Empirical Low-Altitude Air-to-Ground Spatial Channel Characterization for Cellular Networks Connectivity

TL;DR

This paper presents an empirical study of low-altitude air-to-ground channels for cellular networks using extensive measurements across different environments and heights, providing insights into multipath characteristics for UAV communication.

Contribution

It introduces a measurement campaign and analysis methodology for A2G channels, revealing spatial and cluster characteristics across diverse scenarios and altitudes.

Findings

Multipath components vary significantly with environment and height.

Clusters of multipath components identified and characterized.

Spatial channel properties differ between rural, urban, and industrial scenarios.

Abstract

Cellular-connected unmanned aerial vehicles (UAVs) have recently attracted a surge of interest in both academia and industry. Understanding the air-to-ground (A2G) propagation channels is essential to enable reliable and/or high-throughput communications for UAVs and protect the ground user equipments (UEs). In this contribution, a recently conducted measurement campaign for the A2G channels is introduced. A uniform circular array (UCA) with 16 antenna elements was employed to collect the downlink signals of two different Long Term Evolution (LTE) networks, at the heights of 0-40m in three different, namely rural, urban and industrial scenarios. The channel impulse responses (CIRs) have been extracted from the received data, and the spatial/angular parameters of the multipath components in individual channels were estimated according to a high-resolution-parameter estimation (HRPE) principle. Based on the HRPE results, clusters of multipath components were further identified. Finally, comprehensive spatial channel characteristics were investigated in the composite and cluster levels at different heights in the three scenarios.