Download or read book Routage adaptatif et stabilit dans les r seaux maill s sans fil written by Mustapha Boushaba and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Grâce à leur flexibilité et à leur facilité d'installation, les réseaux maillés sans fil (WMNs) permettent un déploiement d'une infrastructure à faible coût. Ces réseaux étendent la couverture des réseaux filaires permettant, ainsi, une connexion n'importe quand et n'importe où. Toutefois, leur performance est dégradée par les interférences et la congestion. Ces derniers causent des pertes de paquets et une augmentation du délai de transmission d'une façon drastique. Dans cette thèse, nous nous intéressons au routage adaptatif et à la stabilité dans ce type de réseaux. Dans une première partie de la thèse, nous nous intéressons à la conception d'une métrique de routage et à la sélection des passerelles permettant d'améliorer la performance des WMNs. Dans ce contexte nous proposons un protocole de routage à la source basé sur une nouvelle métrique. Cette métrique permet non seulement de capturer certaines caractéristiques des liens tels que les interférences inter-flux et intra-flux, le taux de perte des paquets mais également la surcharge des passerelles. Les résultats numériques montrent que la performance de cette métrique est meilleure que celle des solutions proposées dans la littérature. Dans une deuxième partie de la thèse, nous nous intéressons à certaines zones critiques dans les WMNs. Ces zones se trouvent autour des passerelles qui connaissent une concentration plus élevé du trafic ; elles risquent de provoquer des interférences et des congestions. À cet égard, nous proposons un protocole de routage proactif et adaptatif basé sur l'apprentissage par renforcement et qui pénalise les liens de mauvaise qualité lorsqu'on s'approche des passerelles. Un chemin dont la qualité des liens autour d'une passerelle est meilleure sera plus favorisé que les autres chemins de moindre qualité. Nous utilisons l'algorithme de Q-learning pour mettre à jour dynamiquement les coûts des chemins, sélectionner les prochains nœuds pour faire suivre les paquets vers les passerelles choisies et explorer d'autres nœuds voisins. Les résultats numériques montrent que notre protocole distribué, présente de meilleurs résultats comparativement aux protocoles présentés dans la littérature. Dans une troisième partie de cette thèse, nous nous intéressons aux problèmes d'instabilité des réseaux maillés sans fil. En effet, l'instabilité se produit à cause des changements fréquents des routes qui sont causés par les variations instantanées des qualités des liens dues à la présence des interférences et de la congestion. Ainsi, après une analyse de l'instabilité, nous proposons d'utiliser le nombre de variations des chemins dans une table de routage comme indicateur de perturbation des réseaux et nous utilisons la fonction d'entropie, connue dans les mesures de l'incertitude et du désordre des systèmes, pour sélectionner les routes stables. Les résultats numériques montrent de meilleures performances de notre protocole en comparaison avec d'autres protocoles dans la littérature en termes de débit, délai, taux de perte des paquets et l'indice de Gini.
Download or read book M triques de routage dans les r seaux maill s sans fil written by Yaye Sarr and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Ces dernières années, les technologies sans fil ont connu un essor fulgurant. Elles ont permis la mise en place de réseaux sans fil à hautes performances. Les réseaux maillées sans fil (RMSF) sont une nouvelle génération de réseaux sans fil qui offrent des débits élevés par rapport aux réseaux Wi-Fi (Wireless Fidelity) classiques et aux réseaux ad-hoc. Ils présentent de nombreux avantages telles que leur forte tolérance aux pannes, leur robustesse, leur faible coût etc. Les routeurs des RMSF peuvent disposer de plusieurs interfaces radio et chaque interface peut opérer sur plusieurs canaux distincts, c'est des RMSF multiples-radios, multiples-canaux. Ce type de réseau peut accroître de manière considérable les performances des RMSF. Cependant plusieurs problèmes subsistent et doivent être résolus notamment celui du routage. Le routage dans les RMSF demeure un défi majeur. Le but des protocoles de routage est de trouver les meilleures routes i.e. des routes qui maximisent les débits et minimisent les délais, lors de l'acheminement du trafic. La qualité des routes dans les RMSF peut être fortement affectée par les interférences, les collisions, les congestions etc. Alors les protocoles doivent être en mesure de détecter ces problèmes pour pouvoir en tenir compte lors de la sélection des routes. Plusieurs études ont été dédiées aux métriques et aux protocoles de routage dans les RMSF afin de maximiser les performances de celles ci. Mais la plupart ne prennent pas en considération toutes les contraintes telles que les interférences, le problème des stations cachées etc. Ce mémoire propose une nouvelle métrique de routage pour RMSF. Nous avons mis en place une nouvelle métrique de routage pour RMSF appelée MBP (Metric Based on Probabilities). Cette métrique est destinée aux RMSF mono-radio ou multiples-radios. Elle permet d'éviter les routes à forte ii interférence. Les résultats des simulations ont montré que MBP présente des améliorations par rapport à certaines métriques : ETT, WCETT et iAWARE qui sont connues dans le domaine.
