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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
491

An Energy-aware multipath routing extension for heterogeneous Ad hoc networks

Lima Junior, Josias Barbosa de 05 1900 (has links)
Submitted by João Arthur Martins (joao.arthur@ufpe.br) on 2015-03-11T18:10:20Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertaçao JOSIAS de LIMA JUNIOR.pdf: 4252506 bytes, checksum: 714cb7aa7e2dc62943c697bd35a222ed (MD5) / Approved for entry into archive by Daniella Sodre (daniella.sodre@ufpe.br) on 2015-03-13T13:00:53Z (GMT) No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertaçao JOSIAS de LIMA JUNIOR.pdf: 4252506 bytes, checksum: 714cb7aa7e2dc62943c697bd35a222ed (MD5) / Made available in DSpace on 2015-03-13T13:00:53Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertaçao JOSIAS de LIMA JUNIOR.pdf: 4252506 bytes, checksum: 714cb7aa7e2dc62943c697bd35a222ed (MD5) Previous issue date: 2013-05 / Recent years have witnessed the emergence of new communication techniques in Computer Science that use both wireless technologies and self-organizing features. Their combination eliminates the need for using pre-defined wired structures and prior configurations. In this work, we develop a simulated version, using the network simulator 3 (ns-3), of the Heterogeneous Technologies Routing (HTR) framework that is suitable for interconnecting devices in a heterogeneous ad hoc network, extending its supported heterogeneous technologies with the addition of WiMAX and LTE devices, proposes an extension to enable multipath routing over this framework and investigates the impact of tuning routing parameters on convergence interval and energy consumption. Although a large number of works exist that investigate the tuning of routing parameter settings, to the best of our knowledge, none of them investigate the impact of these on protocol convergence and energy consumption. Multipath HTR routing, the extension we propose, offers several benefits such as load balancing, fault tolerance, routing loop prevention, energy-conservation, low end-to-end delay, and congestion avoidance, among others. This work performs a comparative analysis of the proposed HTR extension, with the baseline HTR, and the widely used Optimized Link State Routing (OLSR) protocol. Moreover, we investigate the impacts of tuning the HELLO refresh interval and perform a comparative analysis of the tuned HTR with the OLSR protocol. Both evaluations are validated through the simulation of heterogeneous technologies such as WiMAX, 3GPP LTE and Wi-Fi. Results show that the multipath extension effectively improves the data delivery ratio, and reduces the end-to-end delay without major impact on network energy consumption. For the tuned HTR, results show that varying the HELLO refresh interval can improve the convergence of the protocol and reduce the energy consumption. / Recentemente, novas técnicas de comunicação surgiram que usam tecnologia sem fio e são capazes de se autoconfigurar. A combinação desses fatores elimina a necessidade de utilizar estruturas cabeadas e configurações pré-definidas. Neste trabalho, o autor desenvolve uma versão simulada, através do simulador de rede “network Simulator 3” (ns-3), do arcabouço “Heterogeneous Technologies Routing” (HTR), que se propõe à interconectar dispositivos em redes heterogêneas ad hoc, estendendo o seu suporte às tecnologias heterogêneas com a adição de dispositivos WiMAX e LTE, propõe uma extensão para fornecer um roteamento baseado em múltiplos caminhos (“Multipath”) e investiga o impacto de modificar os parâmetros de configuração do roteamento no tempo de convergência da rede e consumo de energia. Apesar de um grande número de obras existentes que investigam o impacto da mudança de parâmetros de configuração do roteamento, no meu conhecimento, nenhum deles investiga o impacto destes no tempo de convergência do protocolo e consumo de energia. O “Multipath HTR”, a extensão proposta, oferece vários benefícios como balanceamento de carga, tolerância a falhas, prevenção de “loops” de roteamento, conservação de energia, baixo atraso fim-a-fim, e evita o congestionamento, entre outros. Este trabalho faz uma análise comparativa da extensão ao HTR proposta, com a base do HTR, e o protocolo amplamente utilizado “Optimized Link State Routing” (OLSR). Além disso, o esse trabalho investiga o impacto de variar o intervalo de envio de mensagens de HELLO e realiza uma análise comparativa do HTR modificado (“Tuned HTR”) com o protocolo OLSR. As duas avaliações são realizadas através de simulação usando tecnologias heterogêneas como WiMAX, 3GPP LTE e Wi-Fi. Resultados mostram que a extensão de múltiplos caminhos proposta melhora a taxa de transmissão de dados, e reduz o atraso fim-a-fim sem maiores impactos no consumo de energia da rede. Para o “Tuned HTR”, resultados mostram que a variação do intervalo de envio de mensagens de HELLO pode melhorar a convergência do protocolo e reduz o consumo de energia.
492

