Physical layer security for dual-hop SWIPT-enabled CR networks

We investigate the physical layer security of a relayassisted underlay cognitive radio network with simultaneous wireless information and power transfer (SWIPT). To this end, we consider a secondary network comprising a secondary source S, one secondary user (SU) relay R, one SU destination D, one primary user (PU) transmitter, and one PU receiver. In addition, we consider an eavesdropper E which can overhear both communications of the S→R and R→D links whereas power constraints are imposed on the secondary network in order to maintain a tolerable interference level at the primary network. Under these constraints, we derive a closed-form expression for the secrecy outage probability assuming uncorrelated Rayleigh fading channels. Numerical and simulation results are presented to corroborate the corresponding analysis. It is shown that the harvested energy, energy conversion efficiency, and maximum tolerable interference level imposed on the primary receiver impact considerably the overall system's security.