Routing and Network Design in Delay Tolerant Networks.
Routing and network design in delay tolerant networks(2006)
摘要
Delay tolerant networks (DTNs) are an important class of emerging networks that exhibit significantly different characteristics from today's Internet, such as intermittent connectivity, large delay, and high loss rates. DTNs arise in a variety of environments such as disaster relief, military, rural Internet access, environmental sensing and surveillance, deep space communication, underwater sensing, and inter-vehicle communication. While not the common case for networking, these environments represent some of the most critical cases, where the ability to communicate can make a huge difference for human lives. Supporting effective communication in DTNs, however, is challenging. First, with intermittent connectivity, DTNs are often extremely resource-limited and not able to deliver performance required by applications. Second, given resource limitations and uncertainty in DTNs, it is critical to deliver data efficiently and robustly. The situation is especially acute for multicast which sends data to multiple destinations. This thesis seeks to address these two issues. To enhance network capacity in DTNs, we propose a message ferrying scheme that exploits the use of special mobile nodes (called message ferries) and controlled device mobility to deliver data. Inspired by their real life analog, message ferries are utilized to transport data via mobility between sources and destinations. We develop a foundation for the control of the mobility of message ferries, and nodes if possible, to cooperatively deliver data. Specifically, we address the following issues: (1) development of algorithms to design message ferry routes in networks with stationary nodes and a single ferry; (2) development of algorithms to design message ferry routes in networks with stationary nodes and multiple ferries, where interaction among ferries significantly complicates the design problem; (3) development of two proactive routing schemes for data delivery in networks with mobile nodes. We study another approach for network capacity enhancement by deploying new nodes called throwboxes. Throwboxes are small and inexpensive devices equipped with wireless interfaces and storage. By relaying data between mobile nodes, throwboxes are able to create data transfer opportunities that otherwise would not exist. We systematically investigate two inter-related issues: throwbox deployment and routing, and develop algorithms for various deployment and routing approaches. Based on an extensive evaluation of these algorithms, we obtain several findings to guide the design and operation of throwbox-augmented DTNs. To address the issue of efficient and robust data delivery, we focus on DTN multicasting. Given the unique characteristics of DTNs, traditional solutions such as IP multicast can not be simply ported to DTNs. We identify the limitations of IP multicast semantics in DTNs and define new semantic models for DTN multicast. Based on these semantic models, We develop and evaluate several multicast routing algorithms with different routing strategies.
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关键词
intermittent connectivity,robust data delivery,mobile node,message ferry route,message ferry,delay tolerant network,data delivery,network design,throwbox-augmented DTNs,DTN multicast,relaying data,stationary node
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