Misbehaviors detection schemes in mobile ad hoc networks / Une approche décentralisée pour la détection de comportements malveillants dans les réseaux MANETs

Rmayti, Mohammad 30 September 2016 (has links)
Avec l’évolution des besoins d’utilisateurs, plusieurs technologies de réseaux sans fil ont été développées. Parmi ces technologies, nous trouvons les réseaux mobiles ad hoc (MANETs) qui ont été conçus pour assurer la communication dans le cas où le déploiement d’une infrastructure réseaux est coûteux ou inapproprié. Dans ces réseaux, le routage est une fonction primordiale où chaque entité mobile joue le rôle d’un routeur et participe activement dans le routage. Cependant, les protocoles de routage ad hoc tel qu’ils sont conçus manquent de contrôle de sécurité. Sur un chemin emprunté, un nœud malveillant peut violemment perturber le routage en bloquant le trafic. Dans cette thèse, nous proposons une solution de détection des nœuds malveillants dans un réseau MANET basée sur l’analyse comportementale à travers les filtres bayésiens et les chaînes de Markov. L’idée de notre solution est d’évaluer le comportement d’un nœud en fonction de ses échanges avec ses voisins d’une manière complètement décentralisée. Par ailleurs, un modèle stochastique est utilisé afin de prédire la nature de comportement d’un nœud et vérifier sa fiabilité avant d’emprunter un chemin. Notre solution a été validée via de nombreuses simulations sur le simulateur NS-2. Les résultats montrent que la solution proposée permet de détecter avec précision les nœuds malveillants et d’améliorer la qualité de services de réseaux MANETs / With the evolution of user requirements, many network technologies have been developed. Among these technologies, we find mobile ad hoc networks (MANETs) that were designed to ensure communication in situations where the deployment of a network infrastructure is expensive or inappropriate. In this type of networks, routing is an important function where each mobile entity acts as a router and actively participates in routing services. However, routing protocols are not designed with security in mind and often are very vulnerable to node misbehavior. A malicious node included in a route between communicating nodes may severely disrupt the routing services and block the network traffic. In this thesis, we propose a solution for detecting malicious nodes in MANETs through a behavior-based analysis and using Bayesian filters and Markov chains. The core idea of our solution is to evaluate the behavior of a node based on its interaction with its neighbors using a completely decentralized scheme. Moreover, a stochastic model is used to predict the nature of behavior of a node and verify its reliability prior to selecting a path. Our solution has been validated through extensive simulations using the NS-2 simulator. The results show that the proposed solution ensures an accurate detection of malicious nodes and improve the quality of routing services in MANETs
493

Méthodes utilisant des fonctions de croyance pour la gestion des informations imparfaites dans les réseaux de véhicules / Methods using belief functions to manage imperfect information in vehicular networks