Download or read book Routage et Stabilit dans les R seaux Ad Hoc written by Hanen Idoudi and published by Editions Universitaires Europeennes. This book was released on 2011 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les reseaux ad hoc sont des reseaux sans fils composes de noeuds ayant de faibles ressources en energie et pouvant apparaitre et disparaitre, ainsi que se deplacer aleatoirement. Cet ouvrage est motive par l'etude des performances du routage dans les reseaux mobiles ad hoc et la proposition de nouvelles techniques plus efficaces palliant a l'instabilite que presente la topologie de ces reseaux. Nous avons propose un modele simple pour les reseaux ad hoc, modelisant la connectivite du reseau. Nous l'avons utilise pour mettre en exergue le probleme des incertitudes dans le routage proactif dans les reseaux ad hoc. Puis, nous avons propose un modele probabiliste generique pour la selection de routes stables. Nous avons, par la suite, augmente ce premier modele pour definir un routage plus efficace combinant le critere probabilite d'existence des routes et limitation des longueurs des chemins. Finalement, nous avons propose une technique de routage polymorphe combinant les principes et les avantages de la technique proactive et celle probabiliste. Diverses simulations nous ont permis de prouver l'apport de nos propositions en terme de gain de taux de validite des routes."
Download or read book Qualit de Service Et Routage Dans Les R seaux Maill s Sans Fil written by Usman Ashraf and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents three contributions in the area of routing and Quality of Service for IEEE 802.11-based Wireless Mesh Networks. The first contribution defines a routing metric for the selection of route by taking into consideration the performance of wireless links in terms of physical interference (which causes packet losses), logical interference (which causes delay) and the capacity of the links. The performance evaluation of the proposed metric compared to the popular existing metrics shows an improvement in the performance of the network. The second contribution improves the route maintenance mechanism most often used by reactive routing protocols. The existing mechanism considers a route as broken if any of the links in the route experiences multiple successive transmission failures. Our study shows that the transmission failures are often caused by transient problems on the wireless link (noise, interference etc). We propose a novel mechanism of route maintenance which distinguishes between links with temporary or transient transmission problems compared to those with sustained problems in order to make a coherent decision about link breakage (and consequently route breakage). The performance evaluation shows a substantial improvement in the performance of the network. The final contribution proposes a framework for providing Quality of Service (bandwidth guarantee) in multi-radio multi-channel wireless mesh networks. The framework integrates a reactive routing protocol coupled with an admission control mechanism and load balancing. The framework exploits link diversity between neighboring nodes to improve the flow admission ratio with bandwidth guarantees.
