A UAV-aided channel sounder for air-to-ground channel measurements

Unmanned aerial vehicle (UAV) is a promising platform for future communication systems due to its high mobility, maneuverability, and low cost. The unique features that distinguish UAV communications from conventional land communications include the high altitude, mobility, and three dimensional (3D) trajectories. Thus, it is urgent to measure and analyze the characteristics of air-to-ground (A2G) channels. In this paper, a UAV-aided channel sounder for characterizing A2G channels is developed, which includes two components, i.e., the air transmitter and ground receiver. For measuring the channels, the raw channel impulse response (CIR) is extracted from the measured channel data firstly. According to the parametric channel model, the simplified and more practical CIR is then reconstructed by the clustering and parameter estimation algorithms. In order to verify the effectiveness and accuracy of proposed channel sounder, a commercial channel emulator is used to reproduce realistic channels in the lab and calibrate the measured results by the proposed channel sounder. Finally, the channel sounder is applied to measure the air-to-ground channels under campus scenarios, which shows that the measured channel parameters such as path loss and path delay are consistent with the theoretical ones.