Measurements and Modeling of Radiohelmet-UAV LoRa Links in a Mountain Canyon

The LoRa framework has been recently proposed to foster search and rescue (SaR) missions in mountain environments. The target to be rescued could wear a LoRa radio embedded in a safety helmet so that an unmanned aerial vehicle (UAV) can localize it based on the transmitted signal strength. However, radiohelmet-to-UAV links in a real mountain area have never been characterized. This paper reports measurements of the excessive aerial path loss (PL) seen by a UAV overflying a mountain canyon to derive an equivalent model with the final aim of applying signal-strength-based localization. The angle-dependent fitting well describes the excessive aerial PL, and, despite the iced canyon's walls, no significant seasonal difference in the PL is experienced.