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 ...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 peri- odic 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 communica-tion. Simulation results show this scheme＇s superior bit error ratio （BER） performance, which demonstrates its feasibility in underwater acoustic communications.展开更多
The statistic characteristics of chaotic sequences generated by improved logistic map are analyzed and it is found that improved logistic map chaotic sequences have good correlation and they can be used as address ...The statistic characteristics of chaotic sequences generated by improved logistic map are analyzed and it is found that improved logistic map chaotic sequences have good correlation and they can be used as address sequences in spread spectrum communication. The discrete time synchronization of Henon map is immediate. We apply the discrete time synchronization to chaotic spread spectrum communication and propose an original communication scheme. The simulation shows that the application is successful.展开更多
文摘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 peri- odic 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 communica-tion. Simulation results show this scheme＇s superior bit error ratio （BER） performance, which demonstrates its feasibility in underwater acoustic communications.
文摘The statistic characteristics of chaotic sequences generated by improved logistic map are analyzed and it is found that improved logistic map chaotic sequences have good correlation and they can be used as address sequences in spread spectrum communication. The discrete time synchronization of Henon map is immediate. We apply the discrete time synchronization to chaotic spread spectrum communication and propose an original communication scheme. The simulation shows that the application is successful.
