Dissertation
Dissertation > Industrial Technology > Radio electronics, telecommunications technology > Communicate > Confidentiality of communications and communications security > Password, machine

Secure Chaotic Sequence Modulation Based on Spatiotemporal Chaos Synchronization

Author YangJianRen
Tutor XiaoJingHua
School Beijing University of Posts and Telecommunications
Course Physical Electronics
Keywords Chaos Synchronization Coupled Map Lattice Entropy Method Demodulation Chaotic Spread-spectrum Modulation
CLC TN918.2
Type Master's thesis
Year 2010
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In recent years, the application of chaos in communication has got more and more attention. Since Pecora and Carroll proposed chaos synchronization method in the last century, people have designed a variety of chaotic communication schemes. In the chaotic communication systems, the chaotic modulation scheme is an extremely important aspect, a modulation technique that has excellent performance can reduce the communication error rate, and improve communication effectiveness greatly. Traditional chaotic modulation techniques are generally based on one-dimensional chaotic systems. Because the one-dimensional chaos is easy to be restored, traditional modulation techniques have a bad security. Therefore, the attention of chaotic communication research is gradually shifted from the simple chaotic dynamical systems to the complex spatiotemporal chaotic dynamical systems. But the spatiotemporal chaos systems have a high degree of spatial and temporal complexity, so a model named Coupled Map Lattice has been introduced to simplify the difficulty of spatiotemporal chaos Analysis. This model can not only render extremely rich spatiotemporal behavior of chaotic dynamics, but also easy to implemented, so we choose it as the spatiotemporal chaos model in this paper.To study the intrinsic features of spatiotemporal chaotic systems deeply, an information entropy research method has been introduced. Because the using of information entropy method in spatiotemporal chaos system research is very simple and effective, so this paper use this method to discuss some internal features of spatiotemporal chaotic systems in detail, and give a quantitative description for the relationship between its internal nodes. On the basis of the quantitative analysis, this paper designs a chaotic sequence modulation communication model based on spatiotemporal chaos synchronization, and introduces a demodulation scheme that can restore the original information using the coupling degree of chaotic sequences, and achieve the simulation of its communication process.In addition, because the spatiotemporal chaos can not only generate a large number of time sequences that have excellent relevant feature, but also can realize fast synchronization driven by the signal of a node. So it can be used to generate a large number of chaotic spreading sequences in chaotic spread spectrum communication systems. At present, some academics have already designed a multi-user spread spectrum communication system based on one signal driven spatiotemporal chaos synchronization, but due to the constraints of the inherent coupling between the spatiotemporal nodes, this system can only achieve communications between two identified locations. So it doesn’t meet the mobility requirement of contemporary communication. In order to improve its shortcoming, this paper presents a concept of tabbing sequence, and designs a more practical multi-user spread-spectrum access system based on spatiotemporal chaos synchronization and CPSK digital modulation, and analyses its safety performance by simulating.

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