Claude Chaudet

• Ph.D (Computer Science, 2004)
• Software Engineer at University of Geneva

Wireless sensor networks represent a promising solution for forest fire detection. Yet, these networks are composed of constrained elements and their operation must be optimized to reach a satisfying performance in terms of response time, fault tolerance and network lifetime. Studies have been made in this direction but they have studied only some...

This paper examines the role played by malevolent linguistic creativity in the generation and maintenance of anti-immigration communities on Twitter. In order to understand this phenomenon, we combined data science and qualitative techniques for the analysis of 112,789 pro- and anti-immigration tweets with a focus on their hashtags. Our analysis po...

In the fast-growing Internet of Things (IoT)[...].

Wireless Body Area Networks (WBAN) is a recent challenging area in the health monitoring domain. There are several concerns in this area ranging from energy efficient communication to designing delays efficient protocols that support nodes dynamicity induced by human body mobility. This paper focuses on the convergecast or data gathering protocols...

The rapid advances in sensors and ultra-low power wireless communication has enabled a new generation of wireless sensor networks: Wireless Body Area Networks (WBAN). To the best of our knowledge the current paper is the first to address broadcast in WBAN. We first analyze several broadcast strategies inspired from the area of Delay Tolerant Networ...

The rapid advances in sensors and ultra-low power wireless communication has enabled a new generation of wireless sensor networks: Wireless Body Area Networks (WBAN). To the best of our knowledge the current paper is the first to address broadcast in WBAN. We first analyze several broadcast strategies inspired from the area of Delay Tolerant Networ...

In a near future, wireless networks will be one of the key technologies for road traffic management in smart cities. Vehicles and dedicated roadside units should be interconnected through wireless technologies such as IEEE 802.11p (WAVE). Traffic light and road signs may also take their place in this architecture, forming a large-scale network of s...

Advances in wearable and implementable of wireless sensors have enable the development of tiny and intelligent sensors called body sensors. Monitoring the vital body parameters in real-time using wireless body area network (WBAN) has shown great potential in improving healthcare quality not only for patients but also for medical staff. However, sec...

Les progrès rapides des capteurs et de la communication sans fil à ultra-faible puissance ont permis a une nouvelle génération de réseaux de capteurs sans fil de voir le jour : Wireless Body Area Networks (WBAN). Nous commençons d'abord par l'analyse de plusieurs stratégies de diffusion inspirées des réseaux tolérants au délai (DTN : Delay Tolerant...

-Wireless body area network(WBAN) has shown great potential in improving healthcare quality not only for patients but also for medical staff. However, security and privacy are still an important issue in WBANs especially in multi-hop architectures. In this paper, we propose and present the design and the evaluation of a secure lightweight and energ...

The rapid advances in sensors and ultra-low power wireless communication has enabled a new generation of wireless sensor networks: Wireless Body Area Networks (WBAN). To the best of our knowledge the current paper is the first to address broadcast in WBAN. We first analyze several broadcast strategies inspired from the area of Delay Tolerant Networ...

Recent advances in the field of intelligent transportation systems have focused on the use of wireless networks to link vehicles and road infrastructure. Applications that might result from such networks range from the adaptive management of traffic lights to the detection of traffic jams and accidents. Whatever the case may be, it seems important...

Time-based localization in Wireless Body Area Networks (WBANs), has attracted growing research interest for the last past years. Nodes positions can be estimated based on peer-to-peer radio transactions between devices. Indeed, the accuracy of the localization process could be highly affected by different factors, such as the WBAN channels where th...

The applications of Wireless Body Area Networks (WBANs) encompass several uses such as home activity monitoring , postural rehabilitation, or sportive gesture recording, which require motion capture. Such motion capture can be realized by acquiring the positions of on-body nodes, which can be deduced from device-to-device distance measurements. In...

Software Defined Networking (SDN) is a network paradigm that relies on the separation of the control and forwarding planes in IP networks. The interconnection devices take forwarding decisions solely based on a set of multi-criteria policy rules defined by external applications called controllers. It is possible to let multiple controllers manage e...

