  Reconfigurable intelligent surface (RIS)-assisted unmanned areal vehicles
(UAV) communications have been identified as a key enabler of a number of
next-generation applications. However, to the best of our knowledge, there is
no generalized framework for the quantification of the throughput performance
of RIS-assisted UAV systems. Motivated by this, in this paper, we present a
comprehensive system model that accounts for the impact of multipath fading,
which is modeled by means of mixture gamma, transceiver hardware imperfections,
and stochastic beam disorientation and misalignment in order to examine the
throughput performance of a RIS-assisted UAV wireless system. In this
direction, we present a novel closed-form expression for the system's
throughput for two scenarios: i) in the presence and ii) in the absence of
disorientation and misalignment. Interestingly, our results reveal the
importance of accurate modeling of the aforementioned phenomena as well as the
existence of an optimal transmission spectral efficiency.
