Line-of-Sight Probability for Outdoor-to-Indoor UAV-Assisted Emergency Networks

TL;DR

This paper models the likelihood of establishing Line-of-Sight links in UAV-assisted emergency networks, aiding optimal UAV placement and network performance in urban outdoor-to-indoor scenarios.

Contribution

It introduces a closed-form expression for LoS probability considering UAV position, building size, and window size, enhancing understanding of UAV-assisted emergency communication links.

Findings

Derived a closed-form LoS probability expression.

Provided coverage probability analysis for UAV-assisted links.

Facilitated optimal UAV placement for emergency networks.

Abstract

For emergency response scenarios like firefighting in urban environments, there is a need to both localize emergency responders inside the building and also support a high bandwidth communication link between the responders and a command-and-control center. The emergency networks for such scenarios can be established with the quick deployment of Unmanned Aerial Vehicles (UAVs). Further, the 3D mobility of UAVs can be leveraged to improve the quality of the wireless link by maneuvering them into advantageous locations. This has motivated recent propagation measurement campaigns to study low-altitude air-to-ground channels in both 5G-sub6 GHz and 5G-mmWave bands. In this paper, we develop a model for the link in a UAV-assisted emergency location and/or communication system. Specifically, given the importance of Line-of-Sight (LoS) links in localization as well as mmWave communication, we derive a closed-form expression for the LoS probability. This probability is parameterized by the UAV base station location, the size of the building, and the size of the window that offers the best propagation path. An expression for coverage probability is also derived. The LoS probability and coverage probabilities derived in this paper can be used to analyze the outdoor UAV-to-indoor propagation environment to determine optimal UAV positioning and the number of UAVs needed to achieve the desired performance of the emergency network.