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See detailExploiting Resource Heterogeneity in DTN
Sandulescu, Gabriel UL; Schaffer, Peter UL; Nadjm-Tehrani, Simin UL

in Wireless Communications & Mobile Computing (2012), 13(3), 230-243

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See detailResource-Aware routing in delay and disruption tolerant networks
Sandulescu, Gabriel UL

Doctoral thesis (2011)

In recent years a new class of networks, known as delay- and disruption-tolerant networks (DTNs), have emerged with applications in vehicular communications, emergency response and the military, to ... [more ▼]

In recent years a new class of networks, known as delay- and disruption-tolerant networks (DTNs), have emerged with applications in vehicular communications, emergency response and the military, to mention a few. This thesis studies the resource-aware routing problem in DTNs along four lines. First, the thesis presents the design and comparative evaluation of a delay-tolerant routing protocol (ORWAR) which optimises message transmission and bandwidth usage during opportunistic encounters. This is done through the estimation of contact duration between nodes, selection of the most suitable message to forward at any contact opportunity, and message differentiation. Second, the thesis proposes a hybrid scheme whereby opportunistic and infrastructure-based communication can be combined to overcome network partitions and packet losses. Collaboration between two networks characterised by different capacities, costs, and performance levels has been shown to be not only cost-effective, but also capable of increasing network survivability in the combined network. Third, it proposes and evaluates a mathematical model that can be used to compute the optimal level of redundancy and replication of a routing protocol as a function of message characteristics. Fourth, a holistic approach to resources is proposed, where variations in the spatial and temporal distribution of various resources can feed strategies to reduce resource consumption. Using estimates of vicinity resources, a routing protocol may not only use up fewer resources overall, but may also consume resources preferentially from nodes with higher resource levels, sparing whenever possible those with limited supplies. [less ▲]

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See detailVicinity Resource Cartography for Delay-Tolerant Networks: a Holistic Perspective
Sandulescu, Gabriel UL; Schaffer, Peter UL; Nadjm-Tehrani, Simin UL

in 2010 IFIP W IRELESS D AYS (2010)

In this paper we propose a distributed algorithm allowing nodes in delay-tolerant networks to construct vicinity resource maps based on past encounters. Our algorithm estimates the availability of the ... [more ▼]

In this paper we propose a distributed algorithm allowing nodes in delay-tolerant networks to construct vicinity resource maps based on past encounters. Our algorithm estimates the availability of the following resources: energy, buffer space, and bandwidth. We then show how a store-carry-forward scheme may benefit from having access to these resource estimates. While knowledge about resources available in the vicinity allows nodes to implement meaningful custodian election strategies, an evaluation of available bandwidth and contact time allows them to carry out adaptive queue management strategies. Thus, such strategies can be approached from a holistic perspective based on the availability of the three resources under consideration in node proximity.We validate our model separately in time-varying and space-varying environments. In addition to synthetic mobility models (random waypoint) we validate our resource estimation in a disaster area mobility model (using Bonn motion traces). We show that by using this information a routing protocol may dramatically improve its delivery rate and energy overhead while keeping delivery latency almost constant. [less ▲]

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