Physical Layer Security with Non-Linear Energy Harvesting Relay

In this paper, we studied the performance of an underlay cognitive radio network (CRN) with an energy harvesting (EH) relay in terms of physical layer security. The relay is considered to follow a non-linear EH model for harvesting energy from the RF signal of the secondary user (SU) using a time switching relay (TSR) scheme. We assumed the non-linear energy harvesting model as it is more realistic compared to linear energy harvesting. Further, we considered the CSI of the interfering link is imperfect. The transmit power of the source, and EH relay is limited due to underlay CRN to maintain the maximum tolerable interference at the primary user (PU). The effect of EH time, maximum acceptable interference threshold, saturation threshold related to non-linear EH, imperfect CSI, and PU outage constraint on the secrecy outage of the SU network is also investigated. Impact of non-linear EH on SOP is compared with that of linear EH.