Air-Ground Channel Characterization for Unmanned Aircraft Systems: The Hilly Suburban Environment

We provide measurement results from an air-to-ground channel measurement campaign undertaken in a hilly terrain suburban environment. This campaign is part of a larger project-sponsored by NASA-aimed at developing measurement based models for the air-to-ground channel, for use in evaluation of unmanned aircraft system (UAS) communication link development. Our measurements provide dual-band SIMO power delay profiles, from which we compute propagation path loss, root-mean square delay spread, and correlations among the two bands. The two signal frequencies are 968 MHz and 5060 MHz. For this hilly environment, average propagation path loss follows the curved-earth two-ray model, with reduced variation about this model attributable to multiple weaker reflections and scattering from the hilly terrain and buildings. Root-mean square delay spreads vary, with the majority of values 10-20 ns, but occasional larger values of nearly 1000 ns. As expected, the line of sight signal components in the two bands are essentially uncorrelated, but correlations for the signal components on the two antennas in the same band vary depending upon flight path geometry.