On Outage Secrecy Minimization using Jammer Selection in Energy Harvesting Cognitive Radio

Abstract

This work considers a cognitive radio network (CRN) model that consists of a secondary transmitter-receiver pair and operates in an underlay mode on two non-overlapping time slots in presence of an eavesdropper ( $E_{av}$ ) and multiple cooperative jammers. In the first time slot, the secondary transmitter ( $SU_{\mathcal{T}}$ ) and the jammers harvest energy from the interference signal of the primary user (PU). During the remaining slot, $SU_{\mathcal{T}}$ transmits its data to its receiver maintaining a target interference threshold to the primary receiver ( $PU_{\mathcal{R}}$ ). The jammer with the minimum signal-to-interference ratio at $E_{av}$ is selected to countermeasure eavesdropping. Closed form expressions for the total power budget, the optimal power fraction used by $SU_{\mathcal{T}}$ and the fraction of the time slot for energy harvesting are derived to minimize the secrecy outage probability under the constraints of secondary outage probability, interference to $PU_{\mathcal{R}}$ and energy causality for both $SU_{\mathcal{T}}$ and the jammers. Simulation results show that the minimum value of the secrecy outage probability is ∼ 18.69% less for the proposed method compared to the existing work.