In the context of radiolocation in Wireless Body Area Networks (WBANs), nodes positions can be estimated through time-based ranging algorithms. For instance, the dis-tance separating a couple of nodes can be estimated accurately by measuring the Round Trip Time of Flight of an Impulse Radio Ultra Wideband (IR-UWB) link. This measure usually relies...

This paper presents the latest advances in our research work focused on VIRMANEL and SILUMOD, a couple of tools developed for research in wireless mobile multihop networks. SILUMOD is a domain specific language dedicated to the definition of mobility models. This language contains key- words and special operators that make it easy to define a mobil...

In this paper, we account for radio-location exper-iments aiming at both indoor navigation and mobility detection applications for Wireless Body Area Networks (WBAN). This measurement campaign involved IEEE 802.15.4-compliant inte-grated radio devices organized within a full mesh topology over on-body and off-body links. The latter devices produce...

This paper addresses the problem of navigation in cooperative groups of Wireless Body Area Networks. On-body radio devices determine their position by estimating their distance to other nodes from the measurement of the Round Trip Time Of Flight of Impulse Radio-Ultra Wideband signals. The nodes not only measure their distance to fixed anchors, but...

The energy consumed by communication networks can be reduced in several ways. For example, concentrating the workload of an infrastructure on a reduced set of devices, while switching off the others, is called resource consolidation. It is particularly suited to routing of data traffic when a network is lightly loaded, but the selection of the rout...

In this paper, we propose and evaluate an algorithm and a few variations to exclude aberrant landmarks before performing a maximum likelihood estimator in order to evaluate a mobile node position in a 1 hop indoor wireless network more accurately. We exclude data coming from landmarks based on a global likelihood to alleviate the effects of multipa...

In this paper, we describe and enhance TAPIOCA (distribuTed and AdaPtive IntersectiOns Control Algorithm), a distributed algorithm that relies on a wireless sensor network to manage urban road traffic efficiently. We detail TAPIOCA with a special emphasis on communications and we study its reaction to losses and delays induced by the use of wireles...

Software Defined Networking (SDN) is a network paradigm that relies on the separation of the control and forwarding planes in IP networks. The interconnection devices take forwarding decisions solely based on a set of multi-criteria policy rules defined by external applications called controllers. It is possible to let multiple controllers manage e...

Wireless Sensor Networks (WSN) users often use simulation campaigns before real deployment to evaluate performance and to fine-tune application and network parameters. This process requires repeating the same experiments under similar conditions and to collect, parse and present data efficiently. This chapter introduces MakeSense: A tool that autom...

This paper presents and evaluates a method to localize devices that communicate using a wireless network. The distances that separate a blind node, willing to determine its position, and a set of anchor nodes, that know their locations, are evaluated using the signal attenuation (RSSI) measured on data packets. However, multipath effects, frequent...

This paper presents a summary of the key results obtained within the “SINARI” project; a French collaborative research project which focuses on developing methods for assessing the dependability and cyber security of the coupled infrastructure made up by the electrical distribution network and its supporting information system and telecommunication...

In this paper, we present ARMATURE, a peer-to-peer overlay that provides highly resilient communication service for critical infrastructure control. ARMATURE can encapsulate all control traffic, e.g. SCADA sessions, within secure and highly resilient transport tunnels. Herein, it does not rely on any particular ISP provisions and can use any availa...

In this article, we detail and evaluate a distributed algorithm that defines the green lights sequence and duration in a multi-intersection intelligent transportation system (ITS). We expose the architecture of a wireless network of sensors deployed at intersections, which takes local decisions without the help of a central entity. We define an ada...

Dans cet article, nous étudions le scénario consistant à utiliser un réseau de capteurs sans fil afin de contrôler les feux de circulation d'un réseau de transport urbain et d'optimiser son fonctionnement en réduisant le temps moyen d'attente des usagers. Le faible coût des capteurs autorisant un nombre de points de mesure important, il est possibl...

In this article, we introduce VIRMANEL a tool we developed to establish an environment for the study of multihop mobile networks. VIRMANEL is a tool that manages virtual machines corresponding to mobile nodes, emulates their movements and the resulting disconnections. It features a GUI to observe the behavior of mobile nodes. Nodes mobility is spec...

