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Performance analysis of physical layer security of chaos-based modulation schemes

Chaos-shift-keying (CSK) and differential CSK (DCSK) are the two popular coherent and non-coherent modulation schemes for ultra wide-band (UWB) communications. However, security of these schemes has never been studied formally from the information-theoretic perspective. In this paper, we investigate the physical layer security of CSK and DCSK modulation schemes over AWGN and Rayleigh fading channels from the information-theoretic manner. For this aim, the average secrecy capacity and outage probability are computed and analyzed by considering the variation of bit energy Eb coming from the use of chaotic signal to convey information. Our results show that CSK has better or close secrecy capacity and outage probability compared with DCSK and the conventional spread-spectrum modulation. Additionally, these metrics favor Rayleigh fading channels over AWGN channels. Finally, we conclude that the non-constant bit energy is useful to enhance the physical layer security.