Full-Duplex Cognitive Radio with RF Energy Harvesting

Abstract

With the development of self-interference suppression techniques, full-duplex (FD) communication is expected to double the spectrum efficiency (SE). In FD based cognitive radio (CR), the secondary users (SUs) can perform spectrum sensing and data transmission simultaneously, with the goal of achieving better sensing performance or higher throughput for the SUs. Another key performance metric in fifth-generation (5G) wireless networks, energy efficiency (EE), has attracted more and more attention recently. The radio frequency (RF) energy harvesting (EH) technique is proposed to prolong the battery lifetime of low-power communication devices. In this paper, we are interested in the full-duplex CR with energy harvesting. We consider that the SUs can harvest RF energy from the PU and recycle part of its own energy when the secondary data transmission is conducted. The EE of the CR system is defined as the ratio of the average SE over the average power consumption. The system parameters, including the sensing thresholds and the secondary transmit power are optimized to maximize the EE under the constraint that the primary user (PU) is sufficiently protected. Finally, the simulation results are presented to show the outperformance of the proposed FD-EH scheme.