Researchn On Mobility Model-Driven Buffer Management Of End Nodes In Delay Tolerant Networks

Delay Tolerant Network(DTN)has many characteristics,e.g.,intermittent connectivity,topology frequent lacerate,limited resources,sparse node density and mobility,which makes it hard to maintain an end-to-end path between the message sender and receiver.In order to storage messages in nodes' buffer for a long time,messaging usually adopts the routing mode of "storage-carry-forward".It is important for DTN to manage nodes' buffer space effectively and design practical buffer management policy,which can improve the delivery rate of messages in the network and reduce network ratio.Because the nodes usually move regularly in the network,this thesis designs the buffer management mechanism with lower latency and higher resource utilization.Therefore,this thesis mainly focuses on investigating the mobility model-driven buffer management mechanism in DTN.Combining the time-to-live of messages and the number of copies of messages,the characteristic of mobility,buffer dropping policy as well as buffer scheduling policy are researched by analyzing the characteristics of different mobility model,including random mobility model and vehicular mobility.The concrete content is as follows:1)This thesis firstly analyzes the random mobility model and explores the characteristic of nodes' mobility,and then calculates the weight value of messages combining with global network knowledge,as well as designs the priority formula of messages.Finally,a random mobility model-driven buffer management mechanism is proposed.2)This thesis studies the feature of vehicular mobility model and uses the characteristics of nodes' unfree as well as architectural barriers,and designs a fine-grained vehicular mobility model-driven buffer management.The buffer management mechanism is implemented to improve the performance of DTN by setting the priority of messages.The dropping policy is the node drops the lowest priority of messages firstly and the scheduling policy is the node forwards messages by the priority of messages from high to low.3)This thesis does the simulation experiment of proposed buffer management mechanism,and verifies the performance of this mechanism using different routing policies and experimental data in messages delivery ratio,average delay,network overhead and average hop count under different mobility scene.