| The third generation (3G) communication system is a brand new system which can meet the standard of IMT 2000/FPLMTS put forwarded by ITU. It is required that 3G system has a good net compatible ability and can realize the worldwide roam. It can offer the users not only the low-rate services but also the extensive multimedia services. Nov. 1998,China put forward the standard of TD-SCDMA that became one of the standard of RTT for 3G From then, our country began to have our own standard for 3G. So, we'd better take the advantage of this and devote to the research of key technologies of 3G It is very significant to improve our country's ability of competition in the communication market.Though there're many standards left for being chosen, it has already become the common understanding that the technology of CDMA will definitely be adopted in 3G and some key technologies are also the same. The key technologies for 3G include Multi-User Detection, Adaptive Antenna, RAKE Receive, Power Control and so on. These key technologies complement each other and all of them are the focus of present research. The advantages of the multiuser detection in mitigating multiple access interference (MAI) in CDMA systems were concerned within the worldwide in the recent years. The theory of multiuser detection is to detect one user's information by all the useful users' informaton fully. It has a good ability to reduce the interference in order to improve the system capability.In this paper we first study the infection of the rate of multiuser detection to the system capacity.Then, we learn the decorrelation detector and Minimum Mean-Square Error Detector from the theory. Then we emulate the two methods by MATLAB. From the result of emluator we know that multiuser detection can improve the system capacity and the two multiuser detection can reduce the bit error rate. But the MMSE detection has a better result than DEC detection. In last, the result of emluator is consistent with the theory by and large. |
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