Cdma System In Multi-user Detection Techniques

In this thesis, the application of multi-user detection (MUD) in the CDMA system is investigated. Two aspects of MUD are mainly discussed: One is the blind adaptive multiuser detection technology, and the other is the application of MUD in the multi-path channel.Several representative multi-user detectors are recited before the main contents. Firstly, the concept of blind adaptive MUD is educed by the introduction of the MMSE detector requiring training sequences. Secondly, three kinds of algorithms blind adaptive multi-user detectors with the LMS, RLS, and KALMAN are discussed respectively by the theoretical analysis and the simulate results. Finally, the application of MUD in the frequency-flat slowly fading multi-path channel is introduced, and to enhance the system efficiency the joint use of the RAKE receiver and MUD is applied in the frequency-selective slowly fading multi-path channel.We can see that the KALMAN blind adaptive algorithm discussed in this thesis has the advantages of quicker convergence and better signal-to-noise rate. And the joint use of RAKE receiver and MUD has practical value too.