Download or read book Routage et stabilit dans les r seaux ad hoc written by Hanen Idoudi and published by . This book was released on 2008 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les réseaux ad hoc sont des réseaux sans fils composés de noeuds souvent mobiles ayant de faibles ressources en énergie et pouvant apparaître et disparaître, ainsi que se déplacer aléatoirement. Ces caractéristiques contraignent les réseaux ad hoc d'avoir une topologie aléatoire et dynamique. Ceci rend également la tâche de routage particulièrement difficile. Notre thèse est axée et motivée par l'étude des performances du routage dans les réseaux mobiles ad hoc (MANETs) et la proposition de nouvelles techniques plus efficaces palliant à l'instabilité souvent accrue et aléatoire que présente la topologie d'un réseau MANET. Nous avons proposé, en un premier temps, un modèle simple de réseaux ad hoc, que nous avons appelé MarkovNet, qui a l'avantage de modéliser la connectivité du réseau. Nous avons utilisé MarkovNet pour mettre en exergue le problème des incertitudes dans le routage proactif dans les réseaux ad hoc. Dans un second temps, nous avons proposé sur la base de MarkovNet, un modèle probabiliste générique de sélection de routes stables. Nous avons par ailleurs, augmenté ce modèle pour définir un routage proactif plus efficace combinant le critère probabilité d'existence des routes et limitation des longueurs des chemins. Diverses simulations nous ont permis de trouver l'apport de nos propositions en terme de gain de validité, autrement dit en pourcentage de routes existantes calculées. Notre troisième contribution a été finalement la proposition d'une technique de routage polymorphe qui combine l'utilisation de la technique proactive et probabiliste afin de profiter des avantages de chacune.
Download or read book Building Wireless Community Networks written by Rob Flickenger and published by "O'Reilly Media, Inc.". This book was released on 2003 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Building Wireless Community Networks is about getting people online using wireless network technology. The 802.11b standard (also known as WiFi) makes it possible to network towns, schools, neighborhoods, small business, and almost any kind of organization. All that's required is a willingness to cooperate and share resources. The first edition of this book helped thousands of people engage in community networking activities. At the time, it was impossible to predict how quickly and thoroughly WiFi would penetrate the marketplace. Today, with WiFi-enabled computers almost as common as Ethernet, it makes even more sense to take the next step and network your community using nothing but freely available radio spectrum. This book has showed many people how to make their network available, even from the park bench, how to extend high-speed Internet access into the many areas not served by DSL and cable providers, and how to build working communities and a shared though intangible network. All that's required to create an access point for high-speed Internet connection is a gateway or base station. Once that is set up, any computer with a wireless card can log onto the network and share its resources. Rob Flickenger built such a network in northern California, and continues to participate in network-building efforts. His nuts-and-bolts guide covers: Selecting the appropriate equipment Finding antenna sites, and building and installing antennas Protecting your network from inappropriate access New network monitoring tools and techniques (new) Regulations affecting wireless deployment (new) IP network administration, including DNS and IP Tunneling (new) His expertise, as well as his sense of humor and enthusiasm for the topic, makes Building Wireless Community Networks a very useful and readable book for anyone interested in wireless connectivity.
Download or read book Forces of Production written by David Noble and published by Routledge. This book was released on 2017-07-12 with total page 749 pages. Available in PDF, EPUB and Kindle. Book excerpt: Focusing on the design and implementation of computer-based automatic machine tools, David F. Noble challenges the idea that technology has a life of its own. Technology has been both a convenient scapegoat and a universal solution, serving to disarm critics, divert attention, depoliticize debate, and dismiss discussion of the fundamental antagonisms and inequalities that continue to beset America. This provocative study of the postwar automation of the American metal-working industry—the heart of a modern industrial economy—explains how dominant institutions like the great corporations, the universities, and the military, along with the ideology of modern engineering shape, the development of technology. Noble shows how the system of "numerical control," perfected at the Massachusetts Institute of Technology (MIT) and put into general industrial use, was chosen over competing systems for reasons other than the technical and economic superiority typically advanced by its promoters. Numerical control took shape at an MIT laboratory rather than in a manufacturing setting, and a market for the new technology was created, not by cost-minded producers, but instead by the U. S. Air Force. Competing methods, equally promising, were rejected because they left control of production in the hands of skilled workers, rather than in those of management or programmers. Noble demonstrates that engineering design is influenced by political, economic, managerial, and sociological considerations, while the deployment of equipment—illustrated by a detailed case history of a large General Electric plant in Massachusetts—can become entangled with such matters as labor classification, shop organization, managerial responsibility, and patterns of authority. In its examination of technology as a human, social process, Forces of Production is a path-breaking contribution to the understanding of this phenomenon in American society.
Download or read book Wireless Hacks written by Rob Flickenger and published by "O'Reilly Media, Inc.". This book was released on 2003 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: Continuing with the successful Hack Series, this title provides real-world working examples of how to make useful things happen with wireless equipment.