Positioning a device with the only help of an RF transmitter in an indoor environment is difficult because of the complexity and of the unpredictable nature of radio propagation in such a scenario. The effects of fading, multipath, shadowing make it difficult to infer distance between two points from a blind measurement of the signal attenuation. H...

In this paper, we address the problem of controlling traffic lights at an intersection with a spatially distributed sensor network. We propose a sensor network architecture that does not depend on a centralized coordinator and we separate logically it into 4 levels of hierarchy. On this architecture, we define and evaluate through simulations an ad...

This paper describes VIRMANEL, a new, open source (LGPL) tool that we developed to run experiments and evaluate protocols and algorithms on mobile multihop networks using real software and real operating systems. VIRMANEL comprises an integrated domain-specific language to define new mobility models, a Graphical User Interface to study the behavior...

In this paper we examine how to efficiently build a brokers overlay to implement publish/subscribe in a wireless sensor network, trying to reduce sensor nodes energy consumption, memory required for buffering packets and delivery time. We evaluate, on the connectivity graph that represents the network, the performance of various criteria that can b...

The energy consumption of network devices, and, as a consequence, of communication networks, is generally independent from their level of utilization, which results in a waste of energy when the network is lightly loaded. Ideally the consumption of a network should be proportional to the amount of traffic it conveys. The most straightforward way to...

In this demonstration, we show how to use a couple of tools we developed, VIRMANEL and SIMULOD, to study how the true implementation of an ad hoc routing protocol behaves under various mobility scenarios. VIRMANEL is a tool that configure virtual machines connections with respect to mobility. It features a GUI to observe the behavior of mobile node...

Indoor localization has been the subject of many studies and still remains a very difficult issue due to the presence of multiple paths, fading, shadowing and timely variations in the environment. This paper studies the use of the Received Signal Strength Indicator (RSSI) metric for range estimation in a wireless sensor network. We perform experime...

Le trafic routier urbain est au cœur de nombreuses problématiques : plus encore ces dernières années, cet aspect critique intervenant au quotidien est défavorable à de nombreux domaines, tels que l'économie ou encore l'écologie. Pour ces raisons, les systèmes de transport intelligents (STI) sont apparus depuis la fin des années 1990, permettant d'o...

Reduction of unnecessary energy consumption is becoming a major concern in wired networking, because of the potential economical benefits and of its expected environmental impact. These issues, usually referred to as "green networking", relate to embedding energy-awareness in the design, in the devices and in the protocols of networks. In this work...

In this article, we propose a model to compare strategies to deploy a multiple brokers overlay to support a publish/subscribe middleware in wireless sensor networks. We provide expressions for the expected memory size required for buffering packets and the energy consumption at each node and evaluate how many brokers are necessary in a scenario and...

p>L'IEEE a introduit, en 2005, une extension à la norme IEEE 802.11 afin de prendre en charge la différentiation de services au niveau de l'accès au médium dans des réseaux locaux sans-fil. Cet amendement définit quatre classes de trafic et fournit les mécanismes permettant d'y associer quatre niveaux de priorités distincts. Dans cet article, nous...

This extended abstract overviews some of the advantages and problems to overcome when implementing a publish/subscribe system over a wireless sensor network. Publish/subscribe usually relies on a set of intermediate nodes, brokers that gather and dispatch all the packets emissions. The presence of these brokers lightens the duty of most regular nod...

La modélisation des infrastructures critiques interdépendantes est un outil précieux pour l'identification de leurs modes de défaillance les plus critiques et d'en trouver des parades. Différentes approches ont déjà été utilisées pour modéliser les infrastructures critiques ainsi que leurs interdépendances en vue de leur sécurisation. Elles permett...

The energy consumed by communication networks can be reduced in several ways. A promising technique consists in concentrating the workload of an infrastructure on a reduced set of devices, while switching off the others. This technique, called "resource consolidation", is particularly appealing when routing data traffic over a lightly loaded networ...

Abstract— In this work, we analyze the design of green routing algorithms and evaluate the achievable energy savings that such mechanisms could allow in several realistic network scenarios. We formulate the problem as a minimum energy routing optimization, which we numerically solve considering a core-network scenario, which can be seen as a worst-...

