signal to interference ratio, and high SNR and strong near-far situation, this paper, blind adaptive multiuser detector can achieve a faster global convergence and good tracking performance.