Research On Synchronization Of Chaotic System And It's Application In Secure Communication

With the widely use of the computer and various communication network, secret communication becomes a new researching focus in the science fields of computer communication, network, application mathematics, micro electronics and so on. Chaotic motion is a complex nonlinear motion, whose trajectory of the orbits in the phase plane is very complex but not stochastic, and can be observed in fairly simple dynamical systems. Chaotic signals are ergodicity, aperiodic, uncorrelated, board band and noise-like. These are properties that coincide with requirements for signals applied in communication systems, in particular for spread-spectrum communications, multiuser communications, and secure communications. In all the areas, there can be observed an ongoing and growing research interest.The main content of this paper contains the analysis of the synchronization of continues-time chaotic dynamical system and it's application on secret communication. The synchronization of two continues-time chaotic systems can be attained by several methods, such as observer-based approach, linear matrix inequality-based approach, extend state observer (ESO) combined with nonlinear feedback control, state observer combined with nonlinear feedback control. The chaotic masking and chaotic modulation have been developed for synchronized chaotic communication system. The main contributions are as following:1. A system theory approach is introduced to design the encryption function and the decryption function. We present two hyperchaotic secure communication schemes based on state observer. The first one based on the full-order state observer. The method conbines choatic masking and chaotic modulate. The utilization of hyperchaos-based cryptosystems, as well as the increased complexity of the transmitted signal, make a contribution to the development of communication with higher security. The second one, based on the reduced-order state observer .The hyperchaos is used in the two-channel communication scheme: an output of the chaotic transmitter is sent for synchronization-only, while the other channel transmits a signal generated from a highly nonlinear function of the chaotic states and the information-bearing signal. Due to the hyperchaos and the separation of the synchronization and the encryption of the information-bearing signal, the security of the communication is improved.2. Research on the chaotic synchronization based on Riccatic inequality and it's application in communication. Based on Lyapunov stability theory, we proved that the problem of chaotic synchronization was equivalent to the resolve of a Riccatiinequality. Using adaptive theory, we prompted a kind of adaptive identification method of uncertain parameters. The parameter identification method and the resolve of Riccatic inequality were used in the synchronization of uncertain chaotic dynamical systems. The condition of chaotic secure communication was studied using the concept of severe positive real function. Furthermore, two methods are used in the chaotic secure communication, one is the communication combines chaotic masking and chaotic modulate, another is the two-channel communication.3. Research on the chaotic synchronization for systems with structure and parameters mismatching and it's application in communication. The parameter dynamic determinate method is used to design the nonlinear extension state observer. The arbitrary orders nonlinear ESO can be designed with this method. Applying nonlinear differential geometry, chaos synchronization via feedback is presented. To make this controller practicable, an extended state observer is used to estimate system information of the transmitter and receiver. Furthermore, two methods are used in the chaotic secure communication, one is the communication combines chaotic masking and chaotic modulate, another is the two-channel communication.4. Research on chaotic synchronization based on nonlinear feedback control and it's application in communication. Through theoretic proving, we found that the chao...