Secrecy Performance Analysis With Optimal Df Relay Selection Of Underlay Cr Networks Over Nakagami-M Fading Channels

In this paper, the secrecy outage performance of an underlay cognitive decode-and-forward (DF) relay network over independent and non-identical distributed (i.n.i.d) Nakagami-m fading channels is investigated, in which the secondary user transmitter communicates with the secondary destination via relays, and an eavesdropper attempts to overhear the information. We assume that the channel state information (CSI) of all links is available. The exact and asymptotic closed-form expressions for the secrecy outage probability with optimal relay selection are derived, and verified by Monte-Carlo simulations. Through asymptotic analysis, we find that the secrecy diversity order is determined by the number of relays and the fading parameters between relay and destination.