Design And Implementation Of Multi-policy Routing Algorithm In Rongchao Network

Delay tolerant networks(DTN)are a type of wireless mobile networks,characterized by a lack of continuous end-to-end connections due to node mobility,dynamic network topology,constrained power sources and limited data storage space.In this case,message transfer in DTN is in hop by hop “store-carry-forward” manner.Thus,how to make correct and efficient routing strategy becomes a hot topic in DTN.The main contributions of this thesis focus on selecting relay nodes to make routing strategy more efficiently.The main contents include three aspects:(1)Similarity Based probabilistic routing.We study node history contact information to extract node social similarity.And we try to avoid message redundancy by transferring message based on node similarity.The statistical method is used to estimate node encounter probability.This utility function can transfer message copies in target region.(2)Social popularity based routing.The node moving track is taken as the research object to filter out stranger nodes.We call nodes that are tightly linked to the given node as neighbor nodes.Degree Centrality only takes one-hop contact information into consideration.To overcome the problem,we propose a metric called social popularity based on relationship among neighbors.(3)Social popularity based probabilistic routing.We propose a social group-aware model to design a heuristic function.By taking node inter-contact time and message remaining time-to-live into consideration,we predict the probability that the given message can be successfully delivered directly and indirectly.And then we devise a specific data item selection mechanism for probability-based routing,which is modeled as 0-1 knapsack optimization problem and solved by the backtracking algorithm.In this case,the node buffer resource is used reasonably.The message routing process is divided into two phases: routing inside destination group and routing outside destination group.Extensive simulation results have proved the reasonability and efficiency of the work in the thesis.The proposed three algorithms achieve great performance in delivery ratio and network overhead.And the work possesses theoretical and practical significance for routing design in DTN.