基于循环平稳差异的直扩信号盲提取抗干扰方法

摘要

提出一种基于循环平稳差异的直扩信号盲提取抗干扰方法.针对源信号在统计域上的近似独立性,构建直扩通信盲源分离抗干扰模型,基于源信号的循环平稳差异,利用循环自相关函数的典型极值点定义一个用于区分直扩信号和干扰的二阶循环差异度特征参数,通过比较该特征参数的大小进行模式识别,提取出直扩信号而抑制掉干扰,达到抗干扰的目的.仿真结果表明:当信干比(SJR)为-40dB、归一化信噪比(NSNR)为9dB时,直接解扩/解调信号的误比特率约为IE-0.3,而本文所提抗干扰算法误比特率(BER)低至IE-3,可从强干扰中有效分离并提取出直扩信号.%This paper presents a cyclostationary difference-based anti-jamming method by blindly extracting direct sequence spread spectrum signal.Aiming at approximate independence among source signals,an anti-jamming model based on blind source separation is established for direct sequence spread spectrum communication.And then,by using typical extreme points of cyclic autocorrelation function,a characteristic parameter called second-order cyclic difference degree is defined based on cyclostationary difference to distinguish between direct sequence spread spectrum signal and jamming.Finally pattern recognition is used to extract expected signal and suppress jamming by comparing the values of characteristic parameter,so as to achieve the purpose of anti-jamming.Simulation results show that,when the NSNR (Normalized Signal to Noise Ratio) is 9 dB and the SJR (Signal to Jamming Ratio) is-40 dB,the direct de-spreading /demodulation signal achieves the bit error rate (BER) of nearly IE-0.3,while the proposed algorithm achieves the biterror rate of as low as IE-3,which can extract the direct spread signal from the strong jamming effectively.