SECURE PERFORMANCE ANALYSIS OF BUFFER-AIDED COGNITIVE RELAY NETWORKS UNDER DELAY UNCONSTRAINT CASE

This paper investigates the physical layer security for a buffer-aided cooperative cognitive radio network in the presence of an eavesdropper, wherein the relay is equipped with a buffer so that it can store packets received from secondary source. Multiple primary users (PUs) locate in the transmission range of the secondary users (SUs), and quality of service (QoS) requirement of them must be guaranteed. To improve the secure performance of cognitive radio networks, we propose a novel secure link selection scheme which incorporates the instantaneous strength of the wireless links and the status of buffer, the interference on PUs should be kept below a specific threshold simultaneously. Closed-form expressions of secrecy outage probability (SOP) for cognitive radio network is obtained based on the Markov chain. Numerical results demonstrate that the proposed scheme can significantly enhance the secure performance compared to the conventional relay selection scheme.