Outage performance of physical layer security for multi-hop underlay cognitive radio networks with imperfect channel state information

In this paper, we consider a multi-hop decode-and-forward (DF) relaying transmission in underlay cognitive radio networks. Considering the presence of an eavesdropper that overhears the transmission, we address secure communications of multi-hop wireless communications in terms of physical layer security. In addition, we take in to account the effect of imperfect channel state information (CSI) which is of importance issue in underlay cognitive radio. We analyze the secrecy outage performance of the system over Rayleigh fading channels. In particular, we derive the closed-form expression of the system secrecy outage probability. The analysis results are validated by the Monte-Carlo simulation results. The numerical results show that the imperfect CSI issue does not effect on the security issue of the transmission in underlay cognitive radio networks. On the other hand, the number of hops plays a key role in the physical layer security.