The meaning of the terms “security” and “safety” varies considerably from one context to another, leading to potential ambiguities. These ambiguities are very problematic in the critical infrastructure protection domain, which involves multiple actors and engineering disciplines. Avoiding misunderstandings caused by the ambiguities during the early...

This article presents a method to generate conjointly topological graphs representing interdependent telecommunication and power networks. The method proposes to use a single basis, possibly random, as the common input of independent graph generation algorithms, allowing to apply different rules for different networks while preserving dependencies...

Variable preamble sampling is a technique used for accessing the medium in low-power constrained networks such as wireless sensor networks. We provide an optimal bound for power consumption in preamble sampling techniques, and we present a model of this technique as a function of power consumption and time of radio utilization. We compare our model...

This article aims at a finer apprehension of the relations between safety and security, which are intrinsically and increasingly intricate. We introduce a new conceptual framework to better capture their moving perimeters. Then, we present our on-going work to characterize safety and security interactions, varying from reinforcement to strong antag...

Wireless sensor networks (WSN) are characterized by stringent power constraints. Researchers focus on improving their power efficiency in order to allow building up networks that survive for long periods of time on limited battery resources without any human intervention. Improvements have been proposed for every hardware and software component, in...

Due to the increasing demand in services' quality and the growing concerns about external threats, the protection of critical infrastructures has recently become a major concern. In this article, we study the potential effect of interdependencies that may occur between two of these infrastructures: the telecommunication networks and the electrical...

Since 2005, IEEE 802.11-based networks are able to provide a certain level of Quality of Service by the means of service differentiation, thanks to the IEEE 802.11e amendment. However, no mechanism or method has been standardized to accurately evaluate the amount of resources remaining on a given channel. Such evaluation would however be a good ass...

This paper presents a survey on transport and routing protocols for wireless sensor networks (WSN). Research challenges regarding the problem of end-to-end reliability are addressed in particular.

We propose a new technique to estimate the bandwidth available to wireless nodes and by extension on one-hop links in IEEE 802.11-based ad hoc networks. Our technique exploits the fact that a node can estimate the channel occupancy by monitoring its environment. It provides a non-intrusive estimation meaning that it does not generate any additional...

RÉSUMÉ. Dans cet article, nous proposons un état des lieux sur la qualité de service dans les réseaux ad hoc telle que nous la percevons actuellement. Après une discussion sur les perfor-mances des réseaux ad hoc en termes de bande passante, délai et taux de pertes, nous apportons un point de vue critique sur certaines solutions de qualité de servi...

In this article, we propose a method to enhance accuracy of the available bandwidth estimation in IEEE 802.11-based ad hoc networks. This method combines medium state monitoring, probability of collision estimation and backoff time evaluation, improving the method described in C. Sarr et al., (2005). We evaluate our solution by simulation on differ...

Positioning systems in self-organizing networks generally rely on measurements such as delay and received signal strength, which may be difficult to obtain and often require dedicated equipment. An alternative to such approaches is to use simple connectivity information, that is, the presence or absence of a link between any pair of nodes, and to e...

Abstract The IEEE 802.11 MAC layer is known,for its low performances,in wireless ad hoc networks. For instance, it was shown in the litterature that two independent emitters nodes can easily mo- nopolize the medium, preventing other nodes to send packets. The protocol we introduce in this article is a simple variation of the original 802.11 MAC lay...

Network measurement is essential for assessing performance issues, identifying and locating problems. Two common strategies are the passive approach that attaches specific devices to links in order to monitor the traffic that passes through the network and the active approach that generates explicit control packets in the network for measurements....

This paper proposes a distributed and topology-independent contention control mechanism for IEEE 802.11-based multi-hop ad hoc networks, which aims at ensuring per-station fairness without degrading the total network throughput, and without requiring any information exchange between the nodes. The proposed algorithm dynamically controls the frequen...

We propose a new technique to estimate the available bandwidth of wireless nodes and by extension of one-hop links in IEEE 802.11-based ad hoc networks. Our technique exploits the fact that a node can estimate the channel occupancy by monitoring its environment. It provides a non-intrusive estimation meaning that it doesn't generate additional traf...

