TheJournalofChinaUniversitiesofPostsandTelecommu：中国邮电高校学报的地位.docVIP

The Journal of China Universities of Posts and Telecommunications Vol. 4, No. 1, Jun. 1997 Chaotic Spread-Spectrum Communication Using Discrete-Time Synchronization* Wang Hai and Hu Jiandong (Department of Telecommunications Engineering, Beijing University of Posts and Telecommunications, Beijing 100088, P. R. China) Abstract 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 H(non 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. Key Words chaotic spread-spectrum communication, discrete-time synchronization 1 Introduction Chaos is a deterministic, random-like process found in non-linear, dynamical system, which is non-period, non-converging and bounded. Moreover, it has a very sensitive dependence upon its initial condition and parameter [1]. Chaotic signals can be used in communication. A chaotic map is a discrete-time dynamical system running in chaotic state. The chaotic sequence can be used as spread-spectrum sequence in place of PN sequence in conventional CDMA DS/SS communication systems [2]. Chaotic sequences are uncorrelated when their initial values are different, so in chaotic spread-spectrum systems, a user corresponds to an initial value. In addition, it is possible to synchronize two copies of a discrete-time chaotic system, in the sense that their state trajectories tend asymptotically to be identical when one system is suitably driven by the other. If the driving signal is selected appropriately, the discrete-time synchronization will be immediate [3]. In CDMA spread-spectrum system, how to attain the transmitter-receiver synchronization im-medi