A New Shadowed Double-Scattering Model with Application to UAV-to-Ground Communications

Double-scattering propagation models have been applied in various wireless communication environments, including vehicle-to-vehicle communications and cooperative amplify-and-forward relaying. In all these scenarios, when obstacles exist between the transmitter (Tx) and the receiver (Rx), the average received power varies in a random manner, resulting to the shadowing effect. The combination of double-scattering and shadowing represents a composite fading scenario, which models worse than Rayleigh fading conditions. In this paper, we propose a new shadowed double-scattering distribution that can model various fading and shadowing conditions. To this aim, the inverse-gamma (IG) distribution is employed for modeling the shadowing coefficient and the Nakagami- $m$ for the multipath fading. For the resulting double-Nakagami-IG distribution, an analytical stochastic framework has been developed for presenting important statistical properties. Moreover, the theoretical results have been compared with empirical ones, based on a measurement campaign that has been performed in an unmanned aerial vehicle (UAV)-to-ground communication scenario. It is shown that the proposed new distribution can efficiently model such communication environments, since it provides a notable fit to the empirical data.