Research On Chaos Synchronization And Security Communication

There are lots of chaotic phenomena in real word. Discovery of chaos is one of important achievements in nonlinear science. In this thesis, the problem of the chaos synchronization and its application to secure communication is studied. The detail is given as follows:(1) Basic concepts, main features, basic concepts, main features of chaos are discussed, theoretical foundations of utilizing chaos in communication system are investigated briefly, which are helpful for further research.(2) Parameter identification methods of chaotic system based on adaptive synchronization are discussed. The concept of synchronization and several kinds of classical synchronization method are given, then the parameter identification process of chaotic system based on adaptive synchronization is given. Parameter identification problem can be converted into optimization with a given index function. Finally the paper explains the whole process with discrete Henon system and continuous Lorenz system. Then paper introduces three optimization methods, namely, quasi-Gauss-Newton method, Hook-Jeeves method and conjugate gradient method, and utilizes these three optimization methods to realize parameter identification and synchronization with two kinds of chaos systems. The simulation results show that the conjugate gradient method possesses better performance.(3) The paper discussed the problem of security communication based on spatiotemporal chaotic system. First, the paper introduces the model of spatiotemporal chaos, and several kinds of spatiotemporal chaossynchronization methods, including drive signal synchronization method and variable structure control method. Then, a security communication scheme based on OCOML spatiotemporal chaos with driving signal synchronization method is developed. This method is robust to common attacking methods. DSP implementation is given using this scheme for speech secure communication.