Secrecy Outage of a Cognitive Radio Network with Selection of Energy Harvesting Relay and Imperfect CSI

This paper investigates the physical layer security of an underlay cognitive radio network with relay selection scheme under threats of an eavesdropper. We consider a set of intermediate relays working in decode and forward mode. The relays harvest energy from radio frequency signal transmission of secondary user (SU) using a time switching relaying. We evaluate the secrecy outage probability (SOP) of secondary relay network assuming that the channel state information (CSI) of the interfering links from both the SU and relay transmitter to primary user (PU) receiver are imperfect. The transmit power of the SU as well as relay is controlled by the maximum tolerable interference at PU because of underlay environment and outage constraint of PU as demanded by quality of service of PU. The impact of several network parameters such as maximum tolerable interference threshold, number of relays, time for energy harvesting, imperfection in CSI and primary outage constraint on the secrecy outage of the SU network is indicated. The influence of relay selection scheme on SOP with energy harvesting and imperfect CSI is indicated.