A Research Of Social-based Routing On Delay Tolerant Networks

The Delay Tolerant Networks (DTN) is a new type of resource restricted network is different from TCP/IP Networks. Different from MANET, the transmission path in DTN is unstable. Therefore, it is hard to predict a specific time delay for the message that transmit to the destination node. Besides that, since DTN is a resource restricted network, the nodes' capacity will be restricted in network and data packet loss also frequently occurred. To solve these problems, Many DTN routing algorithm have been put forward.Currently, there are many DTN routing algorithms with the message copy number.The algorithms usually be divided into single copy forward routing algorithm and multi-copy distribute routing algorithm. The single copy forward routing in DTN is suitable for application in the field environment, it always keeps one copy of each message. Although in this way will maintain a low rate of congestion and reduce resource consumption, also will lead to a low success delivery rate because of mobile node connecting channels disconnected. On the contrary, the multi-copy routing algorithms improve their success delivery rate by increasing the copy number of messages.Since DTN has many problems, such as node often change position that can't be predicted and the network structure is changeful. To solve these problems we propose several DTN routing algorithms based on social attributes.(1) Improve the Motion state-based Routing for DTN. The traditional routing algorithm can't meet the expected delivery rate. So, we propose the motion state-based routing for DTN. It will get the geographic information of mobile node with a certain frequency. According to the mobile node has social attributes,regular change the position and the characteristics of the movement trend foreseeable. The algorithm will compute nodes' movement distance and direction and then select the flood routing to distribute messages based on motion weight.(2) The existing DTN routing algorithms tend to make data transition inflexible and have a long delay in contact. To solve these problems we propose a routing algorithm which called Meeting delay expect value in spray and forward routing algorithm for DTN (MDESF). This algorithm will use mobile node's contact history to conduct the expected average contact/disconnect time and message expected wait value (EWV). With those attributes the MDESF will proportionally distribute multiple replicas of a message between two contact nodes in the message's multiple replicas phase. And in case of a single replica of a message,MDESF makes the routing decision by comparing two encountering nodes' utility value. We also propose the buffer management strategies for the protocol. The simulation results illustrate that our proposed MDESF protocol outperform other existing ones.(3 )We proposed A Hybrid Clustering Routing Method Based on Social Metrics in DTN. This algorithm can be divide into two stages. The first stage is called mobile node clustering phase, in which the algorithm will cluster nodes with similar centricity, because they have similar behavior and will often contact each other. So we can see cluster as a mobile node. The second stage is called routing distribute phase. At this phase, to achieve the optimal message delivery the routing algorithm will choose different strategies depending on the destination node forwarding message.This paper draws on predecessors' excellent ideas in routing algorithm and optimize the related algorithm. Besides that, we also propose some new thoughts to improve performance. Such as combine queue management method with message delivery strategy and use social attributes to enhance routing.