Social-based Routing In Delay Tolerant Network

Unpredictable mobile characteristics of nodes, the lack of global information, so that Delay Tolerant Network(DTN) routing algorithm is extremely challenging to design. Because the structure of the entire network constantly chang es over time, there is no fixed path, so the traditional routing algorithms can not be applied to Delay Tolerant Network. So we use the "storage carry and forward" strategy, the source node first stores the message and carries the message then forwards it until the time appropriate condition happens. Researchers tend to focus on research of promoting the delivery ratio of the network and reducing the load of whole network. In recent years, due to the popularity of mobile devices, researchers have begun to join the social characteristics of network to the routing algorithm.In this paper, we construct the algorithm model in terms of friend relationship between nodes. After analyzing the advantages and disadvantages of current routing algorithm based on friendship, we find that it can not differenciate the contact distritution. Based on this, we add contact distribution characteristics of historical encounter information into the evaluation. That can reflect the reality of the situation better. In the part of buffer management, by the analysis of existing algorithms, we found that they just consider the maximum delivery ratio of local node, or just consider the copy number but don’t differenciate them. So we record the node information where the copy is located, then propose the global copy utility. When the copy number of one message reaches a resonable value, and it has a higher delivery ratio, then we’ll give it a lower weight, and guide the memory management by this.After the simulation, we get the algorithm performance indicators: delivery ratio, network overhead, average transmission latency and so on. After comparison with the original algorithm based on the friendship relationship, we found the delivery ratio and network overhead is better than the former algorithm. At last, we integrated the routing and memory mangement, and call it NFCU(New Friendship with Copy Utility). After the comparison with current algorithms, we found the algorithm we propose always gets a better performance when the network is memory thirsty.