Les réseaux ad hoc mobiles sont des réseaux qui se forment spontanément grâce à la présence de terminaux mobiles. Ces réseaux sans fil sont de faible capacité. Les nœuds se déplacent librement et de manière imprévisible et ils se déchargent très rapidement. En conséquence, un réseau MANET est très enclin à subir des partitionnements fréquents. Les applications déployées sur de tels réseaux, souffrent de problèmes de disponibilité des données induits par ces partitionnements. La réplication des données constitue un mécanisme prometteur pour pallier ce problème. Cependant, la mise en œuvre d'un tel mécanisme dans un environnement aussi contraint en ressources constitue un réel défi. L'objectif principal est donc de réaliser un mécanisme peu consommateur en ressources. Le second objectif de la réplication est de permettre le rééquilibrage de la charge induite par les requêtes de données. Le choix des données à répliquer ainsi que celui des nœuds optimaux pour le placement des futurs réplicas est donc crucial, spécialement dans le contexte du MANET. Dans cette thèse, nous proposons CReaM (Community-Centric and Resource-Aware Replication Model") un modèle de réplication adapté à un réseau MANET. CReaM fonctionne en mode autonomique : les prises de décisions se basent sur des informations collectées dans le voisinage du nœud plutôt que sur des données globalement impliquant tous les nœuds, ce qui permet de réduire le trafic réseau lié à la réplication. Pour réduire l'usage des ressources induit par la réplication sur un nœud, les niveaux de consommation des ressources sont contrôlés par un moniteur. Toute consommation excédant un seuil prédéfini lié à cette ressource déclenche le processus de réplication. Pour permettre le choix de la donnée à répliquer, une classification multi critères a été proposée (rareté de la donnée, sémantique, niveau de demande); et un moteur d'inférence qui prend en compte l'état de consommation des ressources du nœud pour désigner la catégorie la plus adaptée pour choisir la donnée à répliquer. Pour permettre de placer les réplicas au plus près des nœuds intéressés, CReaM propose un mécanisme pour l'identification et le maintien à jour des centres d'intérêt des nœuds. Les utilisateurs intéressés par un même sujet constituent une communauté. Par ailleurs, chaque donnée à répliquer est estampillée par le ou les sujets au(x)quel(s) elle s'apparente. Un nœud désirant placer un réplica apparenté à un sujet choisira le nœud ayant la plus grande communauté sur ce sujet. Les résultats d'expérimentations confirment la capacité de CReaM à améliorer la disponibilité des données au même niveau que les solutions concurrentes, tout en réduisant la charge liée à la réplication. D'autre part, CReaM permet de respecter l'état de consommation des ressources sur les nœuds.

Currently there is ongoing research in the field of Mobile Ad-hoc Networks (MANET) for several different scenarios. Research has focused on topology related challenges such as routing mechanisms or addressing systems, as well as security issues like traceability of radio communication or encryption. In addition, there are very specific research interests such as the effects of directional antennas for MANETs or optimized transmission techniques for minimal power consumption or range optimization. Unmanned aerial vehicles (UAVs), and unmanned aerial systems (UAS) in general, need wireless systems in order to communicate. Current UAS are very flexible and allow for a wide spectrum of mission profiles by means of utilizing different UAVs, according to the requirements at hand. Each mission poses special needs and requirements on the internal and external UAS communication and special mission scenarios calling for UAV swarms increase the complexity and require specialized communication solutions. UAS have specific needs not provided by the general research, but are, on the other hand, to diversified to make much use of narrowly focused developments; UAS form a sufficiently large research area for application of MANETs to be considered as an independent group with specialized needs worthy of tailored implementations of MANET principles. MANET research has not tackled a general approach to UAS although some sources show specific applications involving UAVS. This work presents some new aspects for the development of of ad-hoc wireless networks for UAVs and UAS and focuses on their specialties and needs. A general framework for MANET development is proposed. Furthermore, the proposed specific evaluation scenarios provide for a UAS focused comparison of MANET performance.

