# Energy Efficiency Optimization for UAV-assisted Backscatter Communications

## TL;DR

This paper proposes an energy-efficient UAV-assisted backscatter communication system for IoT, optimizing UAV location to balance outage probability and energy use, with analytical and simulation validation.

## Contribution

It introduces a novel UAV-assisted backscatter communication framework with an optimization method for UAV placement to maximize energy efficiency under energy constraints.

## Key findings

- Optimal UAV location is closer to tags for lower UAV transmit power.
- Trade-off exists between UAV data collection position and outage probability.
- Analytical and simulation results confirm the effectiveness of the proposed optimization.

## Abstract

Future Internet-of-Things (IoT) has high demand for energy-saving communications, especially in remote areas and smart cities. To meet this demand, we propose novel Unmanned Aerial Vehicle-assisted backscatter communications, where a UAV first collects data from multiple terrestrial backscattering tags via time division multiple access, and then flies into the coverage region of a terrestrial base station to upload its collected data to its associated base station. To determine the optimal UAV data collection location, we first analyze the system average outage probability, and then optimize the energy efficiency with the optimal backscattering location through Golden Section method under UAV energy constraint. Our analytical and simulation results illustrate that there is a trade-off between UAV data collection location and the outage probability, and the optimal UAV data collection location to achieve maximum energy efficiency needs to be closer to the tags for lower UAV transmit power.