Research And Simulation On Topology-Based Fault Diagnosis Algorithm In The Space Information Network

The space information network is an integrated information network, including the systems of land, ocean, air and sky. Due to its particular characteristics, such as long communication distance, wide overlay area and without geographical restrictions, it has great value in the detection, communication and positioning application field. As the space information network is usually working in poor or hostile environment, it is easily destroyed and interfered and thus its quality of service declines. Finding, diagnosing and locating faults accurately and quickly enable network to operate safely, reliably and stably.Considering characteristics of the space information network, a distributed topology fault diagnosis algorithm is proposed. This algorithm is composed of three modules, which are diagnosis node election module, fault detection module and fault level assessment module. Diagnosis node election module elects proper number of nodes to detect network faults in a coordinated and distributed way by using minimum dominating set algorithm. In fault detection module, elected diagnosis nodes detect faults around based on the theory of dependency-graph and send packets to locate faults further. Fault level assessment module identifies fault level both according to the extent of harm to network and the cost of reconfiguration, which is achieved by evaluation of node and link importance. Network connectivity and specific requirements of different services under multi-application environment are combined as the measure of network reliability in evaluation process, which provides the basis for the realization of network reconfiguration.The network simulation software NS2is adopted to evaluate the proposed fault diagnosis algorithm. Simulation results demonstrate that high accurate judge rate can be reached at the expense of low cost by this fault diagnosis algorithm. Furthermore, outputs of fault level assessment module are more reasonable comparing to the true results in real multi-application environment, which guides network to make a good choice of reconfiguration schemes.