Performance analysis of UAV-assisted DF relaying network with hardware impairments and energy harvesting

The unmanned aerial vehicle (UAV) is considered a promising auxiliary relay for enhancing network coverage due to its easy deployment, agility, and maneuverability. In order to overcome the obstruction of towering buildings and the limitation of relaying energy, this paper proposes a half-duplex decode-and-forward UAV-assisted relaying network based on simultaneous wireless information and power transfer scheme. The power splitting (PS) is implemented at the UAV relay to address the challenge of energy limitation by separating information and energy from the radio frequency signal. We also study the impact of hardware impairments on transmitters, which can actually degrade communication performance. We derive both an exact expression and asymptotic analysis for the outage probability (OP) with energy harvesting and hardware impairments. In addition, we formulate an optimization form to find the optimal PS ratio and minimize the outage probability. Due to the nonconvex nature of this optimization problem, we perform a series of transformations to reformulate it into a convex optimization form. Experimental simulations validate our theoretical results. Specifically, optimal altitude for UAV is about 300 m and relatively constant in different conditions. The OP of our work is nearly 0.33 smaller than that of AF relaying in a given situation. Moreover, we provide practical guidance for the design and deployment of the UAV-assisted communication by exploring the effects of UAV’s altitude, hardware impairments level, and power splitting ratio on the outage probability.