Two-Way Cooperative Cognitive Radio Networks with Nonlinear RF-Energy Harvester

In this paper, we consider simultaneous wireless information-and-power transfer (SWIPT) for a cooperative cognitive radio network (CRN). Herein, one secondary user (SU) among a preselected pair of SUs provides relay assistance to realize communications between two primary users (PUs). In exchange for this cooperation, SUs can harvest energy from the radio-frequency (RF) signals of the PUs and enable their communications in the same license band. With the considered set-up, three phases are required to perform two-way end-to-end communications between the PUs and one-way communication between SUs. For making use of RF energy harvesting, a power splitting based receiver architecture is considered at the relaying SU. Moreover, the relaying SU follows an amplify-and-forward approach to broadcast the combined signals of PUs and SU. For performance analysis, we derive accurate expressions of the outage probability (OP) for the secondary system under Nakagami- m fading by adopting a nonlinear energy harvester at the relaying SU. Further, we formulate achievable throughput of the secondary system. To validate the derived analytical framework and show the impact of different system parameters, analytical and simulation results are provided.