Analysis Of Connectivity Monitoring Model In Opportunistic Sensor Networks Based On Evolving Graph

In an Opportunistic Sensor Network(OSN), the sensing area is often cut apart into several separated areas due to special terrains or the ever-changing communication quality. Each area communicates intermittently through mobile nodes or so called Ferries moving near by. The connectivity is opportunistic, discontinuous and dynamic caused by continually topology changing of the network. These features has brought a great challenge for establishing a connectivity model of OSNs, and for monitoring a running one. It is important and meaningful for network monitoring to build a connectivity model of OSNs. This program is focus on the establishment of a connectivity monitoring model of OSNs.The thesis introduces the concept of the OSN and the related works of the connectivity researches. After analyzing the connectivity features of OSNs, it takes evolving graphs to describe snapshots of an OSN, and it builds an evolving graph model for the connectivity. It redefines connectivity parameters of OSNs based on graph theory. It also proposes algorithms for building the evolving graph model and calculating the connectivity parameters. Furthermore, it establishes a connectivity monitoring model of OSNs. The feasibility of the model is verified by simulation and test bed experiments.During the test bed experiments, we discovered a few insufficiencies of the proposed model. The thesis improves the original model 4 times with calculating the minimum node degree and using sliding windows, etc. Finally, the connectivity monitoring model is improved by a calculation method of network connectivity degree with a decision rule.Experimental results show that the network connectivity degree calculated by the proposed network connectivity model highly matches the actual message delivery rates,and the connectivity model established in this thesis is applicable to monitoring an opportunistic sensor network.