Distributed systems like e-commerce and e-market places, peer-to-peer networks, social networks, and mobile ad hoc networks require cooperation among the participating entities to guarantee the formation and sustained existence of network services. The reliability of interactions among anonymous entities is a significant issue in such environments. The distributed entities establish connections to interact with others, which may include selfish and misbehaving entities and result in bad experiences. Therefore, trustworthiness evaluation using trust management techniques has become a significant issue in securing these environments to allow entities decide on the reliability and trustworthiness of other entities, besides it helps coping with defection problems and stimulating entities to cooperate. Recent models on evaluating trustworthiness in distributed systems have heavily focused on assessing trustworthiness of entities and isolate misbehaviours based on single trust metrics. Less effort has been put on the investigation of the subjective nature and differences in the way trustworthiness is perceived to produce a composite multidimensional trust metrics to overcome the limitation of considering single trust metric. In the light of this context, this thesis concerns the evaluation of entities’ trustworthiness by the design and investigation of trust metrics that are computed using multiple properties of trust and considering environment. Based on the concept of probabilistic theory of trust management technique, this thesis models trust systems and designs cooperation techniques to evaluate trustworthiness in mobile ad hoc networks (MANETs). A recommendation based trust model with multi-parameters filtering algorithm, and multidimensional metric based on social and QoS trust model are proposed to secure MANETs. Effectiveness of each of these models in evaluating trustworthiness and discovering misbehaving nodes prior to interactions, as well as their influence on the network performance has been investigated. The results of investigating both the trustworthiness evaluation and the network performance are promising.

The increasing growth of mobile devices in the whole world, and the forecasts for the coming years has been indicated by several reports. Nonetheless, this need for ubiquitous collaboration has brought new possibilities and challenges to the scientific community. Mobile Ad hoc Networks (MANETs) emerges in this scenario allowing devices to interconnect autonomously, without the need of a fixed infrastructure, in order to provide communication and information services. Due to such decentralization and the natural constraints of mobile devices, it remains, to this day, a challenge to provide efficient routing for MANETs. In this dissertation we propose new routing enhancements based on policies for MANETs running the HTR protocol. We consider the role(s) a user associated to a device performs within an organization. Hence our policies can guide the routing based on these roles. With this scheme we improve communication according to different business needs and scenario requirements. To this end, we propose a set of policies that affects the routing behavior and present four case studies to present each policy. Then we analyze two policies in terms of end-to-end delay, and nodes’ lifetime. Through simulation we evaluate these metrics while varying parameters such as the amount of nodes participating in the network, the mobility characteristics, and the number of traffic sources. Our results show that it is possible to achieve these goals without causing great impact on the average end-to-end delay and energy consumption, two important metrics in any MANET evaluation. We explore the results in several scenarios and detail our findings, which can provide a different perspective for future MANET applications. / Submitted by João Arthur Martins (joao.arthur@ufpe.br) on 2015-03-10T18:42:15Z No. of bitstreams: 2 Dissertação Gabriela Coutinho.pdf: 1701782 bytes, checksum: 113328c2efdd1ba97f7a237d03cab574 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) / Made available in DSpace on 2015-03-11T17:46:06Z (GMT). No. of bitstreams: 2 Dissertação Gabriela Coutinho.pdf: 1701782 bytes, checksum: 113328c2efdd1ba97f7a237d03cab574 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2013-09-13 / O crescimento das vendas de aparelhos móveis em todo o mundo, bem como as previsões para os próximos anos são apontadas em diversos relatórios. No entanto, essa necessidade de colaboração ubíqua trouxe novas possibilidades e desafios para a comunidade científica. Redes móveis ad hoc (Mobile Ad hoc Networks - MANETs) surgem diante deste cenário e permite que dispositivos se comuniquem de forma autônoma, sem a necessidade de uma infraestrutura predefinida para fornecer comunicação e serviços. Porém, essa descentralização junto com as restrições naturais dos dispositivos móveis, proporcionar roteamento eficiente para MANETs permanece um desafio. Este trabalho propõe novas melhorias para o roteamento em MANETs que utilizam o protocolo HTR. Também considera o papel que usuários associados aos dispositivos desempenham dentro de uma organização. Desta forma, as políticas desenvolvidas podem guiar o roteamento também com base nestes papéis. Com este esquema, é possível melhorar a comunicação de acordo com necessidades de negócio e requerimentos de cenário. Para este fim, esta dissertação propõe um conjunto de políticas que afetam o comportamento do roteamento e analisa os impactos em termos de atraso, energia gasta e tempo de vida dos nós. Através de simulações, essas métricas são avaliadas também com variação de parâmetros como a quantidade de nós que participam da simulação, as características de mobilidade e o número de fontes de tráfego. