Discrete Chaotic System Based Digital Communications System Design

Chaotic signals, generated by a deterministic nonlinear system, not only have initial value sensitivity, continuous bandwidth power spectrum but also have non-periodic and highly irrelevant features, which are widely used in digital communication system especially secure communication systems. So the research on chaotic digital communications has broad application prospect and significance. Based on the existing research, in order to overcome the drawbacks of differential chaotic shift keying (DCSK) and correlation delay shift keying (CDSK), considering the autocorrelation of discrete chaotic signal, a novel chaotic communication method is proposed. The dissertations mainly include the following aspects:Firstly, an overview of fundamentals and applications of chaotic systems is given. The historical motivation of the use of chaos in this context is introduced. Recent advances and future challenging problems are surveyed.Secondly, based on the analysis of DCSK, the performance analysis of DCPSK in AWGN channels, Rayleigh channels and Rician channels is well discussed. Computer simulations are given to verify its preferable noise and multipath fading immunity to DCSK.Thirdly, based on the analysis of DCPSK and CDSK, a novel chaotic communication method is proposed using chaos--Segment Shift Correlation Delay Shift Keying (SSCDSK). As a multilevel modulation scheme, the principles of its modulation and demodulation are elaborated. Simulations of 4-ary SSCDSK and 2-ary SSCDSK are given to verify its preferable noise immunity.