Bou Farah, Mira 02 December 2014 (has links)
La popularisation des véhicules a engendré des problèmes de sécurité et d’environnement. Desprojets ont été lancés à travers le monde pour améliorer la sécurité sur la route, réduire l’encombrementdu trafic et apporter plus de confort aux conducteurs. L’environnement des réseaux devéhicules est complexe et dynamique, les sources sont souvent hétérogènes, de ce fait les informationséchangées peuvent souvent être imparfaites. La théorie des fonctions de croyance modélisesouplement les connaissances et fournit des outils riches pour gérer les différents types d’imperfection.Elle est utilisée pour représenter l’incertitude, gérer les différentes informations acquises etles fusionner. Nous nous intéressons à la gestion des informations imparfaites échangées entre lesvéhicules concernant les événements sur la route. Les événements locaux et les événements étendusn’ayant pas les mêmes caractéristiques, les travaux réalisés les distinguent. Dans un environnementsans infrastructure où chaque véhicule a son propre module de fusion, l’objectif est de fournir auxconducteurs la synthèse la plus proche possible de la réalité. Différents modèles fondés sur desfonctions de croyance sont proposés et différentes stratégies sont étudiées : affaiblir ou renforcervers l’absence de l’événement pour prendre en compte le vieillissement des messages, garder lesmessages initiaux ou seulement le résultat de la fusion dans la base des véhicules, considérer la miseà jour du monde, prendre en compte l’influence du voisinage pour gérer la spatialité des embouteillages.Les perspectives restent nombreuses, certaines sont développées dans ce manuscrit commela généralisation des méthodes proposées à tous les événements étendus tels que les brouillards. / The popularization of vehicles has created safety and environmental problems. Projects havebeen launched worldwide to improve road safety, reduce traffic congestion and bring more comfortto drivers. The vehicle network environment is dynamic and complex, sources are often heterogeneous,and therefore the exchanged information may be imperfect. The theory of belief functionsoffers flexibility in uncertainty modeling and provides rich tools for managing different types of imperfection.It is used to represent uncertainty, manage and fuse the various acquired information.We focus on the management of imperfect information exchanged between vehicles concerningevents on the road. The carried work distinguishes local events and spatial events, which do nothave the same characteristics. In an environment without infrastructure where each vehicle is afusion center and creates its own vision, the goal is to provide to each driver the synthesis of thesituation on the road as close as possible to the reality. Different models using belief functionsare proposed. Different strategies are considered: discount or reinforce towards the absence of theevent to take into account messages ageing, keep the original messages or just the fusion result invehicle database, consider the world update, manage the spatiality of traffic jam events by takinginto account neighborhood. Perspectives remain numerous; some are developed in the manuscriptas the generalization of proposed methods to all spatial events such as fog blankets.
494

Routing protocols for indoor wireless ad-hoc networks: a cross-layer perspective

Dricot, Jean-Michel 01 June 2007 (has links)
The all-over trend for an universal access and ubiquitous access to the Internet is driving a revolution in our societies. In order to support this era of nomadic applications, new flexible network architectures have emerged. They are referred to as “wireless ad-hoc networks.” <p><p>Since human-operated devices will more likely be used indoor, it leads to many issues related to the strength of the fading in this environment. Recently, it has been suggested that a possible interaction might exist between various parameters of the ad-hoc networks and, more precisely, between the propagation model and the routing protocol. <p><p>To address this question, we present in this dissertation a cross-layer perspective of the analysis of these indoor ad-hoc networks. Our reasoning is made of four stages. First, the cross-layer interactions are analyzed by the means of multivariate statistical techniques. Since a cross-layering between the physical layer and the routing protocol has been proven to be significant, we further investigate the possible development a physical layer-constrained routing algorithm. <p><p>Second, fundamental equations governing the wireless telecommunications systems are developed in order to provide insightful informations on how a reliable routing strategy should be implemented in a strongly-faded environment. After that, and in order to allow a better spatial reuse, the routing protocol we propose is further enhanced by the adjonction of a power control algorithm. This last feature is extensively analyzed and a closed-form expression of the link probability of outage in presence of non-homogeneous transmission powers is given. Numerous simulations corroborate the applicability and the performance of the derived protocol. Also, we evaluate the gain, in terms of radio channel ressources, that has been achieved by the means of the power control algorithm. <p><p>Third, an architecture for the interconnection with a cellular network is investigated. A closed-form expression of the relaying stability of a node is given. This equation expresses the minimal requirement that a relaying node from the ad-hoc network must fullfil in order to bridge properly the connections to the base-station. <p><p>Finally, a real-life implementation is provided as a validation of the applicability of this novel ad-hoc routing protocol. It is concluded that, both from the performance and the spatial re-use point-of-views, it can be taken advantage from the cross-layering between the physical and the routing layers to positively enhance the networking architectures deployed in an indoor environment. / Doctorat en sciences appliquées / info:eu-repo/semantics/nonPublished
495

Réseaux ad hoc véhiculaires : vers une dissémination de données efficace, coopérative et fiable / Vehicular ad hoc networks : towards efficient, collaborativeand reliable data dissemination

