Design and Validation of a Low-Cost 5G UAV-SDR Narrowband Channel Sounding System

This paper presents the design and experimental validation of a low-cost UAV-based narrowband channel sounding system using a Software-Defined Radio (SDR). The platform integrates RF signal acquisition with Global Navigation Satellite System (GNSS) positioning and Inertial Measurement Unit (IMU) data, enabling synchronized Received Signal Strength Indicator (RSSI) measurements and antenna orientation estimation at 3.5 GHz. Experimental results validate the proposed multi-sensor architecture and demonstrate its suitability for orientation dependent air-to-ground channel characterization. Moreover, the measured RSSI exhibits good agreement with the Free-Space Path Loss and Two-Ray propagation models, confirming the reliability and flexibility of the proposed platform for air-to-ground propagation measurements.