Spread Spectrum Communication System Research Based On Chaotic Sequence

In the information age, how to ensure the security and effectivity and reliablity of communication as much as possible is a major issue that people need to be resolved. At the same time, with accelerating the deployment of LTE networks and the popularity of 3G network services, the number of global mobile users has been into the explosive growth period, so valuable spectrum resources become increasingly strained. Spread spectrum communication technology has become the more obvious advantages of communication. It is an effective wireless transmission for jamming communications technology.Performance merits of spread spectrum communication system depend largely on the performance of the selected spreading sequence, which has a good pseudo randomness and correlation that are essential for spread spectrum communication system.Traditional pseudo-random sequence such as m-sequence, Gold sequence etc, the limited number of the sequence is difficult to meet the requirements of large-capacity system, and they provide limited confidentiality, are readily be deciphered, also, the correlation is not ideal. The application of chaotic sequence in spread spectrum communication system provides a good solution. Chaotic sequences have the characteristics of broadband, like noise, difficult to predict, and is very sensitive to initial conditions. Applying Chaos theory to spread spectrum communication technology has become a hot research topic. This paper focuses on the chaotic sequence spread spectrum and its application in direct spread spectrum communication system to do a thorough research.This paper explores the chaos theory and spread spectrum communication theory in depth,analyzed chaotic sequence generated by Logistic map, Tent map, Chebyshev map and Hybrid map on initial value sensitivity, autocorrelation, cross-correlation and balance, also the relationship between the main parameters in detail, providing a theoretical basis for the design of the new chaotic system.Then, for the defection of single-level chaos mapping, this paper proposes a new chaotic sequence scheme based on Hybrid map and Chebyshev map, giving the specific design of the framework and method of generation. At the same time, this paper proposes a new chaotic quantization scheme, and analysis the initial value sensitivity, correlation and balance of the new chaotic sequence in detail, obtaining the performance advantages of the new chaotic spreading sequence. At the same time, this paper also improve and achieve an optimization scheme to chaotic sequence, giving optimization performance indicator to optimize chaotic spreading sequence, and comparing with single-level Chebyshev chaotic map and Hybrid map. The simulation results show that the number of available chaotic sequences designed in this paper has obvious advantages.Finally, we focus on the direct sequence spread spectrum communication system, carried out a detailed analysis of its anti-interference ability. In order to visually analyze the transmission characteristics in chaotic sequence in the system, using Matlab/Simlink software simulation platform for the various modules of the system simulation analysis,giving the overall system simulation models. Comparing with other single-level chaotic map sequence, the results show that the error rate is reduced. Therefore, the new chaotic spreading sequences have good anti-jamming capability.