Haddadou, Nadia 16 June 2014 (has links)
Les réseaux ad hoc véhiculaires (VANETs) permettent le partage de différents types de données entre les véhicules, de manière collaborative. Dans cette thèse, nous nous sommes tout particulièrement intéressés aux applications de sûreté et de sécurité routière, dédiées à l'échange des informations sur l'état de l'environnement routier. Les contraintes de ces applications en termes de qualité de services sont des plus rigoureuses, car l'acheminent de leurs données doit être exhaustif et ne souffrir d'aucun retard pour assurer une information utile et en temps opportun au profit de tous les usagers concernés. Cet acheminement doit faire face aux difficultés induites par la dispersion et la forte mobilité des véhicules, l'absence ou l'insuffisance d'infrastructure, la densité variable du réseau, la surcharge en informations à envoyer et l'étendue des zones géographiques à couvrir. En effet, la problématique de diffusion des données dans les VANETs s'avère non-triviale et de nombreux verrous scientifiques doivent être levés pour permettre un support efficace, collaboratif et fiable pour les applications de sûreté et de sécurité routière.Plus précisément, nous aborderons la problématique de la dissémination collaborative en se posant trois questions : “comment disséminer les données ? À quel moment le faire ? Mais aussi quoi disséminer et comment inciter à le faire ? ” Nous avons apporté des réponses à travers les trois contributions de cette thèse. La première consiste à proposer une stratégie de dissémination efficace, qui soit adaptée à l'importance de l'information échangée et à sa durée de vie, permettant ainsi d'éviter un processus de diffusion intensif. Celui-ci est inapproprié dans ce cas de figure, car il génère de la congestion et beaucoup de redondance. Une étude de performances par simulation est réalisée, laquelle montre une diminution de 90% du taux de messages redondants par rapport au cas de la diffusion par inondation. Afin d'améliorer plus encore les performances du processus de diffusion des messages de sûreté, nous proposons, dans un second temps, un ordonnanceur pour l'accès au canal de communication qui a pour objectif de réduire le nombre de collisions dues aux synchronisations afférentes à l'utilisation du multi-canal dans le standard IEEE 802.11p/1609.4 et donc élever le taux de réception des données. Nous basons notre proposition sur la théorie de l'arrêt optimal, qui décide du moment opportun pour l'envoi d'une information en conciliant occupation du canal, efficacité de l'envoi et délai d'ajournement toléré par une information. Dans notre cas, la théorie de l'arrêt optimal est formulée par un processus de décision Markovien (MDP). Nous montrons ainsi par simulation une amélioration substantielle du taux de réception (de 25%) et une diminution importante des pertes (de 47%).Après s'être intéressé à l'aspect quantitatif des performances du réseau, nous nous intéresserons ensuite à l'amélioration de la fiabilité du processus de diffusion. Cette fiabilité est obtenue grâce à l'incitation des véhicules à la coopération et à l'exclusion des véhicules malicieux de celui-ci. Ceci est réalisé au travers de la proposition d'un modèle de confiance, inspiré des jeux de signaux. Le modèle crée une situation d'équilibre, tel que les différentes parties le composant ne soient pas tentées de le contourner, ainsi découle une auto-sélection des véhicules, laquelle est rapide et peu coûteuse. À notre connaissance, notre modèle est le seul à s'attaquer aux effets néfastes des deux types de véhicules, malicieux et égoïstes, en même temps. Comme précédemment, nous évaluons les performances de notre solution au travers d'une modélisation par une chaîne de Markov et divers jeux de simulation. Ceci a permis de montrer que 100% des véhicules malicieux sont exclus, avec le maintien d'un taux de coopération élevé dans le réseau, soit une amélioration de 42% / Vehicular Ad Hoc Networks (VANETs) allow sharing different kinds of data between vehicles in a collaborative way. In this thesis, we are particularly interested in road safety applications, designed for the exchange of information on road traffic and conditions. This kind of applications have strict Quality of Service (QoS) requirements, as data must be routed thoroughly and without any delays so for assuring the timely delivery of useful information to the drivers. In this context, data routing must face several issues raised by the high mobility and dispersion of vehicles, inadequate or completely lacking infrastructure, a variable network density, network saturation due to the large of information to deliver, and the size of the geographical areas to cover. Indeed, the problem of data dissemination in VANETs is non-trivial, and several research challenges must be solved in order to provide an efficient, collaborative, and reliable support for road safety applications. Specifically, we will address the problem of collaborative data dissemination through the following three questions: “How to perform data dissemination?”, “When should we do it?”, and “What must be disseminated?” We have provided answers to these questions through the three contributions of this thesis. Our first contribution is an efficient dissemination strategy, specifically tailored to the importance of the exchanged information as well as its lifespan, which is able to avoid the intensive dissemination process that generates network congestion and data redundancy. We confirm our statements and validate the performance of our solution by modeling it using a discrete-time Markov chain, which demonstrates the number of necessary retransmissions for all concerned vehicles to receive information. Moreover, we performed extensive simulations that show a reduction of up to 90% of redundant messages with respect to message flooding dissemination strategies. Next, in order to further improve the road safety message dissemination process, we propose a communications channel access scheduler, which aims at reducing the number of collisions caused by IEEE 802.11p/1609.4 multi-channel synchronizations, and thus improving the data reception rate. We base our solution on the optimal stopping theory, which chooses the right moment to send information by balancing the channel occupancy rate, the data delivery efficiency, and the maximum deferment delay tolerated by the information. To this end, we formulate the optimal stopping theory through a Markov decision process (MDP). We show through simulation-based evaluations an improvement of the reception rate of up to 25% and a reduction of up to 47% of message losses. Finally, after being interested in the quantitative aspect of network performance, we centered our efforts on improving the reliability of the dissemination process, which is obtained by motivating vehicles to cooperate and evicting malicious vehicles from the process. To this end, we propose a trust model inspired on signaling games, which are a type of dynamic Bayesian games. Through the use of our model, equilibrium is achieved, thus resulting in a fast and low-cost vehicle self-selection process. We define the parameters of our trust model through a discrete-time Markov chain model. To the best of our knowledge, our solution is the only existing solution that tackles the negative effects introduced by the presence of both malicious and selfish vehicles in a VANET. We evaluated the performance of our solution by modeling it using a Markov chain, and a set of simulations. Our results show that up to 100% of malicious vehicles are evicted while keeping a high cooperation rate, thus achieving an improvement of 42% when compared to other similar solutions
496

