A Routing Scheme Based On Spray-and-Wait And Connecting-Capability Of Node

The rapid development of the Internet makes people around the world,lifestyle and working ways have taken place great changes.As is known to all,science and technology are constantly innovate,but under some special occasions and specific conditions,the traditional network still cannot satisfy the demand of human beings.Such as,the serious earthquake,geological disaster,fire,etc.Where the communications infrastructure will be seriously destroyed,so people cannot communicate with the outside,therefore human beings should constantly explore new technology to solve the problem,and at that-time DTN is suitable for this challenging environment.Based on the inherent structure and feature of DTN,researchers have proposed many DTN routing algorithms.Such as Spray and Wait,Prophet,and Epidemic,etc.They make the messages in flexible transmission,but also have shortcomings.For example,the routing algorithms do not take the difference between the performances of node into account when the nodes forwarding replications.In addition,the phenomenon such as network congestion and a large amount of wasted resources often appear.In this thesis,we present an improved routing scheme synthetically measure relay node's forward capability,dynamically distribute message replications.To some extent,the network performance improved significantly.This thesis mainly introduces the architecture of DTN network,a few classes routing algorithms of DTN,and studies Spray and Wait routing algorithm in depth,roughly finished work as follows.Firstly,this thesis introduces the research background of DTN,the status quo of DTN research at home and abroad are analyzed,then a detailed introduction about the origin of DTN and its application in the real life.Secondly,the encounter historical information between the nodes may portend the future connection opportunity including the encounter frequency,total contact period,average contact period and average separation period.The greater the frequency of the encounter,the more frequently messages exchange;the longer the duration of the meeting,the more the number of messages exchange.Therefore based on historical information,the average separation time is presented,which not only reflects the contact frequency but also reflects the length of the encounters.Thirdly,on the basis of the average separation time,this thesis puts forward the concept of Node Connection Intensity(NCI),to some extent,it is conducive to improve the performance of the node,so the bigger NCI indicates the better the performance of node.Considering whether the node connection is stable or not,based on the average separation time,this thesis presents Node Connection Stability(NCS),and uses the root mean square value of the average separation time to measure the performance of node,lager NCS will better to node.Fourthly,this thesis proposes a routing scheme based on Spray-and-Wait and Connecting-Capability of Node(SW-CCN),which evaluates relay node's forward capability synthetically according to the NCI and the NCS.Then uses the ONE to simulate the SW-CCN routing algorithm,and compare with the traditional routing algorithms.To sum up,this thesis puts forward a routing algorithm based on CCN,it can not only enhance the delivery rate of messages,but also reduce the overhead ratio,which has certain theoretical significance and useful value.