  The effective integration of unmanned aerial vehicles (UAVs) in future
wireless communication systems depends on the conscious use of their limited
energy, which constrains their flight time. Reconfigurable intelligent surfaces
(RISs) can be used in combination with UAVs with the aim to improve the
communication performance without increasing complexity at the UAV side. In
this paper, we propose a synergetic UAV RIS communication system, utilizing a
UAV with a highly directional antenna aiming to the RIS. The proposed scenario
can be applied in all air-to-ground RIS-assisted networks and numerical results
illustrate that it is superior from the cases where the UAV utilizes either an
omnidirectional antenna or a highly directional antenna aiming towards the
ground node.