Security issues in Address Autoconfiguration Protocols

Langer, André, Kühnert, Tom 20 April 2007 (has links)
Dynamic address assignment is one of the most important features in wireless ad hoc networks if nodes should be enabled to join and to work in the network by automatically configuring all necessary settings. Different approaches have been developed throughout the last years to achieve this objective of Dynamic Address Autoconfiguration but research primarily focused on efficiency and correctness, less on security issues. Whereas Duplicate Address Detection has become reliable in commonplace scenarios, it is still relatively easy to suspend the whole network functionality in extraordinary situations within the boundaries of a Dynamic Address Configuration Protocol. In this paper, we therefore want to point out shortcomings and weaknesses in existing protocol solutions which address dynamic IP address assignment. We concentrate on a leader-based approach called ODACP and want to propose several solutions which improve the original protocol in such a way that it is safer against malicious host activities. Finally, we will demonstrate the improvements of our solution in a separate test scenario.
497

Betrachtungen zur Energieeffizienz in Funknetzwerken mit geringer Datenrate

Schwieger, Katja 28 February 2006 (has links)
The work in hand considers energy efficiency of data transmission in wireless networks with low data rate (=sensor networks). Often the network nodes are battery operated thus calling for node lifetimes of months or even years. Thus, energy efficiency becomes an important optimisation criteria when designing hardware as well as for the physical transmission, protocol design etc. In order to meet the tight energy constraints, it is necessary to optimise the system as a whole, not just single parameters. This work first shows a derived analysis model for calculating the energy consumption during data transmission. This model is based on a complex state diagram which is evaluated using Mason rules. Using this model the impact of individual parameters on the energy consumption can be computed. Herein the interference of other nodes is included as well. The individual parameters investigated include detection method, modulation scheme, error correction and channel access. The main conclusion is, that higher transmit power can yield decreased energy consumption if the time, which nodes spend in the energy intense active mode, is reduced. Ultra-Wideband-transmission (UWB) using short pulses (Impulse Radio-IR) is currently developing. The potential of this technology is a very simple power-efficient transmitter. Moreover, due to the short pulses, transmission time is short. These two facts promise an energy efficient operation in transmit mode. Nevertheless, performance of simple receivers is still quite low, especially in multi-path environments. Moreover there is the need of powerful synchronisation algorithms. Sensor networks usually possess multi-hop functionality. However, only in severe (block) fading channels multi-hop is more energy efficient than direct transmission. Supposed the transmit power is the same for all nodes, then the transmit power has to be dimensioned for the weakest link. Then, under certain conditions, cooperative relaying schemes can not capitalize the spatial diversity gain. - (This manuscript is also available - in the form of a book - from Dresden: Vogt (Verlag), ISBN:3-938860-02-2) / Die vorliegende Arbeit beschäftigt sich mit der Energieeffizienz der Datenübertragung in Funknetzwerken mit geringer Datenrate (=Sensornetzwerke). Die Netzknoten solcher Netzwerke sind zumeist batteriebetrieben