Autonomous Sensing UAV for Accurate Multi-User Identification and Localization in Cellular Networks

This paper presents an autonomous sensing frame- work for identifying and localizing multiple users in Fifth Generation (5G) networks using an Unmanned Aerial Vehicle (UAV) that is not part of the serving access network. Unlike conventional aerial serving nodes, the proposed UAV operates passively and is dedicated solely to sensing. It captures Uplink (UL) Sounding Reference Signals (SRS), and requires virtually no coordination with the network infrastructure. A complete signal processing chain is proposed and developed, encompassing synchronization, user identification, and localization, all executed onboard UAV during flight. The system autonomously plans and adapts its mission workflow to estimate multiple user positions within a single deployment, integrating flight control with real-time sensing. Extensive simulations and a full-scale low- altitude experimental campaign validate the approach, showing localization errors below 3 m in rural field tests and below 8 m in urban simulation scenarios, while reliably identifying each user. The results confirm the feasibility of infrastructure-independent sensing UAVs as a core element of the emerging Low Altitude Economy (LAE), supporting situational awareness and rapid deployment in emergency or connectivity-limited environments.