Sommes-nous surveillés ? : entretien avec David Simplot-Ryl, propos recueillis par Dominique Chouchan

National audienceL'identification par radiofréquence (RFID) déclenche des craintes dont certaines résulteraient d'une surestimation des risques engendrés par les usages envisagés à ce jour

A Novel Family of Geometric Planar Graphs for Wireless Ad Hoc Networks

International audienceWe propose a radically new family of geometric graphs, i.e., Hypocomb, Reduced Hypocomb and Local Hypocomb. The first two are extracted from a complete graph; the last is extracted from a Unit Disk Graph (UDG). We analytically study their properties including connectivity, planarity and degree bound. All these graphs are connected (provided the original graph is connected) planar. Hypocomb has unbounded degree while Reduced Hypocomb and Local Hypocomb have maximum degree 6 and 8, respectively. To our knowledge, Local Hypocomb is the first strictly-localized, degree-bounded planar graph computed using merely 1-hop neighbor position information. We present a construction algorithm for these graphs and analyze its time complexity. Hypocomb family graphs are promising for wireless ad hoc networking. We report our numerical results on their average degree and their impact on FACE routing. We discuss their potential applications and some open problems

Mobile-Beacon Assisted Sensor Localization with Dynamic Beacon Mobility Scheduling

International audienceIn mobile-beacon assisted sensor localization, beacon mobility scheduling aims to determine the best beacon trajectory so that each sensor receives sufficient beacon signals with minimum delay. We propose a novel DeteRministic bEAcon Mobility Scheduling (DREAMS) algorithm, without requiring any prior knowledge of the sensory field. In this algorithm, beacon trajectory is defined as the track of depth-first traversal (DFT) of the network graph, thus deterministic. The mobile beacon performs DFT under the instruction of nearby sensors on the fly. It moves from sensor to sensor in an intelligent heuristic manner according to RSS (Received Signal Strength)-based distance measurements. We prove that DREAMS guarantees full localization (every sensor is localized) when the measurements are noise-free. Then we suggest to apply node elimination and topology control (Local Minimum Spanning Tree) to shorten beacon tour and reduce delay. Through simulation we show that DREAMS guarantees full localization even with noisy distance measurements. We evaluate its performance on localization delay and communication overhead in comparison with a previously proposed static path based scheduling method

Planarisation de graphes dans les réseaux ad-hoc

We propose a radically new family of geometric graphs, i.e., Hypocomb, Reduced Hypocomb and Local Hypocomb. The first two are extracted from a complete graph; the last is extracted from a Unit Disk Graph (UDG). We analytically study their properties including connectivity, planarity and degree bound. All these graphs are connected (provided the original graph is connected) planar. Hypocomb has unbounded degree while Reduced Hypocomb and Local Hypocomb have maximum degree 6 and 8, respectively. To our knowledge, Local Hypocomb is the first strictly-localized, degree-bounded planar graph computed using merely 1-hop neighbor position information. We present a construction algorithm for these graphs and analyze its time complexity. Hypocomb family graphs are promising for wireless ad hoc networking. We report our numerical results on their average degree and their impact on FACE routing. We discuss their potential applications and pinpoint some interesting open problems for future research

Mobile Sensor Deployment with Connectivity Guarantee

In this paper, we consider the self-deployment of wireless sensor network. We present a deployment strategy for mobile wireless sensor network which maximizes the sensors covered area with the constraint that the resulting deployment provides a connected topology. Our deployment algorithm is distributed and is based on subset of neighbour for motion decision. Each node is considered as a particle and its movements are governed by the interaction with a part of its neighboring nodes. The interacting neighbors and the node's direction are chosen based on the local relative neighborhood graph. Analytical and simulations results show that the resulting graph is connected, the distance between two sensors is maximized and thus the area covered is maximized. We also show by extensive simulation that some simple modifications of our algorithm allow different coverage schemes such as Point of Interest coverage and barrier coverage

Connectivity Preservation and Coverage Schemes for Wireless Sensor Networks

International audienceIn this paper, we consider the self-deployment of wireless sensor networks. We present a mechanism which allows to preserve network connectivity during the deployment of mobile wireless sensors. Our algorithm is localized and is based on a subset of neighbors for motion decision. Our algorithm maintains a connected topology regardless of the direction chosen by each sensor. To preserve connectivity, the distance covered by the mobile nodes is constrained by the connectivity of the node to its neighbors in a connected subgraph like the relative neighborhood graph (RNG). We show the connectivity preservation property of our algorithm through analysis and present some simulation results on different deployment schemes such as full coverage, point of interest coverage or barrier coverage

Poster: Modèlisation de protocoles MAC pour réseaux de capteurs à l'aide de chaînes de Markov

La conception d'une pile de communication pour une application pour réseaux de capteurs est fastidieuse. En effet, il faut déterminer les protocoles les plus aptes à convenir à cette application bien particulière. Il faut donc disposer d'un moyen pour les comparer en tenant compte des caractèristiques de l'application et de ses besoins. Nous proposons une méthode permettant d'évaluer les performances d'un protocole MAC dans un réseau donné et en fonction du trafic généré par l'application. Cette analyse s'appuie sur l'utilisation des chaînes de Markov à temps discret. Cette méthode offre une séparation claire entre le comportement du protocole et la topologie étudiée, permettant ensuite de les réutiliser pour former d'autres scénarios

Localized Broadcast Incremental Power Protocol for Wireless Ad Hoc Networks.

As broadcasting is widely used for miscellaneous maintenance operations in wireless ad hoc networks, where energy is a scarce resource, an efficient broadcasting protocol is of prime importance. One of the best known algorithm, named BIP (Broadcast Incremental Power), constructs a spanning tree rooted at a given node. This protocol offers very good results in terms of energy savings, but its computation is unfortunately centralized, as the source node needs to know the entire topology of the network to compute the tree. Many localized protocols have since been proposed, but none of them has ever reached the performances of BIP. Even distributed versions of the latter have been proposed, but they require a huge transmission overhead for information exchange and thus waste energy savings obtained thanks to the efficiency of the tree. In this paper, we propose and analyze a localized version of this protocol. In our method, each node is aware of the position of all the hosts in the set of its 2-hop neighborhood and compute the BIP tree on this set, based on information provided by the node from which it got the packet. That is, a tree is incrementally built thanks to information passed from node to node in the broadcast packet. Only the source node computes an initially empty tree to initiate the process. We also provide experimental results showing that this new protocol has performances very close to other good ones for low densities, and is very energy-efficient for higher densities with performances that equal the ones of BIP

Algorithmes pour l'estimation des données dans les réseaux de capteurs

International audienceLa collecte des données est un des enjeux majeurs dans les réseaux de capteurs. En effet, les communications induites par la transmission de données réduisent considérablement la durée de vie du réseau. Une des techniques utilisées pour réduire la quantité de données transférées est l'agrégation et selon le type des données étudiées, une des possibilités est l'utilisation de série temporelle ARMA. Dans cet article, nous proposons quatre algorithmes d'agrégation de données s'appuyant sur le modèle AR permettant ainsi la diminution de la consommation d'énergie dans les réseaux de capteurs et augmentant la durée de vie de ceux-ci

From the Internet of things to the Internet of physical world

International audienceThis article describes the different kinds of RFID tags. It details passive and active RFID tags different functions and uses