133 research outputs found

    GrLS : group-based location service in mobile ad hoc networks

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    2006-2007 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

    Evaluation of Network Mobility Schemes for Terrestrial and Satellite Networks

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    NEtwork MObility (NEMO) supports the mobility of multiple Internet-connected devices. However, NEMO Basic Support Protocol suffers from unoptimized route leading to large latency in communication and header overhead. To optimize route, a plethora of schemes have been proposed. These schemes differ in terms of several performance parameters, such as signaling, end-to-end delay andhandoff latency. However, no performance or cost evaluation exists in the literature to compare the schemes. In addition, mobility management is required to support the mobility of Internet-connected devices in satellite networks. Existing mobility management solutions for satellite networks are unable toprovide connectivity to the Internet when satellites are not directly connected to the ground.In this dissertation, a comprehensive evaluation of the schemes and a mobility management solution for satellite networks using NEMO are provided. The schemes are classified and compared to choose the optimal class. Using analytical and simulation-based models, the schemes in the chosen class are compared based on the performance parameters. The effect of the parameters on transmission Control Protocol, the dominant transport protocol in the Internet, is also evaluated. A cost evaluation is performed to determine the network resource consumption of the schemes. Finally, an architecture and extensions of the basic protocol are presented to apply NEMO in satellite networks. This dissertation fosters the application of NEMO to terrestrial and satellitenetworks by selecting and extending optimal route optimization schemes, and presenting new architecture and protocol

    Ad Hoc Mobility Notification in Wireless Infrastructure Networks

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    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 likely to be highly mobile. Mobility notification should therefore be optimized in order to limit signaling overhead while keeping a good reactivity against terminals mobility. This article presents and studies by simulation different level optimizations applied to a modified Cellular IP protocol

    GrLS: Group-Based Location Service in Mobile Ad Hoc Networks

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    Remote software upload techniques in future vehicles and their performance analysis

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    Updating software in vehicle Electronic Control Units (ECUs) will become a mandatory requirement for a variety of reasons, for examples, to update/fix functionality of an existing system, add new functionality, remove software bugs and to cope up with ITS infrastructure. Software modules of advanced vehicles can be updated using Remote Software Upload (RSU) technique. The RSU employs infrastructure-based wireless communication technique where the software supplier sends the software to the targeted vehicle via a roadside Base Station (BS). However, security is critically important in RSU to avoid any disasters due to malfunctions of the vehicle or to protect the proprietary algorithms from hackers, competitors or people with malicious intent. In this thesis, a mechanism of secure software upload in advanced vehicles is presented which employs mutual authentication of the software provider and the vehicle using a pre-shared authentication key before sending the software. The software packets are sent encrypted with a secret key along with the Message Digest (MD). In order to increase the security level, it is proposed the vehicle to receive more than one copy of the software along with the MD in each copy. The vehicle will install the new software only when it receives more than one identical copies of the software. In order to validate the proposition, analytical expressions of average number of packet transmissions for successful software update is determined. Different cases are investigated depending on the vehicle\u27s buffer size and verification methods. The analytical and simulation results show that it is sufficient to send two copies of the software to the vehicle to thwart any security attack while uploading the software. The above mentioned unicast method for RSU is suitable when software needs to be uploaded to a single vehicle. Since multicasting is the most efficient method of group communication, updating software in an ECU of a large number of vehicles could benefit from it. However, like the unicast RSU, the security requirements of multicast communication, i.e., authenticity, confidentiality and integrity of the software transmitted and access control of the group members is challenging. In this thesis, an infrastructure-based mobile multicasting for RSU in vehicle ECUs is proposed where an ECU receives the software from a remote software distribution center using the road side BSs as gateways. The Vehicular Software Distribution Network (VSDN) is divided into small regions administered by a Regional Group Manager (RGM). Two multicast Group Key Management (GKM) techniques are proposed based on the degree of trust on the BSs named Fully-trusted (FT) and Semi-trusted (ST) systems. Analytical models are developed to find the multicast session establishment latency and handover latency for these two protocols. The average latency to perform mutual authentication of the software vendor and a vehicle, and to send the multicast session key by the software provider during multicast session initialization, and the handoff latency during multicast session is calculated. Analytical and simulation results show that the link establishment latency per vehicle of our proposed schemes is in the range of few seconds and the ST system requires few ms higher time than the FT system. The handoff latency is also in the range of few seconds and in some cases ST system requires less handoff time than the FT system. Thus, it is possible to build an efficient GKM protocol without putting too much trust on the BSs