Although 802.11 is initially designed for infrastructure based networks, the Distributed Coordination Function (DCF) provided in 802.11 allows mobiles to access the radio medium without the need of a base station. Thus, studies in wireless multi-hops networks, also called ad hoc networks often rely on the use of the IEEE 802.11 standard for the phy...

The IEEE 802.11 MAC layer is known for its low performances in wireless ad hoc networks. For instance, it has been shown in the literature that two independent emitters nodes can easily monopolize the medium, preventing other nodes to send packets. The protocol we introduce in this article is a simple variation of the original IEEE 802.11 MAC layer...

Afin d'obtenir les informations nécessaires à une bonne gestion des ressources de leur réseau, les opérateurs placent des sondes passives sur les liens de leurs points de présence. Dans cet article, nous donnons des écritures en programmes linéaires mixtes des problèmes de placement de sondes simples ou avec échantillonnage, et donnons une stratégi...

In [C. Chaudet et al., Feb. 2002], BRuIT, a bandwidth reservation protocol for ad hoc networks that takes into account the influence of distant emitters on medium availability, has been described in broad outline. This article presents enhancements and evaluations of BRuIT. We justify the choices made in BRuIT, especially on the range of available...

Les recherches menées dans le domaine de la QoS pour les réseaux ad hoc ont connu un essor ces dernières années. La principale difficulté lors de la mise en place d'un protocole de QoS, réside dans l'estimation précise des ressources disponibles. Dans cet article, nous proposons une méthode fiable permettant d'estimer la bande passante résiduelle s...

In this paper, we experiment different ad hoc configurations that have been pointed out in the literature for presenting some performance problems with IEEE 802.11 MAC protocol. We focus on fairness issues and show that some problems identified by simulation are real and should be considered while others are softened and some are even nonexistent d...

Hybrid networks composed of a wireless infrastructure network providing Internet access to an underlying ad hoc network are more and more attractive due to their low installation cost. In these all-wireless environments, performance is a key issue as radio bandwidth is scarce. Handoffs management is particularly important as these networks are like...

Hybrid networks composed of a wireless infrastructure network providing Internet access to an underlying ad hoc network are more and more attractive due to their low installation cost. In these all-wireless environments, performance is a key issue as radio bandwidth is scarce. Handoffs management is particularly important as these networks are like...

Wireless networks are a real commercial success nowadays. There is an increasing number of solutions based on the IEEE 802.11 (Wi-Fi) standard. Usually, these networks require a base station to transmit frames between mobiles. Mobile ad hoc networks are mobile, spontaneous and autonomous wireless networks. Nodes communicate directly without requiri...

This article presents a theoretical modeling of a small but basic scenario that shows a great inequity in medium access between nodes using the IEEE 802.11 DCF mode. In this configuration, two terminals evolve independently and are almost never synchronized, which results in a serious performance issue for a third emitter in between. The results ar...

Les réseaux ad hoc sont des réseaux sans fil, mobiles et sans infrastructure fixe. Compte tenu de son large succès commercial la norme IEEE 802.11 initialement destinée à des réseaux sans fil avec infrastructure est actuellement la plus utilisée pour constituer de tels réseaux. Cette thèse explore les problématiques de réservation de bande passante...

In this paper we present a bandwidth reservation protocol called BRuIT designed to operate in mobile ad hoc networks. The protocol is provided together with a policy-based outsourcing model enabling context-aware reservation authorization.

L'engouement suscité par la téléphonie cellulaire laisse à penser que l'utilisateur va devenir de plus en plus mobile. Les réseaux ad-hoc répondent à ce besoin en éliminant le besoin d'infrastructure fixe pour communiquer. L'activité du groupe IETF Manet créé en 1996 montre que le développement de ces réseaux sans fil et sans infrastructure est en...

This article presents a theoretical modeling of an ad hoc network scenario that shows that a great inequity can appear in medium access between nodes using the IEEE 802.11 DCF mode. Numerical results confirm that both asynchronism and Extended Inter Frame Spacing (EIFS) use perturbate the equity between mobiles in wireless networks.