Measurement-Based Modeling and Analysis of UAV Air-Ground Channels at 1 and 4 GHz
Existing vertical-dimension channel models for unmanned aerial vehicle (UAV) air-to-ground communications suffer from insufficient accuracy, particularly in characterizing height-dependent propagation effects. Method: This study conducts extensive field measurements at 1 GHz and 4 GHz across line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios, systematically quantifying large-scale path loss, shadow fading (modeled via log-normal distribution), and small-scale fading (validated against Rayleigh and Rician distributions). Contribution/Results: We propose, for the first time, a height-dependent path loss model that explicitly incorporates UAV flight altitude as a key parameter, and jointly characterize vertical-direction propagation specificity and fading statistics. The resulting high-fidelity air-to-ground channel model significantly improves link budget prediction accuracy and coverage performance assessment reliability. It provides a reproducible, scalable empirical foundation and modeling paradigm for low-altitude communication network design and optimization.