Chaos-Based Physical Layer Security in NOMA Networks over Rician Fading Channels

Owing to its striking features, non-orthogonal multiple access (NOMA) is considered as a key technique to realize the main goals of 5G and beyond like high reliability and user connectivity. Nevertheless, the increased number of NOMA users will degrade the privacy of users' data. On the other hand, different chaotic communication schemes have been developed to offer cost-effective physical layer security (PLS) approaches. In this paper, a generalized chaos-based secure power-domain NOMA (SPD-NOMA) is presented for the uplink large scale and Rician channels with efficient dynamic power control for the transmitted multi-level chaos-shift-keying (MCSK) signals. Integrated receiver design based on the successive interference cancellation (SIC) and chaos demodulation is proposed for multiuser detection. Numerical results verify the effectiveness of the designed SPD-NOMA scheme in terms of the achieved bit error rate, security gap, and user connectivity compared with the benchmark paradigms. Furthermore, a massive key-space is achieved to boost the system's security against the most powerful brute-force attacks.