Download or read book Falling Through the Net written by United States. National Telecommunications and Information Administration and published by . This book was released on 1999 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Polar orbiting environmental satellites written by United States. Government Accountability Office and published by . This book was released on 2012 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ultra Wide Band Antennas written by Xavier Begaud and published by John Wiley & Sons. This book was released on 2013-03-04 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultra Wide Band Technology (UWB) has reached a level of maturity that allows us to offer wireless links with either high or low data rates. These wireless links are frequently associated with a location capability for which ultimate accuracy varies with the inverse of the frequency bandwidth. Using time or frequency domain waveforms, they are currently the subject of international standards facilitating their commercial implementation. Drawing up a complete state of the art, Ultra Wide Band Antennas is aimed at students, engineers and researchers and presents a summary of internationally recognized studies.
Download or read book MIMO written by Alain Sibille and published by Academic Press. This book was released on 2010-12-03 with total page 385 pages. Available in PDF, EPUB and Kindle. Book excerpt: Foreword from Arogyaswami Paulraj, Professor (Emeritus), Stanford University (USA) - The first book to show how MIMO principles can be implemented in today's mobile broadband networks and components - Explains and solves some of the practical difficulties that arise in designing and implementing MIMO systems - Both theory and implementation sections are written in the context of the most recent standards: IEEE 802.11n (WiFi); IEEE 802.16 (WIMAX); 4G networks (3GPP/3GPP2, LTE)
Download or read book Pervasive Mobile and Ambient Wireless Communications written by Roberto Verdone and published by Springer Science & Business Media. This book was released on 2012-01-02 with total page 696 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reporting the findings of COST 2100, a major European intergovernmental project, this volume offers system designers a good source of guidelines based on channel characterization and measurement-based modeling, as well as worthwhile ideas for future research.
Download or read book Proof Theory and Automated Deduction written by Jean Goubault-Larrecq and published by Springer Science & Business Media. This book was released on 2001-11-30 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: Interest in computer applications has led to a new attitude to applied logic in which researchers tailor a logic in the same way they define a computer language. In response to this attitude, this text for undergraduate and graduate students discusses major algorithmic methodologies, and tableaux and resolution methods. The authors focus on first-order logic, the use of proof theory, and the computer application of automated searches for proofs of mathematical propositions. Annotation copyrighted by Book News, Inc., Portland, OR
Download or read book Digital Transformation in Financial Services written by Claudio Scardovi and published by Springer. This book was released on 2017-09-04 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book analyzes the set of forces driving the global financial system toward a period of radical transformation and explores the transformational challenges that lie ahead for global and regional or local banks and other financial intermediaries. It is explained how these challenges derive from the newly emerging post-crisis structure of the market and from shadow and digital players across all banking operations. Detailed attention is focused on the impacts of digitalization on the main functions of the financial system, and particularly the banking sector. The author elaborates how an alternative model of banking will enable banks to predict, understand, navigate, and change the external ecosystem in which they compete. The five critical components of this model are data and information mastering; effective use of applied analytics; interconnectivity and “junction playing”; development of new business solutions; and trust and credibility assurance. The analysis is supported by a number of informative case studies. The book will be of interest especially to top and middle managers and employees of banks and financial institutions but also to FinTech players and their advisers and others.
Download or read book Internet Dreams written by Mark Stefik and published by MIT Press. This book was released on 1997 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt: Internet Dreams illuminates not only how "the Net" is being created, but also stories about ourselves as our lives become electronically interconnected. Stefik explores some of the most provocative writings about the Internet to tease out the deeper metaphors and myths. 24 illustrations.
Download or read book Simply This Amen written by Donna McLin and published by . This book was released on 2019-12 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: This prayer book was written over a two-year span. The prayers started one night when my daughter and I could not sync our time to pray together on one particular night in March 2017. While preparing for bed, the Lord said to me, "Just write a prayer and put it on Facebook". I did and the rest is history. You are now holding what it is that the Lord has done with these prayers. Each night with the exception of being away from home with no phone service, or during times of fasting, I wrote a prayer each night and posted them on Facebook. I have been told by many people along the way that they do not know how to pray. It is my prayer that this book will be a foundation for those who feel that they do not know how to pray or who simply need a prayer devotional.
