Chaos Synchronization And Its Application In Secure Communication

Controlling chaotic systems has become a challenging subject of nonlinear science, due to the great potential of application. In this dissertation, the methods and designs of chaos synchronization are studied, based on the theory of nonlinear control and stability analysis, and are used in secure communication. The main content is as follows:(1) Study on synchronization control of chaotic systems(a) Synchronization control of low dimension chaotic systems. Based on the methods of the PC synchronization and the synchronization method of feedback, a mixed approach of chaos synchronization is gained and it shortens the time to achieve the system synchronization; generalized synchronization and unified chaotic system are introduced and the generalized synchronization of unified chaotic systems is realized.(b) Synchronization control of hyperchaotic systems. Using the theory of state observer and pole placement of modern control theory, the hyperchaotic synchronization of discrete-time and continuous-time chaotic systems is achieved.(c) The optimization of chaotic synchronization. Mainly the synchronization with the disturbed parameters is considered. Ameliorating the synchronization method of nonlinear feedback, choosing the right relation-function, the qualification of synchronization is gained and the robustness is enhanced; chaotic synchronization of continuous system for different system parameters is realized by the parameter adaptive and driving feedback.(2) Study on application of chaos synchronization to secure communication(a) Chaos marking. The realization of chaotic secure communication based on the method of interval synchronization-recalling memory is provided, and the signal can be recovered wholly and exactly.(b) Chaos modulation. Base on the theory of state observer, a new method of the hyperchaotic secure communication is presented. The synchronization of hyperchotic systems is achieved by scalar signal and it needn't calculate the Lyapunov exponents and security is advanced. It is prone to realize in fact with broad applicability.(c) Chaos shift keying(CSK). For the good property of auto-correlation of the unified chaotic system, the CSK about it is studied. The analysis and the numerical simulation whether there is noise or not in the channel have been achived.