1,046 research outputs found

    Recent Developments on Mobile Ad-Hoc Networks and Vehicular Ad-Hoc Networks

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    This book presents collective works published in the recent Special Issue (SI) entitled "Recent Developments on Mobile Ad-Hoc Networks and Vehicular Ad-Hoc Networks”. These works expose the readership to the latest solutions and techniques for MANETs and VANETs. They cover interesting topics such as power-aware optimization solutions for MANETs, data dissemination in VANETs, adaptive multi-hop broadcast schemes for VANETs, multi-metric routing protocols for VANETs, and incentive mechanisms to encourage the distribution of information in VANETs. The book demonstrates pioneering work in these fields, investigates novel solutions and methods, and discusses future trends in these field

    On the Relevance of Using Open Wireless Sensor Networks in Environment Monitoring

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    This paper revisits the problem of the readiness for field deployments of wireless sensor networks by assessing the relevance of using Open Hardware and Software motes for environment monitoring. We propose a new prototype wireless sensor network that fine-tunes SquidBee motes to improve the life-time and sensing performance of an environment monitoring system that measures temperature, humidity and luminosity. Building upon two outdoor sensing scenarios, we evaluate the performance of the newly proposed energy-aware prototype solution in terms of link quality when expressed by the Received Signal Strength, Packet Loss and the battery lifetime. The experimental results reveal the relevance of using the Open Hardware and Software motes when setting up outdoor wireless sensor networks

    Advancements in Wi-Fi-Based Passenger Counting and Crowd Monitoring: Techniques and Applications

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    The widespread use of personal mobile devices, including tablets and smartphones, created new opportunities for collecting comprehensive data on individual movements within cities while preserving their anonymity. Extensive research focused on turning personal mobile devices into tools for measuring human presence. To protect privacy, the data collected must be anonymous or pseudo-anonymous, leading to the preference for management data. A common approach involves analysing probe requests, which are Wi-Fi protocol messages transmitted by mobile devices while searching for access points. These messages contain media access control (MAC) addresses, which used to be unique identifiers. To safeguard the privacy of smartphone users, the major manufacturers (Google, Apple, and Microsoft) have implemented algorithms that generate random MAC addresses, which change often and unpredictably. This thesis focuses on the problem of fingerprinting Wi-Fi devices based on analysing management messages to overcome previous methods that relied on the MAC address and became obsolete. Detecting messages from the same source allows counting the devices in an area, calculating their permanence, and approximating these metrics with the ones of the humans carrying them. An open dataset of probe requests with labelled data has been designed, built, and used to validate the experiments. The dataset is also provided with guidelines for collecting new data and extending it. Since the dataset contains records of individual devices, the first step of this study was simulating the presence of multiple devices by aggregating multiple records in sets. Many experiments have been conducted to enhance the accuracy of the clustering. The proposed techniques exploit features extracted from individual management messages and from groups of messages called bursts. Moreover, other experiments show what happens when one or more features are split into their components or when the logarithm of their value is used. Before running the algorithm, a feature selection was performed and exploited to improve the accuracy. The clustering methods considered are DBSCAN and OPTICS

    Efficient Broadcasting for a Mobile Ad-hoc Network based Peer-to-peer Community Radio Service

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    Ad-hoc networks consisting entirely of simple mobile phones can be used to deploy village level telephony. We investigate a novel application for such networks – a peer-to peer community radio service. We envision a system, where any user in the network is equally empowered to generate and distribute audio content to the entire network, using his or her mobile phone. This study concentrates on a critical aspect of this service – the choice of the network-wide broadcast protocol. Using extensive simulations, we evaluate the suitability of various broadcast techniques for a rural peer-to-peer mobile adhoc network. Our simulations identify the best choice of protocols under various village network conditions while simultaneously identifying limitations of the current protocols.

