Research On DTN Routing Protocol

The traditional Internet is based on TCP/IP protocol.The steady operation of TCP/IP depends on the physical link which characterized by continuous,bidirectional end-to-end path,short round-trips,symmetric data rates and low error rates.Unfortunat- ely, a class of network which separated from the traditional network may violate one or more of these characters ,we call it Challenged Network.For instance,terrestrial mobile networks,exotic media networks,sensor networks and so on.In the environme- nt,the new concept of Delay Tolerant Network(DTN) is first introduced and then many researches have been done in the DTN fields,including DTN architectures,routing,DTN model,security and etc.Especially as one of these DTN fields,the mechanism of routing plays a key role in the DTN research.In the DTN,the characters of the long-delay,network patition,low node capacity determine its special DTN routing mechanism on which researchers did much work and a series of algorithms are proposed which fall into two categories:Single-copy routing and Multiple-copy routing.Single-copy routing has the innate advantage of much lower redundancy compared to Multiple-copy routing which suffers from network resource excessive consumption。There is no doubt that Single-copy routing is chosen especially in the resource restricted environment which is common in DTN network.Thus,the Single-copy routing are getting more and more attention these years.In particular,the Utility-based(UB) routing algorithm as the important one of Single copy routing methods can improve the DTN routing efficiency utilizing the historical information on the node movement to predict the future node encounter.Besides,it is very practical to obtain the historical information.Therefore,it is worth to do much work on the UB routing which has great development potential.In the article,we focus on the improvement of the UB routing.In the direction of how to improve the routing efficiency,we did some work as follows:We fist analyze the defects of the UB routing—restricted routing choice and susceptible to DTN congestion. For the former one,we propose Utility-Based with End-to-end Contact in the Cluster(UB-ECC) routing protocol.In UB-ECC routing method ,it is trying to establish the end-to-end contact in the temporary cluster that is formed by the node movement when it is possible which expands the routing selective scope from the previous encounter neighbours to wider range in the temporary cluster.For the latter,we further propose the Utility-Based with End-to-end Contact in the Cluster and Routing Trade(UB-ECC-RT) routing on the basis of UB-ECC routing protocol.The main idea behind UB-ECC-RT routing is to trade the cost of routing regress of low emergency messages for the forward of the routing of high emergency ones.In this way,it efficiently eases high emergency messages of being discarded due to the expiration of TTL and improves the deliver ratio of DTN.To this end,we evaluate the performances of UB-ECC and UB-ECC-RT via simulation which confirms both of them are more efficient in data delivery and average delivery delay than UB routing.