Secrecy performance of a generalized partial relay selection protocol in underlay cognitive networks

Summary In this, we propose a generalized partial relay selection (PRS) protocol to enhance the secrecy performance for cooperative cognitive radio networks (CRNs) in terms of the secrecy outage probability (SOP) and the probability of non‐zero secrecy capacity (NSC). In the proposed scheme, a secondary source communicates with a secondary destination via the assistance of multiple secondary relays, in the presence of multiple secondary eavesdroppers and multiple primary users (PUs). With a reliance on the source‐relay channel state information (CSI), the source selects a group of the potential relays, and one is then chosen to forward the source data to the secondary destination using the randomize‐and‐forward (RF) technique. We consider the relay selection methods in two practical cases, where the CSIs of the eavesdropping links are available or not available. For the performance evaluation and comparison, we derived exact and asymptotic SOP and NSC closed‐form expressions for the proposed protocols and the corresponding full relay selection (FRS) protocol over Rayleigh‐fading channels. Finally, Monte Carlo simulations are presented to confirm the theoretical‐derivation correction. The results confirmed that the proposed protocols can outperform the conventional PRS protocols by designing the number of the potential relays appropriately. We propose a generalized partial relay selection (PRS) protocol to enhance the secrecy performance for cooperative cognitive radio networks (CRNs) in terms of the secrecy outage probability (SOP) and the probability of non‐zero secrecy capacity (NSC).