一种新的基于自适应步长的二级CMA盲接收机

摘要

In the direct sequence code division multiple access ( DS-CDMA) system with high data rate over frequency-selective channel, the two-stage blind receiver based on constant modulus algorithm ( CMA) can implement joint equalization and multiuser detection in DS-CDMA system over frequency-selective channel, while the real-time performance capability of it has been proved to be well. In the two-stage CMA adaptive blind receiver, however, the adaptive algorithm of the first stage's detector is based on Recursive Least Square (RLS) algorithm, and this algorithm has some shortcomings in robustness of convergence and so on, that will lead to the performance degradation of the whole adaptive blind receiver. In this paper, we substitute Recursive Least Square algorithm by DaiYuan ( DY) adaptive stepsize algorithm in the first stage's detector, and we also give the whole implementation scheme for our proposed algorithm. The theoretical analysis and computer simulation both show that our proposed algorithm outperforms the original algorithm, it has much lower bit error rate (BER) and much higher signal to interference plus noise ratio (SINR) .%在高速数据传输的频率选择性信道的直接序列扩频系统中,基于恒模算法(CMA)的二级盲接收机能够在只知道期望用户的扩频码以及定时信息的情况下进行自适应联合均衡和多用户检测,具有较好的实时处理性能.但是其第一级检测器的自适应求取采用的是递归最小二乘(RLS)算法,该算法在收敛稳定性等方面具有一系列缺陷,从而对整个算法的性能造成了损害.本文将戴彧虹-袁亚湘自适应步长迭代算法作为第一级检测器的自适应处理方式,并给出了新的方案的完整实现流程.理论和仿真结果显示,经过改进后的二级CMA盲自适应接收机比起原先的算法有着更低的误码率和更高的稳态输出信干比(SINR),在总体性能上有了很大提高.