Research On Fault-Tolerant Topology Control Algorithms In Flying Ad Hoc Networks

Flying Ad Hoc Network(FANET),as a new solution for UAV cluster ad hoc communication network,has attracted extensive attention in the field of UAV research.Due to the longer distance between UAVs and the network is sparser,the existing topology control technology based on traditional Ad Hoc network has some limitations in FANET.Network connectivity is the basis of data transmission and collaborative interaction between UAVs.When k(28)1,the network satisfies single connectivity;when k ?2,the network has fault-tolerant capability,so topological connectivity is the basic goal of FANET fault-tolerant network.Therefore,focusing on the fault-tolerant control of FANET network,the paper studies the topology control method of FANET network based on three-dimensional space,which guarantees the continuous end-to-end reliable connectivity between UAVs through topology simple-connected and two-connected control.The main research contents are summarized as follows:(1)Modeling the FANET network topology,analyzing the node and network topology structure in the network with the knowledge of graph theory.Introducing the exchange mode of multi-hop information in FANET network.Firstly,based on large-scale fading,a wireless channel transmission model is established.Then,the relationship between maximum transmission distance and transmission power is analyzed.In addition,the feasibility of replacing the change of power with the change of distance is pointed out.Finally,the related theory of network topology control is introduced,and the feasibility of realizing simple connected network and two connected fault-tolerant networks through UAV mobile network topology control is illustrated.(2)Single-connected topology control of FANET network.To solve the problem of network partion,we proposed the network topology control algorithms based on artificial potential energy field.Based on the Boid model,Vicsek model and FANET network model,the direction information,forward view information and artificial potential energy field are introduced to adjust the movement speed and improve the convergence speed of the algorithm,which can make the UAV cluster network maintain a high connectivity during the movement process.Moreover,the average node degree of the obtained network topology is approximately equal to that of the initial network topology,and the network density will not be increased.It solves the problem that dynamic FANET network topology is easy to be segmented and maintains the connectivity of wireless communication network of UAV cluster.The simulation results show the effectiveness of the proposed method.(3)Bi-connected fault-tolerant network topology control.To solve the problem of easily segmented single-connected networks,we proposed the Fault Tolerant Algorithm in Localized Topology Based on Node Movement Freedom Degree to realize bi-connected fault-tolerant networks.Firstly,based on the k-hop local topology of UAV nodes in three-dimensional FANET,a cut-point detection algorithm based on neighbor change is proposed.The computational complexity of the algorithm is analyzed,and the consistency between k-hop and global cut-point is studied by numerical CBNC simulation.Then,the movement freedom degree model of node movement is established,and three cascade movement strategies are proposed according to the distribution of cut-points in the k-hop local topology of cut-points.The problem of constructing a bi-connected fault-tolerant network is transformed into the problem of eliminating global cut-points in the network.The performance of FTLMF algorithm in three-dimensional FANET network is studied by numerical simulation.The simulation results show the superiority of the two algorithms in cut-point detection and fault-tolerant control.