The Application And Research Of Multi-user Detector In The CDMA System

In CDMA mobile communication system, because of the multi-user's access, the spread spectrum code they used are normally not quadrature rigidly. The nonzero cross correlation coefficient between codes will arouse the interference between the users, which is called multiple access interference (MAI). The existence of the MAI will not only restrict the capacity of the system but also submerged the poor signal. So MUD is becoming into the hotspot in the communication research.Firstly, the multi-user detector that relatively integrity in theory and proximal to optimal multi-user detector is discussed and Decor elating Detector(DEC), Minimum Mean Square Error Detector(MMSE), Optimal linear Detector together with the multi-capability indexes (output energy, SNR, bit error rate, asymptotic efficiency, convergence etc.) are studied and analyzed in this thesis.Secondly, simulated and compared all kinds of capability indexes within the single user detector, traditional detector, DEC and MMSE detectors. The results indicated the DEC and MMAE detectors have a better convergence capability. At the same time, the SNR and the BER achieved a perfect effect.Lastly, on the base of deep research of linearity multi-user detector, analyze and plentiful simulate the blind multi-user detectors based on the signal subspace in MATLAB. Along with the analyzer in the theory, did some kinds of simulations. The result indicated that this arithmetic has a good result about SNR and BER. At the same time, put out some views on the future.