Wireless powered cognitive radio networks with multiple antenna sources and hardware impairments

Abstract

In this paper, a radio-frequency (RF) energy harvesting enabled cognitive radio network (CRN) is considered in the presence of transceiver hardware impairments (HIs). Herein, one of the secondary nodes (SNs) exploits simultaneous wireless information and power transfer (SWIPT) technology to harvest energy from the primary signal and provides relay assistance for the primary transmission. We consider multiple antennas at the primary nodes (PNs) to ensure better link reliability and spectrum sharing to mitigate the spectrum scarcity. In the first phase, relaying SN uses non-linear energy harvester circuit to harvest energy from the RF signals received from PN using the power splitting approach. In the second phase, the same SN adds its own signal intended for the other SN along with the primary signal and broadcasts the combined signal. Assuming the network to operate in a Nakagami- fading environment, the performance of the considered CRN is evaluated in terms of outage probability and system throughput. Also, we formulate two optimization problems to minimize the OP and maximize the system throughput. The Karush–Kuhn–Tucker conditions are used to obtain the closed-form solution of the constrained convex optimization. Numerical results are provided to examine the performance impact concerning different system and channel parameters.