Investigation On Interference Cancellation In TD-SCDMA System

TD-SCDMA was accepted as the third generation (3G) mobile system standard together with WCDMA and CDMA2000 together on 5th Nov. of 1999, which is proposed by China Academy of Telecom Technology (CATT). The Ministry of Information Industry of China released the inform of frequency plan of the third generation public mobile communication system, in which TD-SCDMA system was assigned 155 megahertz. This showed the support for TD-SCDMA from the government. Now the network for commercial is being tested, which indicates TD-SCDMA will play an important role in 3G of China. This paper is supported by national "863" program named the improvement and evolution of TD-SCDMA system. The purpose of this paper is to analyze the interference of TD-SCDMA system and investigate the algorithm of interference cancellation, so as to perfect the performance and speed the commercialization.The interference of TD-SCDMA system was analyzed deeply in this paper, including the intensity and the number of interference. Based on the analysis, two cancellation schemes are proposed, which change the severe adjacent cell interference (ACI) to intra cell interference and cancel the interference using multi user detection (MUD) algorithm. Simulation result showed that the schemes are effective for interference cancellation, especially for ACI. The schemes can also be adopted in TDD-CDMA system for cancellation of intra cell interference and inter cell interference, without change of system structure.In chapter 2, a thorough analysis on interference such as multi access interference (MAI), inter symbol interference (ISI) and inter cell interference of TD-SCDMA system is given, especially on same direction of slot assignment of adjacent cells. The formula of interference produced by mobile station (MS) of adjacent cell is given in this thesis. The distribution area of severe adjacent cell interference (ACI) is decided according to the power of interference. The number of ACI with omni antenna and smart antenna is estimated respectively. The difference of the number indicates the effect of interference...