Propagation Measurements and Modeling for Low Altitude UAVs From 1 to 24 GHz

TL;DR

This paper presents a new propagation model for low altitude UAV communications across 1 to 24 GHz, accounting for NLoS conditions in suburban environments, based on extensive measurements.

Contribution

It introduces a comprehensive NLoS propagation model for UAVs at multiple frequencies, incorporating diffraction and multipath effects validated by real-world measurements.

Findings

Model accurately predicts excess path loss in NLoS conditions.

Diffraction dominates below 4 GHz, multipath above 4 GHz.

Measurements confirm the model's applicability in suburban environments.

Abstract

In most countries, small (<2 kg) and medium (<25 kg) size unmanned aerial vehicles (UAVs) must fly at low altitude, below 120 m, and with permanent radio communications with ground for control and telemetry. These communications links can be provided using 4G/5G networks or dedicated links, but in either this case the communications can be significantly degraded by frequent Non Line of Sight (NLoS) propagation. In this case, reflection and diffraction from ground objects are critical to maintain links, and hence accurate propagation models for this must be considered. In this letter we present a model for path loss when the UAV is flying in NLOS conditions. The study is based on measurements made at frequencies of 1, 4, 12, and 24 GHz with a UAV flying in a suburban environment. Measurements have been used to model NLOS propagation below 4 GHz, where the dominant mechanism is diffraction, and above 4GHzwhere multipath is the dominant propagationmechanism. The model can be of use in predicting excess losses when UAVs fly in suburban NLOS conditions.