The ability of a node to relay information in a network is often measured using betweenness centrality. In order to take into account the fact that the role of the nodes vary through time, several adaptations of this concept have been proposed to timeevolving networks. However, these definitions are demanding in terms of computational cost, as they call for the computation of time-ordered paths. We propose a definition of centrality in link streams which is node-centric, in the sense that we only take into account the direct neighbors of a node to compute its centrality. This restriction allows to carry out the computation in a shorter time compared to a case where any couple of nodes in the network should be considered. Tests on empirical data show that this measure is relatively highly correlated to the number of times a node would relay information in a flooding process. We suggest that this is a good indication that this measurement can be of use in practical contexts where a node has a limited knowledge of its environment, such as routing protocols in delay tolerant networks.
In the aftermath of a natural or industrial disaster, locating individuals is crucial. However, disasters can cause extensive damage to the network infrastructures and a generalized loss of communication among survivors. In this article, we present a network support solution that provides a post-disaster geolocation-collecting service that relies on inter mobile device connections. On top of this dynamically built network, survivors' mobile devices exchange information about geolocation of others they have encountered. Such information is routed towards predefined data collection centers using either the DTN Epidemic or Spray and Wait DTN protocol. Experiments were conducted on the ONE simulator and performance evaluation results confirm the effectiveness of our proposal.
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