Research And Simulation On DTN Network Routing Algorithm

DTN network is a new type of mobile Ad Hoc network. Due to its characteristics such as long communication delay, high dynamic topology, sparse distribution of nodes and frequent link break, it is difficult to maintain the stability of end to end path. Therefore, the traditional wired or wireless network routing protocol cannot be directly used in DTN network. Design of effective and reliable routing algorithms has become the key issue in DTN network.A DTN routing algorithm with the thought of "storage-carry-forward" is proposed in this paper. Source nodes don’t establish a complete route to destination nodes to send data packets. However, a source node selects an appropriate node as a data carrier called "relay node" in the context of that the end to end route cannot be established. Under this circumstance, the relay node receives packets, stores them and then finds the destination or a better relay node to forward packets. Through hop-by-hop storage-carry-forward strategy, packet will finally arrive at the destination. In the storage-carry-forward process, routs are constructed by considering characteristics of DTN network. Although DTN network topology is frequently changing, nodes within local area may be strong connected in a short time and thus can provide a path from source or relay nodes to destination or better relay nodes. So Ad Hoc Network routing strategies are used to improve network performance.For the two cases of that motions of DTN nodes are predictable and unpredictable, we design relay node selection schemes respectively. For the case of motions of DTN nodes are predictable, a virtual Euclid space is constructed, which divides the network into N regions. According to motion regularity of nodes, virtual coordinates of each node are calculated off-line. Nodes choose relay nodes with smallest virtual Euclid distance to the destination nodes within their communication range. For the case of motions of DTN nodes are unpredictable, nodes periodically broadcast Hello packets. Nodes real-timely maintain information table of transmission probability to other nodes depending on whether receiving Hello packet from other nodes. Nodes will choose relay nodes with biggest transmission probability to destination nodes when delivering packets.NS2network simulation software is used to analyze the validity and reliability of the proposed DTN routing algorithm. Comparing with AODV routing protocol, PRoPHET routing protocol in terms of three metrics, network successful delivery ratio, network traffic and communication delay, simulation results show that the proposed algorithm has better performances and it’s suitable for DTN network applications.