一种利用ILSP的同步DS-CDMA信号快速盲解扩算法

An ILSP-Based Fast Blind Despreading Algorithm for Synchronous DS-CDMA Signals

针对同步DS-CDMA信号的盲解扩问题,本文提出了一种基于迭代最小二乘投影算法(ILSP)的快速盲解扩算法。本算法首先通过对截获信号的协方差矩阵进行特征分解,估计出由各用户扩频序列张成的信号子空间,然后结合扩频码序列的有限符号集特性,利用ILSP算法消除由特征分解产生的酉矩阵模糊问题,得到扩频序列的精确估计,最后利用估计得到的扩频序列对截获信号解扩得到信息码序列,完成DS-CDMA信号的盲解扩。仿真结果表明本算法在低信噪比条件下具有良好的盲解扩性能,且相较传统算法本文提出算法大大降低了计算复杂度。

In order to solve the blind despreading problem of the synchronous DS-CDMA signals,a fast blind despreading based on iterative least squares with projection(ILSP)is proposed.Firstly,the signal subspace spanned by the spreading sequences of all users is estimated via the eigen-decomposition of the intercepted signal covariance matrix.Then with the finite alphabet property of the spreading sequences,the ILSP algorithm is exploited to cope with the unitary matrix ambiguity resulting from the eigen-decomposition operation and estimate the spreading sequences accurately.Finally,the symbol sequences are obtained by despreading the intercepted signal using the estimated spreading sequences.The simulation results demonstrate that the proposed algorithm has good performance under the low SNR(Signal to noise ratio)environment and much lower computational complexity compared with the traditional algorithms.