The Design Of Chaotic Spread Spectrum Sequence And The Application Researches On The Spread Spectrum Communication

Chaos is the non-linear dynamic system with characteristics of universality, certainty and similar randomness. In 1990, Pecora and Carroll realized the chaotic synchronization successfully at the first time. Subsequently, people became enthusiastic about generating good chaotic spread sequences by making use of the special properties of chaos. Because of the sensitivity to original value, the chaotic systems can generate abundant spread sequences which also possess characteristics of similar randomness but certainty. Chaotic systems can provide highly complex and secure chaotic sequences which are realized with simplicity. And so far, the researches on the chaotic sequences, have much more theoretical sense and application value, have become a academic hotspot and forefront project at home and outside.In this thesis, we combined chaos elementary theories with spread spectrum communication theories, and placed emphasis on researching discrete chaotic sequences, spatiotemporal chaotic sequences and the system performance in spread spectrum communication. The main researches and innovations are given:1. We described the definition of chaos, the essence and the basic characteristic. We can know the chaotic behavior from the perception by analyzing several classic chaotic systems. Besides this, we also have qualitatively studied the chaotic systems'properties, and the judgment methods to measure the state of chaos.2. The properties of chaotic sequences relate to the address choice of spread spectrum communication. This thesis has studied the chaotic sequences in detail and has carried on the analysis to several kinds of common chaotic sequences'statistical properties, such as banlance, run-length distribution, and so on. Especially, we used approximate entropy algorithm not the Berlekamp-Massey algorithm to analyze the complexity of sequences. The experimental simulation results have proven the feasibility and the superiority of chaotic sequences to replace tradition spread spectrum sequences.3. We proposed the way to generate spatiotemporal chaotic sequences based on the two-dimensional coupled map lattices. And it gives a detail study about spatiotemporal chaotic sequences in the paper. The simulation results show that spatiotemporal chaotic sequences provide some good performance sequences for the spread spectrum communication system.4. We utilized the chaotic sequences in the spread spectrum sequences communication system. Under the wireless environments, we compared the simulation results in different parameters. The simulation experiments show that the performance of chaotic sequences is better than that of traditional spread spectrum sequences, which provides important sense and value for the performance of spread spectrum communication.