导　　师： 庄哲民

学科专业： 081002

授予学位： 硕士

作　　者： ;

机构地区： 汕头大学

摘　　要： 在CDMA/(Code Division Multiple Access码分多址/)通信系统中，由于多个用户的随机接入，所使用的扩频码集一般并非严格正交，码片之间的非零互相关系数将引起各用户间的干扰，这种干扰称为多址干扰。多址干扰的存在不仅会严重限制系统的容量，而且强多址信号会淹没弱用户信号。目前DS-CDMA通信系统主要采用功率控制技术来处理多址干扰问题，但该技术只能缓解多址干扰，无法从根本上解决多址干扰。为了能够有效的抑制CDMA移动通信系统中的多址干扰，多用户检测/(MUD/)技术的研究成为现在通信领域的研究热点。其主要思想是充分利用所有用户的信息对接收信号做联合检测，抑制多址干扰，缓解“远—近”效应，从而有效地提高系统容量。本文主要进行了以下两方面的研究。 首先，本文对现阶段在理论上比较成型的、性能接近最佳多用户检测的次最佳多用户检测理论进行研究，计算并分析常规单用户检测器、解相关检测器、最小均方误差检测器/(MMSE/)、最佳线性检测器的性能及参数指标。 其次，本文给出一种基于改进子空间跟踪的盲自适应Kalman多用户检测算法。在从理论上对这种算法进行分析的同时，且利用MATLAB作了系统性能的仿真。仿真结果表明，该检测器可以迅速地跟踪维数变化了的信号子空间，从而提高检测器的性能，实现稳定的跟踪并输出良好的信干比。 In CDMA mobile communication system, because of the multi-user's randomly connection,the spread spectrum codes they used are normally not quadrature rigidly. The nonzero crosscorrelation coefficient between codes will arouse the interference between the users, which iscalled Multiple Access Interference /(MAI/). The existence of MAI can severely limit the capacityof the system, and also make the strong signal submerge the weak signal. These days,DS-CDMA communication system mainly uses power control technique to restrict MAI, but thistechnique can only relax MAI, it can't solve MAI problem. In order to restrict MAI effectively,multi-user detection has become a hot research field in the communication system. The mainidea behind it is to make joint detection on the received signals by making full use of theinformation of all the users' signals, which eliminates the multiple access interference /(MAI/) andrelaxes the 'near-far' effect, and consequently increases the capacity of the system. This essaypresents a research of two parts. Firstly, the parameter and the performance of the conventional single-user detector/(CD/)、theoptimal multiuser detector/(OMUD/)、the decorrelating detector/(DD/) and MMSE blind multiuserdetectors have been analyzed in this paper. Secondly, a blind adaptive Kalman multi-user detection algorithm based on the improvedsubspace tracking has been proposed on this paper. Theory analysis of this algorithm and theperformance analysis of Matlab simulation are also given in this paper. Simulated results showthat it can follow the changing signal space rapidly and achieve better tracking SINRperformance while the channel changes suddenly.

关 键 词： 盲多用户检测 滤波器

分 类 号： [TN929.533]

领　　域： [电子电信] [电子电信]