Channel Measurements and Analysis for Fixed-Wing UAV-to-Vehicle Communications at 2.7 GHz in Rural Area

As a key potential technology of future intelligent transportation system (ITS), the unmanned aerial vehicle (UAV)-to-vehicle (U2V) communication has attracted widespread attention in recent years. The study of the U2V propagation channel characteristics is of great importance for system design and testing. However, there is still a lack of extensive research on the U2V channel with high dynamic UAV and vehicle in rural area for ITS applications. In this letter, we present a wideband U2V channel measurement campaign at 2.7 GHz with UAV altitudes from 400 m to 800 m. A comprehensive investigation on large- and small-scale fading characteristics is presented. In particular, we find that the close-in (CI) model outperforms the floating intercept (FI) model in terms of prediction performance and robustness for theoretical analysis. In addition, we propose a simple altitude-dependent decorrelation distance model for shadow fading. The observed K-factor under line-of-sight (LOS) condition is statistically higher than non-line-of-sight (NLOS) condition with nonlinear dependency on UAV altitude. These findings help to design and optimize the U2V communication system for the future ITS.