The Research Of Probabilistic Routing Based On Node Contact Duration In DTN

With the rapid development of communication technology, more and more telecommunication equipment must configure mobility ability, such as wireless senor network, military network, wild animals tracking network, etc. These networks are characterized by very long delay paths, unsymmetrical data rates and frequent network partitions. To the communication in that special network environment, today's Internet adapt poorly. That network architecture have specialized protocols, which is the Bundle protocol not the TCP/IP protocol. In order to achieve interconnection between them, a new network architecture and application interface had been proposed. This architecture is called delay tolerant networks (DTN).In this paper, the routing protocols about DTN network will be discussed. In original research, many DTN network routing algorithms had been discussed. In these routing algorithms, more representative algorithms are Epidemic Routing and PROPHET (Probabilistic Routing Protocol using History of Encounters and Transitivity). Epidemic Routing is a flooding mechanism. In case of limited cache space, network overhead is large and easily leading to network congestion. Probabilistic routing can provide higher delivery probability and shorter delay, however, network overhead is very large. In PROPHET, whether message can be delivered or not is based on the comparison of node encounter probability. However, nodes are mobile in DTN. Message transmission rate is limited and the successful transmission need some time. Therefore, whether message can be delivered or not which is only through the comparison of node encounter probability has some limitation. Considering contact duration has significant influence on whether message can be transmitted successfully or not, PROPHET-NCD (Probabilistic routing algorithm based on node contact duration) is presented which combine node contact duration with node encounter frequency to estimate delivery probability. Thus it can greatly improve the probability of successfully delivered message and reduce the occurrence of the message transmission interruption. Through the simulation results, we got indicate that this method can achieve higher delivery probability and lower network overhead rate. The paper's main work and innovation are as follows:1. PROPHET routing algorithm calculates and updates encounter probability based on encounter frequency of history. Considering contact duration has significant influence on whether message can be transmitted successfully or not, the concept of message delivery probability is presented which combine node contact duration with node encounter frequency to estimate delivery probability. It can increase the rationality of probability estimation.2. On the basis of message delivery probability, PROPHET-NCD is presented. In the new routing algorithm, whether message can be delivered or not is based on the comparison of message delivery probability. Thus it can greatly improve the probability of successfully delivered message and reduce the occurrence of the message transmission interruption.3. In the simulation, we introduce a new simulation tool, which is the ONE simulator. We use the ONE simulator to build the new simulation environment. Then we simulate the routing algorithm, and compare the results with traditional routing algorithms. Furthermore, the simulation results are analyzed.