Research Of Connectivity Model For Opportunistic Sensor Networks Based On Temporal-spacial Graph

Opportunistic sensor networks(OSNs)are a type of self-organized network that does not require complete communication paths between source and destination.They utilize contacting opportunities of Ferry nodes to achieve data communication so that they can attain the regional information with low cost.They also have high delay,frequent split and intermittent connection characteristics,which are derived from the delay tolerant networks(DTNs).Unlike Ad hoc networks,OSNs have many disconnected sensing regions,these sub-regions can only send messages to Sink node by Ferry nodes.The frequent mobility of nodes cause the topology of OSNs dynamic and time-evolution,so it is hard to model OSNs connectivity by tradition methods.The connectivity model can help us analyze the network connectivity conditions,provides bases for designing routing protocols and data diversion strategies.It can also help us improve the operation status of nodes and optimize network topology.The project is supported by the National Natural Science Foundation of China,studies the connectivity of OSNs.This thesis introduces the basic concept of OSNs,elaborates the research status of network connectivity.The OSNs connectivity model is constructed based on temporalspacial graph.From the message transmission aspect,this thesis utilize the journey to describe the evolution of end-to-end connectivity,define temporal and topological distance based on message transmission characteristics in temporal and spacial level.Then temporal distance and topological distance of each snapshots are used to construct network connectivity model based on message transmission.Through the simulation results,it can verify the feasibility of the model,but the model is not suitable for the scenarios with similar connectivity.From topological aspect,this thesis defines the connectivity parameters such as node degree and node connection strength to describe the OSNs' links between nodes.Considering the edge establishment characteristics of OSNs,the thesis divides OSNs into two layersRegion-Ferry layer and Ferry-Sink layer,define connectivity indexes to describe the connectivity in each layer.Then combines the connectivity indexes to construct overall connectivity model.The simulation results show that the overall connectivity is basically the same with the actual delivery success rate of messages,which can reflect the network connectivity under different scenarios.