Topology construction and topology adjustment in flying Ad hoc networks for relay transmission

A flying ad hoc network (FANET) is formed by multiple unmanned aerial vehicles (UAVs) in an ad hoc manner in which UAVs can cooperate more effectively to complete complex tasks. In this paper, we mainly investigate the topology construction and topology adjustment for FANETs in which relay UAVs are used for relay transmission between mission UAVs and a ground control station (GCS), so that each mission UAV can communicate with the GCS through a multi-hop communication connection. Firstly, we propose an alternating optimization algorithm to optimize the routing paths and the positions of relay UAVs alternately, so as to construct a feasible FANET topology using the minimal number of relay UAVs. Then, we propose a greedy algorithm to deploy new relay UAVs to the FANET topology constructed by the alternating optimization algorithm, so as to construct a high-performance FANET topology using the given number of relay UAVs. Both the alternating optimization algorithm and the greedy algorithm need to be executed in a centralized manner, so these two algorithms can only be used for FANET topology construction. Furthermore, we propose a distributed algorithm to adjust the existing FANET topology when the positions of mission UAVs change, so as to improve the FANET network performance. This distributed algorithm can be executed in a distributed manner, so this algorithm can be used for FANET topology adjustment. The simulation results show that the algorithms proposed in this paper are superior to other baselines.