一种多通道混沌调相扩频方式及其在水声通信中的应用

A method of multichannel chaotic phase modulation spread spectrum and its application in underwater acoustic communication

直接序列扩频通信是一种低检测概率通信方式,在保密通信中得到了广泛的应用。但该通信方式仍存在缺陷,其采用伪随机序列作为扩频码,而伪随机序列具有周期性和二值性等较为明显的特征,在敌对环境下这些特征可能被利用,使得直扩信号重要的特征参数被估计出来,进而引发信息泄露。针对这个问题,本文提出采用混沌调相序列代替伪随机序列,混沌调相序列是恒包络的复数值序列,可用数量多,相关特性好,而且克服了伪随机序列周期性和二值性的不足,具有更高的保密性。为了提高通信速率,将混沌调相序列与多通道技术相结合,数值仿真结果显示了该通信方式优异的误码率性能,表明该通信方式在水声通信中应用的可行性。

Direct-sequence spread spectrum （DSSS） comlnunication possesses low probability of detection and has been widely used in confidential communications. However, it still exists some defects. In conventional DSSS communica- tions, pseudo-noise （PN） sequences, used as spreading code, possess binary and periodic characteristics. These distinct characteristics may lead some important parameters to be estimated accurately and the leakage of information in hostile environments. To solve the problem, we propose the chaotic phase modulation （CPM） sequence alternating the PN sequences. CPM sequence is complex and has constant envelope, which possesses large quantity and good correlation characteristics. It also possesses higher security than PN sequence by overcoming the problem of periodicity and binary value. To improve the data rate, we apply it into the technique of multichannel communication. Simulation results show this scheme＇s superior bit error ratio （BER） performance, which demonstrates its feasibility in underwater acoustic communications.