Resource Share Mechanism In Disconnected Ubiquitous Stub Network

As the rapid and extensive development of the network,a large number of heterogeneous terminals are distributed around the edge of the network and users,forming a ubiquitous stub environment for users to carry ubiquitous services.Due to the limited resources and the uncertain mobility of terminals,the network topology changes dynamically,so resource sharing in network is a challenging problem.In disconnected ubiquitous stub network,a temporary path cannot always be established between any pair of nodes:end-to-end connectivity is thus not guaranteed.Meanwhile,the success of resource discovery and sharing is influenced by opportunistic contacts between pairs of terminals in disconnected topology.Therefore,how to realize resource discovery and sharing efficiently in disconnected topology has become the focus in this paper.To realize resource sharing among terminals in disconnected scenarios,two key issues need to be solved:clustering terminals in connected areas and resource routing planning in disconnected areas.By clustering the terminals in cluster,all cluster heads are selected as directory nodes to collect and manage the resource information in cluster.Through resource routing planning,requests and returns of resources in disconnected areas are completed,which effectively supports resource sharing in the network.Firstly,aiming at the clustering problem of intra-group terminals in connected areas,this paper proposes a cluster mechanism based on mobility prediction of nodes,the movement of nodes are analyzed and predicted,the cluster structure is adjusted adaptively,the stability of cluster structure is improved.First,the Doppler shift is used to calculate the relative moving speed and obtain the link expiration time between nodes.Then,during the cluster formation stage,the MAX-MIN heuristic algorithm is used to select the cluster head according to the average link expiration time of the node.Furthermore,during the cluster maintenance stage a network adaptive adjustment method is proposed based on node motion.On the one hand,the node information transmission cycle is adjusted to balance the data overhead and accuracy;On the other hand,the cluster structure is adjusted by predicting the link disconnection to reduce link reconstruction time and improve the quality of network operation.Simulation results show that the proposed algorithm can effectively prolong the duration of cluster head and improve the stability of cluster structure in dynamic environment.Furthermore,to solve the problem of inter-group resource routing,this paper proposes a routing mechanism based on the probability of node encounter,which uses mobile devices to transmit resource information between groups.Firstly,the probability model of node encounter is established.Then,on the basis of predicting the probability of node encounter,aiming at minimizing end-to-end delay,the model of minimum expected delay routing selection is established.Finally,a model based on minimum expected delay is designed.The inter-group resource routing algorithm can complete end-to-end path planning and realize opportunistic inter-terminal routing.The simulation results show that the routing algorithm considering the probability of node encounter can effectively reduce the average end-to-end delay with the increase of path length,and can be applied to mobile and disconnected ubiquitous stub networks.The resource sharing mechanism proposed in this paper,especially terminal clustering algorithm and resource routing algorithm,improves the stability and effectiveness of resource sharing,and has a certain significance for resource management in ubiquitous stub environment.