“…More recent results have considered on the one hand, advanced physical layer communication techniques such as high-throughput relaying using buffer onboard UAVs [30], directive transmission using high-gain directional antenna and gimbal-assisted adaptive antenna steering [31], beamforming using aerial reconfigurable intelligent surface (RIS) [32], and exploiting multiple UAVs for cooperative multiple-input multiple-output communications [6]. On the other hand, to fully exploit the benefits of these physical layer techniques, joint optimization of UAV deployment, trajectory planning and resource allocation have been considered for optimization of cell coverage [33], throughput, energy [6], [31], and mission completion time [30], [34]. In addition to dynamic trajectory planning [6], [30], [34], optimal selection of waypoints has been considered in [31] to fulfill requirements of e.g.…”