Graph-Based Time Expansion Routing Scheme for UAV-Assisted Emergency Networks

An effective communication is crucial yet challenging due to the damage sustained by ground communication infrastructure. A promising solution for enhancing emergency communication involves leveraging long-endurance fixed-wing UAVs to act as communication relays for ground rescuers. However, the disastrous environment and dynamic characteristics of UAVs may cause intermittent connectivity states, hindering efficient data transmissions. This study addresses data transmission issues in the fixed-wing UAV networks by proposing a routing scheme that leverages pre-defined UAV trajectories and tackles the dynamic topology using a graph-based time expansion method. Specifically, we propose a graph-based modeling approach to unfold network topology over time incorporating the packet transmission constraints. Then, the time-averaged delay minimization routing issue is transformed into a static linear programming problem, which is solved at each time step to minimize the packet delay and improve the network reliability. The experiment results reveal that the proposed approach outperforms the existing methods in terms of average packet delay and packet delivery ratio.