Research On Routing Protocols In Opportunistic Networks

Opportunistic network is a novel kind of Mobile Ad hoc Networks (MANET), which takes full advantage of the node mobility and opportunistic contacts to transfer information. Practical Ad Hoc networks have problem with data communication because of frequently disconnections, then, opportunistic networks were proposed to solve this important communication problem. Since an end-to-end path between the source and the destination may never exist, traditional wireless routing protocols will break in this kind of environment. Hence, routing protocol design is one of the main challenges in opportunistic networks. In This paper, we focus on the routing technology in opportunistic networks, carry out intensive analysis and research and finally get some meaningful achievements.This thesis first makes a deep research on routing protocols in real-life scenarios where the location information of mobile nodes is available. Considering the practical mobility characteristics, a new interpolation prediction algorithm of mobile location is proposed to solve the current problem of speed prediction, and also expands the scope of mobility prediction algorithm. After that, a routing protocol based on the mobility prediction is proposed. In spray phase, multiple copies of the message are distributed in a binary tree way, which can improve the transmission performance and effectively control communication overhead. In forwarding phase, when a node carrying a message copy encounters another node, it will carry out mobile location prediction, and forward the message to the node which will be closer to the destination in the future. This routing protocol reduces the complexity of mobile information collection, and solves the classic routing protocol's problem in delivering messages caused by just waiting to encounter the destination. The proposed routing protocol achieves a better performance in the message delivery probability and delivery delays.This thesis also develops a routing protocol based delivery probability in general opportunistic networks scenario. In this algorithm, the nodes contact frequency and reliability of the link are used in calculating and updating the delivery probability. In order to avoid interruption in the transmission, links with long contact duration are preferred and it will improve the message transmission reliability. In the forwarding phase, when the node carrying message copy encounters another node, it will forward the message to the relay node with higher delivery probability and long contact duration. Meanwhile, this protocol deletes redundant messages in buffers proactively. This mechanism can reduce the message discarding due to no buffer space, and further improve the message delivery probability. Then, from the point of the message aggregation and divergence, we prove this routing algorithm is effective in theory. This protocol takes full advantage of network context from observation in general opportunistic network, it achieves a higher message delivery probability with lower delivery delay, leading to strong applicability and scalability.