Coordinated trajectory planning for efficient communication relay using multiple UAVs

• A nonlinear model predictive control based communication relay strategy is proposed.
• The motions of ground mobile nodes and relay UAVs are predicted for optimization.
• Deploying UAVs can improve the network connectivity in a mobile ad hoc network.
• The improvement rate becomes less significant as the number of UAVs increases.
• The improvement becomes significant when mobile nodes have a low transmission power.

This paper investigates the use of small UAVs as communication relay nodes for expanding communication links and improving communication quality for a fleet of naval vessels. This paper firstly deals with the UAV deployment for stationary communication nodes, and then, proposes a decentralised nonlinear model predictive trajectory planning strategy for a dynamic environment. By exploiting motion estimates of vessels and states of UAVs, the trajectory planning algorithm finds a control input sequence optimising network connectivity over a certain time horizon. Numerical simulations are performed for both stationary and manoeuvring vessels to verify the feasibility and benefit of the proposed approach.