基于改进EASI算法的DS-CDMA信息码与伪码盲估计

针对直扩序列码分多址(DS-CDMA)系统多用户检测的问题,提出了一种基于性能指标(PI)变步长EASI算法信息码与伪码盲估计的算法.该算法在比较盲源分离(BSS)和DS-CDMA系统模型的基础上,用自适应的方法估计混合矩阵进而估计出伪码,并利用分离矩阵分离观测信号从而估计出信息码.另外,该算法利用PI值来调整步长,使算法收敛速度和稳定性能达到一个理想平衡点.实验结果显示,该算法具有很好的抗多址干扰(MAI)的能力,伪码和信息码的误码率分别在-10 dB和0 dB时达到10-2以下；对不同用户数,5dB时所有扩频码被完全正确检测的概率几乎都在80％以上.

Information and chip sequence blind estimation for DS-CDMA system based on improved EASI algorithm

To solve the problem of the direct sequence code division multiple access(DS-CDMA) system multi-user detection,this paper proposes a variable step-size EASI(Equivariant Adaptive Separation via Independence) algorithm based on PI(Performance Index) for information code and chip sequence blind estimation.Through comparing blind source separation(BSS) and DS-CDMA system model,the algorithm uses adaptive method to estimate the mixing matrix and then estimate the chip sequence.The demixing matrix is used to separate the observation signal,and then estimate the information code.In addition,the algorithm uses evaluation PI to adjust the step-size,which makes convergence speed and stable performance of the algorithm reach an ideal balance.The experimental results show that the algorithm has good resistance ability on multi-access interference(MAI).The bit error rate of the chip sequence and information code is below 10-2 in-10 dB and 0 dB respectively.To different user number,the probability of all PN codes estimated completely correctly is almost 80% above in 5 dB.