  Unmanned aerial vehicle (UAV)-enabled communications have been proposed as a
critical part of the beyond fifth-generation (5G) cellular networks. This type
of communications is frequently characterized by line-of-sight (LoS) and
dynamic propagation conditions. However, in various scenarios, the presence of
large obstacles in the LoS path is unavoidable, resulting in shadowed fading
environments. In this paper, a new channel model is proposed, in which the
effects of mobility and shadowing are simultaneously considered. In particular,
the performance of a UAV-based communication system operating in a shadowed
double-scattering channel is analyzed. {The new channel model is generic, since
it models various fading/shadowing conditions, while it is in terms of
easy-to-evaluate mathematical functions. Moreover, a low complexity UAV
selection policy is proposed, which exploits shadowing-related information. The
proposed scheme offers a reduction of the signal processing complexity, without
any important degradation on the performance, as compared to alternatives
approaches.} In this context, a new analytical framework has been developed for
investigating the performance of the new strategy. Finally, the main outcomes
of this paper are also validated by empirical data, collected in an
air-to-ground measurement campaign.
