Research On Routing Protocol In Delay Tolerant Networks

The appearance of plenty of devices equipped for short-range wireless communications boosts the fast rise of wireless networks. In real networks, node mobility, dormancy, electromagnetic interference, lossy link and low density result in frequent network partitions, not existing a fully connected path between the source and destination, which make the existing traditional routing protocols could not work well. To achieve interoperability between networks which have long delays, frequent partitions and low delivery ratio, researchers had proposed a new network architecture which is called delay tolerant networks (DTN). As long as the nodes move randomly, they can transmit the messages hop by hop in networks in the form of"store-carry-forward"paradigm by taking the communication opportunity of mobility. Thus, how to transmit messages through a network which changes continuously over time has become one of the key and difficult subjects.This paper will firstly introduce the concept, features, key technology and application domain of DTN, and then make a deep analysis for Epidemic protocol and Spray and Focus protocol, which are two main routing protocols in existing DTN. Secondly, considering that Spray and Focus mechanism choose node blindly in the"spray"phase, we propose a new protocol called"EPI-T"to select the next hop node on the purpose of forwarding packets accurately, which impenetrate the concept of"separation time"into the whole process of routing. Then based on EPI-T, we proposed"EPI-BMT", which introduce the"separation time"into buffer management to improve buffer's utilization rate and inhance the chances of successfully arrived data packets. In the end, the third protocol called"EPI-MCT"is proposed by applying"separation time"into multicast routing, which require the node maintain the link status of neighbor nodes, in order to share information of group members, as well as conserve resource and improve performance efficiently.In this paper, we chose NS-2 as simulation tool to make simulation and performance estimation for Epidemic protocol, Spray and Focus protocol, and their improved versions, and the simulation results show that contrast to the Epidemic protocol, Spray and Focus protocol,improved EPI-T protocol, EPI-BMT and EPI-MCT protocol preform excellently on delivery ratio, End-to-End delay and source cost.