Secure Cognitive Relay Network: Joint the Impact of Imperfect Spectrum Sensing and Outdated Feedback

Abstract

In this paper, we consider cognitive relay networks with Nth best relay and beamforming schemes under the joint impact of imperfect spectrum sensing and outdated channel feedback. Specifically, we examine the secrecy performance by deriving the exact and asymptotic analytical expressions for the secrecy outage probability. Based on the analysis, we observe that these two types of channel impairments, i.e., imperfect spectrum sensing and outdated channel feedback, greatly affect the system performance. Particularly, the outdated channel feedback (i.e., the outdated coefficient $$\rho\,<\,1$$?<1) reduces the secrecy outage diversity gain of the two schemes, i.e., Nth best relay and beamforming, to one regardless of the number of relays. Our proposed analysis provides a helpful guideline for security system designers to cope with the unpleasant channel impairments.