Air-ground channels & models: Comprehensive review and considerations for unmanned aircraft systems

Use of unmanned aircraft systems (UASs) for multiple applications is expected to grow dramatically in the coming decades; this fact has motivated this paper's focus on fundamental physical layer characteristics relevant to UAS communications. In the past, for aeronautical communications with high transmitted power levels, narrow signal bandwidths, elevated ground site antennas in open areas, and low duty cycle transmissions, simple models for...