多径环境下的直扩信号伪码周期估计

Period estimation of the PN sequence for direct sequence spread spectrum in multipath environment

针对低信噪比条件下多径直接序列扩频(直扩)信号伪码周期估计的难题,拓展了先前提出的单径环境下基于信号功率谱二次处理的方法,提出了在低信噪比条件下多径环境中直扩信号的伪码周期估计的二次谱算法。该算法首先对多径直扩信号求取功率谱,然后将所得到的功率谱作为一输入信号求其第二次功率谱,所得二次功率谱将在伪码周期整数倍处出现代表信号存在的尖峰脉冲,通过对这些尖峰脉冲间的距离进行检测就可以获得多径直扩信号伪码周期参数的检测估计。理论分析和计算机仿真结果表明:该算法可以有效地估计出多径环境下直扩信号的伪码周期,且估计性能和多径环境密切相关。

In this paper,an algorithm reprocessing of the power spectrum density is proposed to detect and estimate the PN sequence period of the multipath DS/SS signal in low SNR,which develops the previous processing method based on the single path environment. It can solve the difficult problem of PN sequence＇s periodic de- tection and estimation in multipath environment. In the algorithm,the power spectrum density of signals is firstly obtained,and then is treated as an input signal to compute its reprocessing power spectrum density; the power spectrum density secondly obtained appears peak pulses representing the signals＇ existence. Through detecting the interval of the peak pulses,we can obtain the periodic estimation of the DS/SS PN sequence of signals in multipath environment. Theoretical analysis and computer simulation results show that the proposed algorithm can effectively estimate the PN sequence period of multipath DS/SS signal, and that the estimation performance closely relates the multipath environment.