    Reliable Message Dissemination in Mobile Vehicular Networks

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    Les rĂ©seaux vĂ©hiculaires accueillent une multitude d’applications d’info-divertissement et de sĂ©curitĂ©. Les applications de sĂ©curitĂ© visent Ă  amĂ©liorer la sĂ©curitĂ© sur les routes (Ă©viter les accidents), tandis que les applications d’info-divertissement visent Ă  amĂ©liorer l'expĂ©rience des passagers. Les applications de sĂ©curitĂ© ont des exigences rigides en termes de dĂ©lais et de fiabilitĂ© ; en effet, la diffusion des messages d’urgence (envoyĂ©s par un vĂ©hicule/Ă©metteur) devrait ĂȘtre fiable et rapide. Notons que, pour diffuser des informations sur une zone de taille plus grande que celle couverte par la portĂ©e de transmission d’un Ă©metteur, il est nĂ©cessaire d’utiliser un mĂ©canisme de transmission multi-sauts. De nombreuses approches ont Ă©tĂ© proposĂ©es pour assurer la fiabilitĂ© et le dĂ©lai des dites applications. Toutefois, ces mĂ©thodes prĂ©sentent plusieurs lacunes. Cette thĂšse, nous proposons trois contributions. La premiĂšre contribution aborde la question de la diffusion fiable des messages d’urgence. A cet Ă©gard, un nouveau schĂ©ma, appelĂ© REMD, a Ă©tĂ© proposĂ©. Ce schĂ©ma utilise la rĂ©pĂ©tition de message pour offrir une fiabilitĂ© garantie, Ă  chaque saut, tout en assurant un court dĂ©lai. REMD calcule un nombre optimal de rĂ©pĂ©titions en se basant sur l’estimation de la qualitĂ© de rĂ©ception de lien dans plusieurs locations (appelĂ©es cellules) Ă  l’intĂ©rieur de la zone couverte par la portĂ©e de transmission de l’émetteur. REMD suppose que les qualitĂ©s de rĂ©ception de lien des cellules adjacentes sont indĂ©pendantes. Il sĂ©lectionne, Ă©galement, un nombre de vĂ©hicules, appelĂ©s relais, qui coopĂšrent dans le contexte de la rĂ©pĂ©tition du message d’urgence pour assurer la fiabilitĂ© en multi-sauts. La deuxiĂšme contribution, appelĂ©e BCRB, vise Ă  amĂ©liorer REMD ; elle suppose que les qualitĂ©s de rĂ©ception de lien des cellules adjacentes sont dĂ©pendantes ce qui est, gĂ©nĂ©ralement, plus rĂ©aliste. BCRB utilise les rĂ©seaux BayĂ©siens pour modĂ©liser les dĂ©pendances en vue d’estimer la qualitĂ© du lien de rĂ©ception avec une meilleure prĂ©cision. La troisiĂšme contribution, appelĂ©e RICS, offre un accĂšs fiable Ă  Internet. RICS propose un modĂšle d’optimisation, avec une rĂ©solution exacte optimale Ă  l'aide d’une technique de rĂ©duction de la dimension spatiale, pour le dĂ©ploiement des passerelles. Chaque passerelle utilise BCRB pour Ă©tablir une communication fiable avec les vĂ©hicules.Vehicular networks aim to enable a plethora of safety and infotainment applications. Safety applications aim to preserve people's lives (e.g., by helping in avoiding crashes) while infotainment applications focus on enhancing the passengers’ experience. These applications, especially safety applications, have stringent requirements in terms of reliability and delay; indeed, dissemination of an emergency message (e.g., by a vehicle/sender involved in a crash) should be reliable while satisfying short delay requirements. Note, that multi-hop dissemination is needed to reach all vehicles, in the target area, that may be outside the transmission range of the sender. Several schemes have been proposed to provide reliability and short delay for vehicular applications. However, these schemes have several limitations. Thus, the design of new solutions, to meet the requirement of vehicular applications in terms of reliability while keeping low end-to-end delay, is required. In this thesis, we propose three schemes. The first scheme is a multi-hop reliable emergency message dissemination scheme, called REMD, which guarantees a predefined reliability , using message repetitions/retransmissions, while satisfying short delay requirements. It computes an optimal number of repetitions based on the estimation of link reception quality at different locations (called cells) in the transmission range of the sender; REMD assumes that link reception qualities of adjacent cells are independent. It also adequately selects a number of vehicles, called forwarders, that cooperate in repeating the emergency message with the objective to satisfy multi-hop reliability requirements. The second scheme, called BCRB, overcomes the shortcoming of REMD by assuming that link reception qualities of adjacent cells are dependent which is more realistic in real-life scenarios. BCRB makes use of Bayesian networks to model these dependencies; this allows for more accurate estimation of link reception qualities leading to better performance of BCRB. The third scheme, called RICS, provides internet access to vehicles by establishing multi-hop reliable paths to gateways. In RICS, the gateway placement is modeled as a k-center optimisation problem. A space dimension reduction technique is used to solve the problem in exact time. Each gateway makes use of BCRB to establish reliable communication paths to vehicles

    A PROTOCOL SUITE FOR WIRELESS PERSONAL AREA NETWORKS

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    A Wireless Personal Area Network (WPAN) is an ad hoc network that consists of devices that surround an individual or an object. BluetoothÂź technology is especially suitable for formation of WPANs due to the pervasiveness of devices with BluetoothÂź chipsets, its operation in the unlicensed Industrial, Scientific, Medical (ISM) frequency band, and its interference resilience. BluetoothÂź technology has great potential to become the de facto standard for communication between heterogeneous devices in WPANs. The piconet, which is the basic BluetoothÂź networking unit, utilizes a Master/Slave (MS) configuration that permits only a single master and up to seven active slave devices. This structure limitation prevents BluetoothÂź devices from directly participating in larger Mobile Ad Hoc Networks (MANETs) and Wireless Personal Area Networks (WPANs). In order to build larger BluetoothÂź topologies, called scatternets, individual piconets must be interconnected. Since each piconet has a unique frequency hopping sequence, piconet interconnections are done by allowing some nodes, called bridges, to participate in more than one piconet. These bridge nodes divide their time between piconets by switching between Frequency Hopping (FH) channels and synchronizing to the piconet\u27s master. In this dissertation we address scatternet formation, routing, and security to make BluetoothÂź scatternet communication feasible. We define criteria for efficient scatternet topologies, describe characteristics of different scatternet topology models as well as compare and contrast their properties, classify existing scatternet formation approaches based on the aforementioned models, and propose a distributed scatternet formation algorithm that efficiently forms a scatternet topology and is resilient to node failures. We propose a hybrid routing algorithm, using a bridge link agnostic approach, that provides on-demand discovery of destination devices by their address or by the services that devices provide to their peers, by extending the Service Discovery Protocol (SDP) to scatternets. We also propose a link level security scheme that provides secure communication between adjacent piconet masters, within what we call an Extended Scatternet Neighborhood (ESN)
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