und sollen Betriebsdauern von Monaten bis Jahren erreichen. Daher ist Energieeffizienz ein wichtiges Designmerkmal sowohl beim Hardwareentwurf als auch bei der physikalischen Übertragung, im Protokolldesign usw. Um den energetischen Beschränkungen gerecht zu werden, sollen nicht Einzelparameter optimiert werden, sondern das System insgesamt. In dieser Arbeit wird zunächst ein Analysemodell zur Berechnung des Energieverbrauchs bei der Datenübertragung entwickelt, welches diesen Forderungen gerecht wird. Dieses basiert auf einem komplexen Zustandsdiagramm, welches mit der Mason'schen Regel ausgewertet wird. Dieses Modell nutzend, kann der Einfluss von Einzelparametern auf den Energieverbrauch unter Berücksichtigung der Interferenzen anderer Netzknoten berechnet werden. Als Einzelparameter werden exemplarisch Detektionsverfahren, Modulation, Fehlerschutzkodierung und Kanalzugriff untersucht. Die Grunderkenntnis dieser Betrachtungenen ist, dass höhere Sendeleistungen zu geringerem Energieverbrauch führen, wenn dadurch die Zeit des Netzknotens im energieintensiven Aktiv-Mode verkürzt wird. Ultra-Wideband-Verfahren (UWB) mittels kurzen Pulsen (IR-UWB) befinden sich noch in einer frühen Entwickungsstufe. Das Potential liegt in einem sehr einfachen Senderaufbau, der sehr leistungseffiziente Sender ermöglicht. Aufgrund der kurzen Pulse ist zudem die Übertragungszeit sehr gering. Diese beiden Gegebenheiten lassen auf einen geringen Energieverbrauch hoffen. Allerdings ist die Leistungsfähigkeit von einfachen Empfängern insbesondere in Mehrwegekanälen sehr gering. Desweiteren gibt es noch intensiven Forschungsbedarf für leistungsfähige Synchronisationsalgorithmen. Sensornetzwerke verfügen im Allgemeinen über Multi-Hop-Funktionalität. Energetisch betrachtet, ist deren Einsatz aber nur in starken Blockschwundkanälen sinnvoll. Wird die Sendeleistung aller Netzknoten als konstant angenommen, muss die Sendeleistung auf die schwächste Verbindung dimensioniert werden. Bei kooperativen Vermittlungsverfahren kann dadurch unter bestimmten Bedingungen der räumliche Diversitätsgewinn nicht genutzt werden. - (Die Dissertation ist veröffentlicht im Verlag Vogt, Dresden, ISBN:3-938860-02-2)
498

Městská rozhraní a jejich rozšíření: sensory, čipy a ad-hoc sítě jako nástroje urbánní kultury / Urban interfaces & extensions: sensors, chips, and ad-hoc networks as tools for urban culture

Peterová, Radka January 2011 (has links)
This thesis proposes a DIY environmental sensing approach that empowers citizens to reinvigorate people's awareness of, and concern for, pollution. Current air pollution measuring techniques are described, and a new concept of participatory sensing is presented. I argue that technological advances in sensing, computation, storage, and communication now have the power to turn the near-ubiquitous mobile phone into a global mobile sensing device, and commence the participatory paradigm employing amateurs in environmental data collection. To test the thesis, PAIR, a prototype with interchangeable sensor, was developed. It aims to enable people to sense environment on-the-go and provide users with immediate feedback. Such data can make people learn about their environment, make them aware of air pollution causes, and eventually even bring behavioral changes. Consequently, a user survey and interviews identify strengths and weaknesses of the mobile sensing device, and based on the usability requirements, we conclude design recommendations for further development. Finally, we identify the main benefits amateur data collection and participatory sensing represent for urban dwellers, and we evaluate issues and challenges they have yet to overcome.
499

