On the spatial characterization of 3-D air-to-ground radio communication channels

A three dimensional (3-D) geometric channel model is proposed for air-to-ground (A2G) communication environments. The proposed model considers air station (AS) and ground base station (BS) located at foci points of a virtual bounding ellipsoid corresponded from the delay of longest propagation path. The scattering region around the ground BS is thus designed based on this virtual bounding ellipsoid truncated by the ground plane and average rooftop level of the BS´s surroundings. Closed-form expressions for joint and marginal probability density functions (PDFs) of angle of arrival (AoA) observed at both AS and BS in correspondence with both azimuth and elevation planes are derived. Impact of various physical channel parameters on the elevational and azimuthal angular dispersion is thoroughly observed; which is useful in designing advanced signal processing techniques for directional antennas employed in aeronautical communication links. To establish the model´s validity, the obtained analytical results are compared with simulation results. For 10⁵ uniformly distributed scattering points, the best matching is observed between simulation and analytical results.