Physical Layer Security of Overlay Cognitive NOMA Systems with Control-Jamming

In this paper, we investigate the physical layer security (PLS) of an overlay cognitive non-orthogonal multiple access (NOMA) system with control-jamming (CJ) under Nakagami-m fading. Herein, a cooperative decode-and-forward (DF) relaying technique is adopted at the secondary transmitter, while a maximal ratio combining (MRC) scheme is employed at the primary destination in order to improve the secrecy performance of the underlying system. Under this setup, we derive analytical expressions for the secrecy outage probability (SOP) and the strictly positive secrecy capacity (SPSC). Moreover, we obtain simple and explicit expressions of the SOP in the high signal-to-noise ratio (SNR) region to get useful insights on the system design for both the cases of without and with jamming. Finally, Monte Carlo simulations are provided to: (i) demonstrate the effectiveness and superiority of the proposed system with jamming over its non-jamming counterpart in terms of security; (ii) verify the accuracy of the proposed analytical framework.