A Survey of Air‐to‐Ground Propagation Channel Modeling for Unmanned Aerial Vehicles

This chapter provides a review of various use cases for unmanned aerial vehicles (UAVs) to provide some context, and gives a brief literature review on existing efforts for modeling propagation characteristics of aerial links. It explains some of the unique propagation channel characteristics for UAV air‐to‐ground (AG) channels such as operating frequencies, scattering geometries, antenna effects, and Doppler, all in comparison with terrestrial channels. A review of some key considerations for AG channel measurements is also provided, including actual measurement frequencies, platform configurations, measurement environments, unique challenges for AG measurements, sounding waveform types for AG measurements, and the effects of elevation angle on measurement results. The chapter reviews the path loss and shadowing, delay dispersion, narrowband fading, Doppler spread, throughput and bit error rate characteristics, and the effects of different measurement environment types. It discusses AG propagation channel models, including models based on deterministic and stochastic models, their combination, and ray tracing simulations.