Chaos Synchronization And Its Application In Secure Communication

As a phenomenon found in nonlinear dynamic system, chaos is deterministic and random-like. It exists in the world everywhere. With the deepening studying to the chaos phenomenon, the chaos control has become the front subject in this filed. Base upon the sensitive dependence of chaotic systems on their initial conditions, a large number of non-periodic, continuous broadband frequency spectrum, noise-like, but deterministic and reproducible signals can be generated, so chaotic technology is very useful for security communications. This dissertation has researched on the control of chaos synchronization and its application in communication. The detail is clarified as follows:First of all, the dissertation discusses systematically basic concepts, basic characters, primary models, theoretical problems of utilizing chaos in communication system, and establishes foundation to research systematically.Secondly, the paper discusses the problems of chaos synchronization. The main results are: (1) a kind of synchronization technique is presented based on variable structure system control theory. In this scheme, the noise of the channel and the uncertainties of the system are considered. (2) Considering the applications of chaos synchronization in secure communication, an identical chaotic systems synchronization methodology is studied. An arbitrary signal, generated by an unknown dynamical system, can be synchronized and stored by the identical chaotic systems. By constructing an observer of chaotic system, considering the parameter disturbance and noise, the method that could be used for both chaos synchronization and secure communication is given, and furthermore its stability is analyzed. Numerical examples illustrate the accuracy and high performance of the proposed method for chaos synchronization and secure communication.Finally, considering the existence of random disturbance, we realize the chaos synchronization based on the state observer. Regarding chaos system as the transmitter and the chaos synchronization system as the receiver, the receiver can recover the transmitted signal in the ideal and parameter disturbance situations. Numerical examples illustrate that under certain conditions the signal can be recovered, so the effectiveness and efficiency of the proposed secure communication scheme are concluded in the end.The dissertation investigates chaos synchronization and its application in secure communication, the results of these researches will be useful in the future.