Re-configuration of UAV Relays in 6G Networks

Unmanned aerial vehicles (UAVs) can be widely applied as aerial relays in 5G and beyond to provide communication services, since they are cost effective, provide large coverage, and can be deployed fast. In a UAV relaying network, each UAV is responsible for the communication of its ground cell. When a ground user intends to transmit traffic to a destination ground user, the data might be transmitted in a multi-hop manner over several UAVs. To this end, each UAV can transmit data to its neighboring UAVs over air-to-air wireless links, which in general have limited capacity. As data transmission is needed between multiple pairs of ground users, several connections will exist simultaneously in the UAV network. Each connection has a bandwidth and occupies some specific time slots of air-to-air links. Due to link failures and network agility, network resources might not be efficiently utilized by the connections, resulting in the refusal of new connections. Therefore, route management and resource allocation should be frequently renewed in UAV-assisted networks. In this paper, using an integer linear programming formulation, we first derive an algorithm for route refreshment. Since the link capacity is limited, the resource assignment of new routes plays an important role in the connection migration. The second goal of this paper is deriving a necessary and sufficient condition for the existence of disruption-free connection migration. Finally, we study the average percent of disruption and resource utilization reduction in a sample UAV relaying network.