Trajectory Planning for Multiple UAVs in UAV-aided Wireless Relay Network

The integration of Unmanned Aerial Vehicle (UAV) as flying base station (FBS) assisted wireless communications has recently attracted significant attention. However, there is a need for efficient optimization trajectory techniques to allow for continuous service connectivity for FBSs operating at regions beyond single-hop backhauling to their depot (i.e., fixed macro base station). This work proposes an optimization trajectory planning framework to provide continuous service delivery of FBSs by utilizing aerial relay nodes which can also serve ground users (GUs). The proposed joint optimization framework of FBSs trajectories where a subset of them acts as relay nodes called relay-FBS (rFBS) provides tangible gains compared to previously proposed nominal techniques. More specifically, a wide set of numerical investigations reveals that the proposed framework reduces aggregate travel time (ATT) more than 14% for the entire fleet of FBSs, whilst for rFBS to enable continuous service support, this average gain is more than 38%.