Optimal UAV-Aided RFET System Design in Presence of Hovering Inaccuracy

Abstract

In this paper, performance of unmanned aerial vehicle (UAV)-aided RF energy transfer (RFET) in presence of hovering inaccuracy is investigated. Hovering inaccuracy of UAV comprises of two types of mismatches: Localization mismatch (LM) and Orientation mismatch (OM) . Thus, a total of four combinations arise. Their impact on received power at ground deployed sensor node is characterized. For this purpose, a generalized radiation pattern of UAV-mounted transmitter antenna is considered. A closed-form expression of received power at the sensor node is obtained for each of these four cases. An optimization problem is formulated with the objective of optimizing the system parameters, such as transmit power, hovering altitude, and antenna exponent. This problem contains mixed nature of variables, i.e., continuous as well as discrete. To solve this problem, an algorithm, called Hovering Inaccuracy-aware Optimal Charging System Design (HI-OCSD) , is proposed to find the optimal system parameters. Through system simulations it is demonstrated that, hovering inaccuracy has notable impact on the performance, as received power at the sensor node reduces significantly in presence of hovering inaccuracy compared to ideal scenario. The effect of LM is more severe than that of OM . Further, a scenario with different level of hovering inaccuracy accounting for different deployment scenarios is considered, and the optimal system parameters are also evaluated. This study reveals that, UAV needs to hover at a relatively higher altitude to overcome the severity of hovering inaccuracy.