Performance analysis of downlink NOMA–EH relaying network in the presence of residual transmit RF hardware impairments

Abstract

In this paper, we investigate the effects of residual-transmit radio-frequency impairments on the downlink non-orthogonal multiple access system with perfect successive interference cancellation using an energy-harvesting (EH) relay in which nodes in the network are equipped with a single antenna. The source node communicates with two users with the help of the amplify-and-forward EH relay node. In addition, both the power-splitting relaying (PSR) and time-switching relaying (TSR) protocols are examined. To evaluate the performance of the proposed system, closed-form expressions of the outage performance and the available throughput are derived over Rayleigh fading channels. Moreover, the accuracy of analytical results is verified by a Monte Carlo simulation. The results show the effects of various parameters, such as power allocation factors, the relay node location, data rate, transmit hardware impairment level, and power allocation factors on the outage performance ($${\mathcal {OP}}$$) and throughput with two users for both PSR and TSR architectures in the presence of hardware impairments. Furthermore, these results are compared with performance of orthogonal multiple access (OMA) EH relaying system.