基于最小误码率准则的多载波CDMA系统多用户检测算法

Multiuser Detection Algorithm Based on Minimum Bit Error Rate Rule for Multi-carrier Frequency CDMA System

本文介绍了一种将正交频分复用(OFDM)技术和码分多址(CDMA)技术相结合的多载波CDMA(MC-CDMA)系统,分析了MC-CDMA系统的发射端和接收端的结构,建立了MC-CDMA系统的信号模型,详细分析了MC-CDMA中的多址干扰形式,以及针对MC-CDMA系统的多用户检测原理,提出了一种基于最小误码率准则的多用户检测算法。理想的基于最小误码率准则的多用户检测算法在实际中难于实现,本文采用估计概率密度函数的方法,推导出了一种自适应实现的最小误码率多用户检测算法。仿真结果表明,该算法能够有效抑制多址干扰,降低误码率,同时,该算法还具有比基于最小均方误差准则的多用户检测器更低的误码率的优点。

With the development of mobile communication technology,the data transform rate becomes higher and higher,this means that the period of code needs to be smaller and smaller,which will lead to a serious Inter Symbol Interference（ISI）.For the requirements of high rate data transform,a Multi Carrier frequency Code Division Multiple Access（MC-CDMA） technology is introduced in this paper,it is the combination of OFDM and CDMA.The structures of transmitting and receiving for MC-CDMA are analyzed,and the signal model for MC-CDMA is built.The multi access interference and the theory of multiuser detection for MC-CDMA are analyzed in detail in this paper.Based on the minimum bit error rate rule,a multiuser detection algorithm is proposed.The ideal minimum bit error rate multiuser detection algorithm is difficult to be performed in practice.We use a method to estimate the probability density function, and then derive an adaptive minimum bit error rate multiuser detection algorithm.The simulation results demonstrate that the proposed algorithm can suppress multi access interference and reduce the bit error rate.Furthermore,this algorithm has the advantage of lower bit error rate than the algorithm based on minimum mean square error rule.