Energy-Efficient UAV Multicasting with Simultaneous FSO Backhaul and Power Transfer

TL;DR

This paper proposes an energy-efficient UAV multicasting system that leverages simultaneous FSO backhaul and power transfer, optimizing system parameters to maximize energy efficiency while ensuring sustainable operation and reliable backhauling.

Contribution

It introduces a novel UAV multicasting framework with simultaneous FSO backhaul and power transfer, including joint design and low-complexity suboptimal solutions.

Findings

Achieves near-optimal energy efficiency through joint FSO and RF link optimization.

Demonstrates the effectiveness of power-rate tradeoff balancing in system performance.

Provides analytical derivation of UAV multicast rate under PPP-based user distribution.

Abstract

This letter studies an unmanned aerial vehicle (UAV) aided multicasting (MC) system, which is enabled by simultaneous free space optics (FSO) backhaul and power transfer. The UAV applies the power-splitting technique to harvest wireless power and decode backhaul information simultaneously over the FSO link, while at the same time using the harvested power to multicast the backhauled information over the radio frequency (RF) links to multiple ground users (GUs). We derive the UAV's achievable MC rate under the Poisson point process (PPP) based GU distribution. By jointly designing the FSO and RF links and the UAV altitude, we maximize the system-level energy efficiency (EE), which can be equivalently expressed as the ratio of the UAV's MC rate over the optics base station (OBS) transmit power, subject to the UAV's sustainable operation and reliable backhauling constraints. Due to the non-convexity of this problem, we propose suboptimal solutions with low complexity. Numerical results show the close-to-optimal EE performance by properly balancing the power-rate tradeoff between the FSO power and the MC data transmissions.