    Contributions to Vehicular Communications Systems and Schemes

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    La dernière décennie a marqué une grande hausse des applications véhiculaires comme une nouvelle source de revenus et un facteur de distinction dans l'industrie des véhicules. Ces applications véhiculaires sont classées en deux groupes : les applications de sécurité et les applications d'info divertissement. Le premier groupe inclue le changement intelligent de voie, l'avertissement de dangers de routes et la prévention coopérative de collision qui comprend la vidéo sur demande (VoD), la diffusion en direct, la diffusion de météo et de nouvelles et les jeux interactifs. Cependant, Il est à noter que d'une part, les applications véhiculaires d'info divertissement nécessitent une bande passante élevée et une latence relativement faible ; D'autre part, les applications de sécurité requièrent exigent un délai de bout en bout très bas et un canal de communication fiable pour la livraison des messages d'urgence. Pour satisfaire le besoin en applications efficaces, les fabricants de véhicules ainsi que la communauté académique ont introduit plusieurs applications à l’intérieur de véhicule et entre véhicule et véhicule (V2V). Sauf que, l'infrastructure du réseau sans fil n'a pas été conçue pour gérer les applications de véhicules, en raison de la haute mobilité des véhicules, de l'imprévisibilité du comportement des conducteurs et des modèles de trafic dynamiques. La relève est l'un des principaux défis des réseaux de véhicules, car la haute mobilité exige au réseau sans fil de faire la relève en un très court temps. De plus, l'imprévisibilité du comportement du conducteur cause l'échec des protocoles proactifs traditionnels de relève, car la prédiction du prochain routeur peut changer en fonction de la décision du conducteur. Aussi, le réseau de véhicules peut subir une mauvaise qualité de service dans les régions de relève en raison d'obstacles naturels, de véhicules de grande taille ou de mauvaises conditions météorologiques. Cette thèse se concentre sur la relève dans l'environnement des véhicules et son effet sur les applications véhiculaires. Nous proposons des solutions pratiques pour les réseaux actuellement déployés, principalement les réseaux LTE, l'infrastructure véhicule à véhicule (V2V) ainsi que les outils efficaces d’émulateurs de relèves dans les réseaux véhiculaires.----------ABSTRACT: The last decade marked the rise of vehicular applications as a new source of revenue and a key differentiator in the vehicular industry. Vehicular Applications are classified into safety and infotainment applications. The former include smart lane change, road hazard warning, and cooperative collision avoidance; however, the latter include Video on Demand (VoD), live streaming, weather and news broadcast, and interactive games. On one hand, infotainment vehicular applications require high bandwidth and relatively low latency; on the other hand, safety applications requires a very low end to end delay and a reliable communication channel to deliver emergency messages. To satisfy the thirst for practical applications, vehicle manufacturers along with research institutes introduced several in-vehicle and Vehicle to Vehicle (V2V) applications. However, the wireless network infrastructure was not designed to handle vehicular applications, due to the high mobility of vehicles, unpredictability of drivers’ behavior, and dynamic traffic patterns. Handoff is one of the main challenges of vehicular networks since the high mobility puts pressure on the wireless network to finish the handoff within a short period. Moreover, the unpredictability of driver behavior causes the traditional proactive handoff protocols to fail, since the prediction of the next router may change based on the driver’s decision. Moreover, the vehicular network may suffer from bad Quality of Service (QoS) in the regions of handoff due to natural obstacles, large vehicles, or weather conditions. This thesis focuses on the handoff on the vehicular environment and its effect on the vehicular applications. We consider practical solutions for the currently deployed networks mainly Long Term Evolution (LTE) networks, the Vehicle to Vehicle (V2V) infrastructure, and the tools that can be used effectively to emulate handoff on the vehicular networks

