Integrated Topology Management in Flying Ad Hoc Networks: Topology Construction and Adjustment

Flying ad hoc networks (FANETs) that consist of multiple unmanned aerial vehicles (UAVs) are promising technologies for future networked systems due to the versatility of UAVs. One of the most distinguishing features of FANET is frequent and rapid topological fluctuations due to the high-mobility of UAVs. Hence, the topology management adapting to the movements of UAVs is one of the most critical issues in FANET. In this paper, we study a FANET topology management problem that optimizes the locations and movements of UAVs to maximize the network performance, adapting to the topological changes while UAVs carry out their missions. When formulating the problem, we take into account the routing protocol as an arbitrary function since the network performance is inseparably linked with the routing protocol in use. We first develop two algorithms. One is the topology construction algorithm, which constructs a FANET topology from the scratch without any given initial topology, based on particle swarm optimization. The other is the topology adjustment algorithm, which incrementally adjusts the FANET topology adapting to the movements of UAVs with low-computational costs, based on gradient descent. Then, by defining a logical distance (the so-called topology edit distance) that measures the degree of changes in FANET topology, we develop an integrated topology management algorithm that contains the topology construction and adjustment algorithms. The simulation results show that our algorithm achieves a good network performance with low computational overhead, which is one of the most essential virtues in FANETs with rapidly varying topology.