Paper #3

CSK Modulation for Secure Wireless Communication Networks

Rana H. A. Zubo, Walid A. Al-Hussaibi and Raed Abd-Alhameed

Abstract: Physical layer security (PLS) has been considered as a key technology to fulfill the information confidentiality request of modern and future communication networks. Therefore, diverse chaos-based wireless communication (CBWC) systems have been developed as low complexity and cost-effective PLS approaches when compared with the upper layer secrecy protocols. In particular, chaos-shift-keying (CSK) modulation schemes have attracted significant research efforts owing to the simple signal generation techniques and enhanced secrecy. However, the practical implementation of CSK for secure data transmission over realistic CBWC channels still needs further investigation. In this paper, the application of CSK based on multiple chaotic basis functions is examined over a band-limited CBWC channel with Rayleigh fading process. Lorenz and Chua chaotic oscillator circuits are used as basis signal functions for CSK modulation at the transmit side and chaos demodulation/synchronization at the receiver end. The impact of channel bandwidth and requisites of the front-end receiver is modeled as a low pass filter process. Performance results show that chaos filtering can greatly affects the physical features of employed signals at different levels. The achieved results confirmed that inadequate filter bandwidth can remarkably distort the state-space, signature waveform, and spectral components of CSK signals in disparate extents regardless of high SNR level. For target error rate and worst-case eavesdropping secrecy, this issue has a direct impact on decreasing the error security gap of CBWC system compared with the reference CSK schemes based on a single chaotic base function, even at a high received signal-to-noise ratio. As a feasible solution to mitigate the degradation in system reliability and secrecy, it is demonstrated that the designed filter bandwidth must include the effective spectral components of utilized chaotic signals.

Keywords: Chaotic circuits; chaotic communications; CSK; error security gap; physical layer security; wireless channels.