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

Author(s): SHU Xiujun; WANG Haibin; WANG Jun; YANG Xiaoxia;

Affiliation(s): Institute of Acoustics, Chinese Academy of Sciences, et al.

Abstract: Direct-sequence spread spectrum(DSSS) communication possesses low probability of detection and has been widely used in confidential communications.However,pseudo-noise(PN) sequences,used as spreading code in conventional DSSS communications,possess periodic character and binary value.In hostile environments,these distinct characters may lead to some important parameters of signals being estimated accurately,and then lead to the leakage of transmitted information.To solve the problem,we propose the chaotic phase modulation(CPM) sequence alternating the PN sequences.CPM sequence has complex values and constant envelope,and also possesses large quantity and good correlation characteristics.Moreover,it has more hidden features than conventional sequences by modulating its phases using chaotic sequence.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.