    Encaminhamento baseado no contexto em ICNs móveis

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    Over the last couple of decades, vehicular ad hoc networks (VANETs) have been at the forefront of research, yet still are afflicted by high network fragmentation, due to their continuous node mobility and geographical dispersion. To address these concerns, a new paradigm was proposed - Information-Centric Networks(ICN), whose focus is the delivery of Content based on names, being ideal to attend to high latency environments. However, the main proposed solutions for content delivery in ICNs do not take into account the type of content nor the various available communication interfaces in each point of the network, a factor which can be deciding in mobile networks. The scope of this dissertation lies on the use of ICNs concepts for the delivery of both urgent and non-urgent information in urban mobile environments. In order to do so, a context-based forwarding strategy was proposed, with a very clear goal: to take advantage of both packet names and Data, and node's neighborhood analysis in order to successfully deliver content into the network in the shortest period of time, and without worsening network congestion. The design, implementation and validation of the proposed strategy was performed using the ndnSIM platform simulator along with real mobility traces from communication infrastructure of the Porto city. The results show that the proposed context-based forwarding strategy for mobile ICN presents a clear improvement in performance in terms of delivery, while maintaining network overhead at a constant. Furthermore, by means of better pathing and through cooperation with caching mechanisms, lower transmission delays can be attained.Nas últimas décadas, as redes veiculares ad hoc (VANETs) estiveram na vanguarda da pesquisa, mas continuam a ser afetadas por alta fragmentação na rede, devido à mobilidade contínua dos nós e a sua dispersão geográfica. Para abordar estes problemas, um novo paradigma foi proposto - Redes Centradas na Informação (ICN), cujo foco é a entrega de Conteúdo com base em nomes, sendo ideal para atender ambientes de alta latência. No entanto, as principais soluções propostas para entrega de conteúdo em ICNs não têm em conta o tipo de conteúdo nem as várias interfaces de comunicação disponíveis em cada ponto da rede, fator que pode ser determinante em redes móveis. O objetivo desta dissertação reside no uso dos conceitos de ICNs para a entrega de informações urgentes e não urgentes em ambientes móveis urbanos. Para isso, foi proposta uma estratégia de encaminhamento baseada em contexto, com um objetivo muito claro: tirar proveito do nome e dados dos pacotes, e da análise de vizinhança dos nós, com vista em fornecer com êxito o conteúdo para a rede no menor período de tempo e sem piorar o congestionamento da rede. O desenho, implementação e validação da estratégia proposta foram realizados usando o simulador ndnSIM, juntamente com traces reais de mobilidade da infraestrutura de comunicação da cidade do Porto. Os resultados mostram que a estratégia de encaminhamento baseada em contexto proposta para o ICN móvel apresenta uma clara melhoria no desempenho em termos de entrega, mantendo a carga da rede constante. Além disso, através da escolha de melhores caminhos e através da cooperação com mecanismos de armazenamento em cache, é possível alcançar atrasos de transmissão mais baixos.Mestrado em Engenharia de Computadores e Telemátic

    On-demand security and QoS optimization in mobile ad hoc networks

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    Scope and Method of Study: Security often comes with overhead that will impact link Quality of Service (QoS) performance. In this dissertation, we propose an on-demand security and QoS optimization architecture in mobile ad hoc networks that automatically adapts network security level to changes in network topology, traffic condition, and link QoS requirements, so as to keep the security and QoS at optimum conditions. In order to achieve the overall objective, we introduce three basic frameworks: a policy based plug-in security framework, a multi-layer QoS guided routing algorithm, and a Proportional Integral Derivative (PID) feedback control based security and QoS optimization framework. The research has been evaluated with the network simulator ns-2. Finally, we propose an attack tree and state machine based security evaluation mechanism for ad hoc networks: a new security measurement metric.Findings and Conclusions: Simulations have been done for small and large network sizes, low and high communication ratios, as well as low and high mobility scenarios. The simulations show that the proposed on-demand security and QoS optimization architecture can produce similar performance to non-secure QoS routing protocol under various traffic loads. It provides more secure ad hoc networks without compromising the QoS performance, especially under light and medium traffic conditions

    Effective Mobile Routing Through Dynamic Addressing

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    Military communications has always been an important factor in military victory and will surely play an important part in future combat. In modern warfare, military units are usually deployed without existing network infrastructure. The IP routing protocol, designed for hierarchical networks cannot easily be applied in military networks due to the dynamic topology expected in military environments. Mobile ad-hoc networks (MANETs) represent an appropriate network for small military networks. But, most ad-hoc routing protocols suffer from the problem of scalability for large networks. Hierarchical routing schemes based on the IP address structure are more scalable than ad-hoc routing but are not flexible for a network with very dynamic topology. This research seeks a compromise between the two; a hybrid routing structure which combines mobile ad-hoc network routing with hierarchical network routing using pre-planned knowledge about where the various military units will be located and probable connections available. This research evaluates the performance of the hybrid routing and compares that routing with a flat ad-hoc routing protocol, namely the Ad-hoc On-demand Distance Vector (AODV) routing protocol with respect to goodput ratio, packet end to- end delay, and routing packet overhead. It shows that hybrid routing generates lower routing control overhead, better goodput ratio, and lower end-to-end packet delay than AODV routing protocol in situations where some a-priori knowledge is available
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