Research On Dynamic Spray And Wait Routing And Congestion Control Strategy In DTN

Delay/Disruption Tolerant Network (DTN) is an opportunistic network. In order to improve packet delivery reliability of this opportunistic network, DTN uses multi-copy mechanism to increase the packet delivery probability. Multi-copy routing mechanism allows the same packet to be forwarded to multiple intermediate nodes and submitted to the destination node through multiple paths. So researching the characteristics of challenged network environment and proposing effective multi-copy routing mechanism have great significance.However, multi-copy routing mechanism achieves the communication in challenged network environment, which causes a large amount of redundant packets be forwarded in the network and the network resource and energy be consumed greatly at the same time. Because storage space is limited, multi-copy mechanism will lead to congestion at the node easily. So we add appropriate congestion control strategy based on DTN routing protocol to discard redundant copies reasonably in storage, which plays an important role in improving network performance and the robustness of the routing.In this paper we first analyzed and summarized the concept, architecture and several typical routing protocols of DTN and focused on analyzing spray and wait routing protocol. According to these problems, we proposed following programs:1. The spray and wait routing protocol will spray a half number of copies to the intermediate node. So it is blindness when forwarding the copies. This paper we considered the difference of node activity, then proposed the dynamic spray and wait routing protocol based on node activity (DSW-NA). This protocol sprays copies dynamically based on the ratio of node activity, thereby increasing the packet delivery utility and improving DTN performance, such as packet delivery ratio and delay.2. In this paper, we analyzed the relationship between the number of copies and valid of packet based on DSW-NA. We proposed the congestion control strategy based on DSW-NA (DSW-NA (Drop)). DSW-NA (Drop) routing will drop packets reasonably. It reduces the transmission of redundancy packets and makes more valuable packets can be stored and forwarded. It improves DTN performance, such as packet delivery ratio and overhead ratio. It makes the DSW-NA routing having the function of congestion control and makes the routing having better robustness.3. In this paper, we used the ONE (Optimistic Network Environment) simulator to evaluate the performance of dynamic spray and wait routing and congestion control strategy. Then we compared and analyzed the simulation results.