A Representative and Accurate Characterization of Inter-contact Times in Mobile Opportunistic Networks

© ACM 2013. This is the author's version of the work. It is posted here for your personal use. Not for redistribution. The definitive Version of Record was published in MSWiM '13 Proceedings of the 16th ACM international conference on Modeling, analysis & simulation of wireless and mobile systems; http://dx.doi.org/10.1145/2507924.2507936.A representative characterisation of inter-contact times between nodes is essential for the performance evaluation of mobile networks. The most common characterization of inter-contact times is based on the study of the aggregate distribution of contacts between individual pairs of nodes. The problem with this aggregate distribution is that it is not always representative of the individual pair distributions, especially in the short term and when the number of nodes in the network is high. Thus, deriving results from this characterisation, can lead to inaccurate performance evaluations results. In this paper, we propose and evaluate two new methods for characterising the inter-contact times distribution in mobile networks. We prove that these characterizations have a higher representativeness, thereby improving the accuracy of the derived performance results. For evaluating the precision of the different characterizations we use the epidemic routing protocol, which has an analytical performance expression that is based on a contact rate λ. We derive from each of the characterizations the corresponding λ values. Then, we compare the results obtained using the analytical expression with simulation results using both synthetic and real contact traces. It is shown that the new characterization methods are very accurate, even for reduced contact traces and high number of nodes.This work was partially supported by the Ministerio de Ciencia e Innovación, Spain, under Grant TIN2011-27543-C03-01.Hernández Orallo, E.; Cano Escribá, JC.; Tavares De Araujo Cesariny Calafate, CM.; Manzoni, P. (2013). A Representative and Accurate Characterization of Inter-contact Times in Mobile Opportunistic Networks. ACM. https://doi.org/10.1145/2507924.2507936

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New approaches for characterizing inter-contact times in opportunistic networks

Characterizing the contacts between nodes is of utmost importance when evaluating mobile opportunistic networks. The most common characterization of inter-contact times is based on the study of the aggregate distribution of contacts between individual pairs of nodes, assuming an homogenous network, where contact patterns between nodes are similar. The problem with this aggregate distribution is that it is not always representative of the individual pair distributions, especially in the short term and when the number of nodes in the network is high. Thus, deriving results from this characterization can lead to inaccurate performance evaluation results. In this paper, we propose new approaches to characterize the inter-contact times distribution having a higher representativeness and, thus, increasing the accuracy of the derived performance results. Furthermore, these new characterizations require only a moderate number of contacts in order to be representative, thereby allowing to perform a temporal modelization of traffic traces. This a key issue for increasing accuracy, since real-traces can have a high variability in terms of contact patterns along time. The experiments show that the new characterizations, compared with the established one, are more precise, even using short time contact traces. © 2016 Elsevier B.V. All rights reserved.Hernández Orallo, E.; Cano Escribá, JC.; Tavares De Araujo Cesariny Calafate, CM.; Manzoni, P. (2016). New approaches for characterizing inter-contact times in opportunistic networks. Ad Hoc Networks. 52:160-172. doi:10.1016/j.adhoc.2016.04.003S1601725

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Hybrid Satellite-Terrestrial Communication Networks for the Maritime Internet of Things: Key Technologies, Opportunities, and Challenges

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The increasing popularity of some new mobile technologies (smartphones for example) has opened new interesting scenarios in communications because of the possibility of a device to communicate with another one without using the wireless (or wired) network interfaces but taking advantages of the mobility of all the devices. In this direction, one of the most important evolution of Mobile ad hoc networks are opportunistic networks, that are self-organizing networks where there are not any guarantee of two devices to be linked with complete multi-hop path in any time. What a node has to do to deliver a certain message, is to nd a space-time multi-hop path, that is portions of path that can carry on the message during the time until it reaches the destination. We can see an example in Figure 1: the source S has to deliver a message to the destination D; the message can arrive at D at time t3, even if in [t1,t3] S and D are not directly linked. As nodes do not have any knowledges of the network topology, but only of the destination the massage have to arrive to, this way of delivering needs at any time to make some decisions, that are to whom has to be sent message and how many copies has to be sent