Application Research Of Muti-User Detection In 3G

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 have 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 Thus we can 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.In this thesis, we introduce the 3G system and the key technologies for 3G We emphasize on the technology of Multi-User Detection (MUD). We analyze the performance of LMMSE in various channels and prove that it can reduce the Multiple Access Interference and the multi-path interference and it has a good ability to resist the near-far problem. In this thesis, we also study the adaptive algorithm of MMSE and put forward the adaptive algorithm based on the pilot channel. Based on the sub-spatial algorithm, we analyze the blind algorithm and improve it by the part of the channel estimation.