Research On Topology Formation Algorithm Based On Tyson Polygon In Optical Wireless Network

Optical Wireless Communication(OWC)has become one of the important research topics in the area of communication,due to its large bandwidth,high speed and security.However,with the increasing diversity of communication terminals,demand of users and size of network,the point-to-point OWC can not meet the demand of large-scale network.So it is significant to do research on OWC networks.The number of recent research works on OWC networks whose mobile nodes are in medium or high speed is small.Compared with the traditional radio frequency wireless communication,the unique features of OWC including the limited node degree,unstable link,and frequently varying topology increase the difficulty of networking.So as the first step of OWC networking,it is significant to do research on topology formation algorithm.In this paper,a Tesson Polygon based(TPB)topology control algorithm is proposed.TPB algorithm is based on the Tyson Polygon in the graph theory,and employs the hierarchical network structure.The upper topology is a backbone network consisting of the cluster head nodes,and the lower topology includes lots of subordinate networks consisting of noncluster head nodes according to Tyson Polygon.TPB algorithm has the advantages of constructing network topology with higher algebraic connectivity even though the node degree is limited,and adapting to the topology change caused by node movement.This paper designs corresponding node model,energy model and network model which are used to analyze TPB algorithm.TPB algorithm includes three sub-algorithms: the upper node topology formation algorithm,the lower node access algorithm and mobile management algorithm.These three sub-algorithms are employed in three different stages of network topology formation respectively.In addition,this paper proposes a double topological optimization criterion based on the number of subnodes and edge selection weight,which effectively avoids that subnodes is too many to maintain the network energy balance.Finally,for the topology of OWC network,the simulation results of TPB algorithm are analyzed and also compared with minimum spanning tree(MST)algorithm.It is shown that under the same conditions,TPB algorithm has higher algebraic connectivity,averagenode degree,and average residual energy of the cluster head node than that of MST algorithm.Moreover,this paper compares the structures of Tyson Polygon under different topology update cycles.And the simulation results further validate that the local dynamics of the Tyson polygon is able to reduce the change of network topology caused by node movement.