The Performance Analysis Of Non-Coherent DCSK System

Chaos is an important branch of nonlinear science. The research of chaos theory and its application in communication is the frontier of science and engineering, which provides a novel research field for conventional commu- nication theory and also presents a broad application platform for nonlinear science. People used to focus mainly on modulating methods and noise performance of chaos-based communication system, but lack of multipath and anti-jamming performance analysis, which is one important performance of any communication system. Recently, Chaos shift keying system attracts much attention in chaos-based communication system. This paper focus mainly on analyzing the performance of differential chaos shift keying(DCSK)system in anti-jamming, multi-path fading and multiple access ability.Firstly, how to choose spreading factor of non-coherent DCSK system that minimizes the bit error rate for a given Eb /N 0 is discussed in this paper. Then, analytical expressions of the bit error rates are derived under Rayleigh fading model and multi-path Rayleigh fading channel model. Analytical and simulation results are compared. The multi-path performance of the non-coherent DCSK system is also compared with that of the coherent CSK system. Secondly, we analyse the anti-jamming performance of coherent CSK system and non-coherent DCSK system under a narrowband sine wave jamming, and analyse the performance of chaotic communication system under coexisting with a conventional spread spectrum communication system, such as direct-sequence spread spectrum (DS-SS) system.Finally, on the base of time-delay-based multiple access DCSK (TLMA-DCSK) system, a modified TLMA-DCSK method is proposed. Analysis performance expressions of the bit error rates are derived, and Logsitic map with zero mean is used for chaos generation in simulation. Comparing with TLMA-DCSK system, the modified TLMA-DCSK system is better than TLMA-DCSK in system performance.