Chaos Synchronization And Its Application In Secure Communication

Knowledge on chaos is one of important achievements in nonlinear science. With the further research of chaos, chaos control becomes an advanced research field. Chaos synchronization belongs to chaos control in general, and it has become important content of chaos control. Because chaotic signal has characteristic of broad bandwidth and like-noise, chaos has potential application in secure communication system. Through studying methods of chaos synchronization, this dissertation extends theoretical foundation and offers theoretical method of chaos synchronization and its application in secure communication. The main results are expressed as follows: Firstly, taking L u&& system as example, the dissertation adopts adaptive method to derive control laws and parameter adaptive laws based on Lyapunov stability theory in the condition that system parameters are unknown entirely, partly unknown with the sign is unknown, and partly unknown but the sign is known respectively. Secondly, considering that the realization of controller can't be realized exactly, synchronization of chaotic systems is achieved by variable structure control method when upper bound of the norm of uncertainty is known and unknown respectively. Thirdly, synchronization problems of discrete-time and continuous-time chaotic systems are studied. If the system is continuous, the time-delay is considered. The design problem of response system is investigated when it's in the ideal situation, there exist unknown parameters and disturbances, and controller is nonlinear due to physical realization limitations respectively. Synchronization of drive system and response system is obtained. Finally, chaotic secure communication system model is advanced based on the preceding conclusions, which make use of observer theory. This model adopts chaotic system as transmitter, uses chaos synchronization system according to observer theory as receiver, and recovers the information signal in the receiving end. The dissertation investigates chaos synchronization and its application in secure communication. Some new results are achieved, which is useful for further research.