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Réseaux ad hoc aidés par satellites pour les communications d'urgence

Abstract : The services offered by traditional wireless systems such as cellular networks depend on established infrastructures. In the aftermath of a disaster, communication infrastructures may be totally destroyed. Therefore, there is a need for mobile technologies being independent of infrastructure where network management is the result of cooperation among terminals. Ad hoc networks are a promising technology for emergency communications requiring easily deployable and dynamically adaptable topologies. However, ad hoc networks can experience severe impairments because of node motion in the case of Mobile Ad hoc NETworks (MANETs) or scarce node density in the case of Wireless Mesh Networks (WMNs). We first consider a scenario of forest fire fighting operations where the nodes form a MANET. Due to node mobility, network partitioning may occur. The network is then split into unconnected groups. The limited availability of communications in this situation compromises the rescue and recovery operations. Satellites may help in this respect by setting up temporary back up links and bridging the unconnected islands. We particularly study the problem of selecting nodes that will provide access to the satellite capacity (i.e. gateway nodes). A key challenge in this scenario is that nodes are mobile resulting in topology changes. We address this challenge by extending the use of the clustering techniques initially designed to solve scalability issues in MANETs. K-hop clustering techniques allow to form virtual groups called clusters and to select particular nodes called clusterheads providing access to the satellite communication. Applying this technique to our scenario raises two problems: the node mobility modeling and the cluster structure maintenance. For the first problem, we compare a specific topology model, FireMobility to two generic topology models: Random Walk and Reference Region Group Mobility model. We show the importance of including dedicated behavioral patterns to represent the actual field activity and its impact on the accuracy of the simulation results. For the cluster maintenance problem, we propose a new maintenance policy allowing to minimize the overhead in signaling, so as to save bandwidth and energy. Finally, we consider a scenario where the nodes form a WMN. Satellite links are set up to bridge the different parts of the network and to connect the disaster area with headquarters. For this scenario, we propose a selection procedure based on genetic algorithm.
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Submitted on : Thursday, July 19, 2012 - 2:40:56 PM
Last modification on : Wednesday, December 15, 2021 - 10:02:53 AM
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2012telb0227_Hamdi_Monia.pdf
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  • HAL Id : tel-00719303, version 1

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Monia Hamdi. Réseaux ad hoc aidés par satellites pour les communications d'urgence. Réseaux et télécommunications [cs.NI]. Télécom Bretagne, Université de Rennes 1, 2012. Français. ⟨NNT : ⟩. ⟨tel-00719303⟩

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