Performance evaluation of routing protocols using NS-2 and realistic traces on driving simulator

Chen, Mingye 21 May 2014 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / With the rapid growth in wireless mobile communication technology, Vehicular Ad-hoc Network (VANET) has emerged as a promising method to effectively solve transportation-related issues. So far, most of researches on VANETs have been conducted with simulations as the real-world experiment is expensive. A core problem affecting the fidelity of simulation is the mobility model employed. In this thesis, a sophisticated traffic simulator capable of generating realistic vehicle traces is introduced. Combined with network simulator NS-2, we used this tool to evaluate the general performance of several routing protocols and studied the impact of intersections on simulation results. We show that static nodes near the intersection tend to become more active in packet delivery with higher transferred throughput.
500

Implicit Message Integrity Provision : In Heterogeneous Vehicular Systems / Implicit Integritet i Heterogena Fordonsmiljöer Systems

Molloy, Paul January 2023 (has links)
Vehicles on the road today are complex multi-node computer networks. Security has always been a critical issue in the automotive computing industry. It is becoming even more crucial with the advent of autonomous vehicles and driver assistant technology. There is potential for attackers to control vehicles maliciously. Traditionally Original Equipment Manufacturers have relied on physical security and a firewall to secure vehicles but with network connected and autonomous capable vehicles this is not enough. The concept of defence in depth is required. This means not trusting that internal traffic inside the firewall is benign. Each node in the vehicles network should be able to verify the authenticity and validity of communications it receives from other nodes. Implementation of the crypto-graphic systems for doing this is error prone. Therefore a key issue in the thesis is reducing the attack surface by developing these checks in the autonomous vehicle stack in a scalable way so the programmer does not have to be aware of this security layer on a day-to-day basis nor re-implement it for each node in these heterogeneous systems. Although message integrity and authenticity verification have been studied and implemented in many fields, the area of heterogeneous autonomous systems present unique research challenges. There are tight performance constraints due to the real time requirements for vehicle control systems and data publishing rates. It is an open question if this approach can achieve performance within the bounds required for a reliable autonomous vehicle. Additionally the security benefit of scalably automatically generating the message integrity verification code across all of the nodes in a heterogeneous system would help the field quantify the defect reduction and security benefit of this kind of code generation on complex software systems. / Dagens fordon på vägarna är komplexa datanät med flera noder. Säkerheten har alltid varit en viktig fråga inom bilindustrin. Det blir ännu viktigare i och med tillkomsten av autonoma fordon och förarassistentteknik. Det finns en potential för angripare att styra fordon på ett illvilligt sätt. Traditionellt har tillverkare av originalutrustning förlitat sig på fysisk säkerhet och en brandvägg för att säkra fordonen, men med nätverksanslutna och autonoma fordon räcker detta inte längre. Begreppet försvar på djupet är nödvändigt. Detta innebär att man inte kan lita på att den interna trafiken innanför brandväggen är godartad. Varje nod i fordonets nätverk bör kunna kontrollera äktheten och giltigheten hos den kommunikation som den tar emot från andra noder. Genomförandet av kryptografiska system för att göra detta är felkänsligt. En viktig fråga i avhandlingen är därför att minska angreppsytan genom att utveckla dessa kontroller i det autonoma fordonet på ett skalbart sätt så att programmeraren inte behöver vara medveten om detta säkerhetslager dagligen eller implementera det på nytt för varje nod i dessa heterogena system. Även om meddelandeintegritet och äkthetskontroll har studerats och genomförts inom många områden, innebär området heterogena autonoma system unika forskningsutmaningar. Det finns snäva prestandabegränsningar på grund av realtidskraven för fordonskontrollsystem och datapubliceringshastigheter. Det är en öppen fråga om detta tillvägagångssätt kan uppnå prestanda inom de gränser som krävs för ett tillförlitligt autonomt fordon. Dessutom skulle säkerhetsfördelarna med en skalbar automatisk generering av koden för verifiering av meddelandets integritet över alla noder i ett heterogent system hjälpa fältet att kvantifiera felminskningen och säkerhetsfördelarna med denna typ av kodgenerering i komplexa programvarusystem.

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