dc.description.abstract | Delay tolerant networks (DTNs) contain resource-constrained nodes moving in highly dynamic network environments, which makes persistent end-to-end routing paths impossible between any pair of source and destination nodes. The DTN architecture with the Bundle Protocol (BP) are thus advocated a reliable message delivery service on intermittently connected networks. The BP provides a new encapsulation representation by which a message from an upper layer is divided into a series of bundles. Instead of store-and-forward paradigms commonly used in wireless and mobile ad hoc networks, the DTN architecture adopts the extit{store-carry-and forward} paradigm by which nodes can store bundles, carry them and forward these bundles to next encountered nodes during movement in a network. In addition, BP guarantees delivery reliability among bundles using the extit{Custody Transfer} mechanism. Nodes are not allowed to drop any bundles of which they take the custody until these bundles are successfully delivered to next nodes that can take the custody in turn.
Using the Bundle Protocol in DTNs, however, faces two possible problems. First, opportunistic or unpredictable contacts among nodes may make it difficult for all divided bundles to arrive at a destination, this problem which might enforce the failure of message reconstruction services in a network. Second, the non-dropped feature of custody transfer may cause nodes spend excessive storage space to store custody bundles, this problem which might induce buffer overflow on the nodes.
In this study, we propose a Buffer Management scheme based on Game Theory (BMGT) that nodes can control the number of bundles in their own storage and avoid the likelihood of bundle congestion in DTNs. Regarding the first problem above, BMGT combines the principle of Fountain Code that any destination does not need to receive all divided bundles to recover original message. Regarding the second problem, BMGT derives the appropriate forwarding and receiving probability based on the game theory model, which takes node storage utilization into account, for two nodes in communications. In BMGT, nodes will enter a forwarding game upon contacting with the other nodes and then follow the game theory model to select a forward or receiving action with some merit of reward. To prevent buffer overflow, an incentive function is further devised to encourage reciprocal actions of bundle forwarding and receiving between two nodes in contact. Finally, we conduct extensive simulation to investigate the effects of BMGT under various synthetic contexts. Performance results manifest that BMGT can not only achieve efficient storage resource allocation but also resolve the congestion issue against the convention of Bundle Protocol in DTNs. | en_US |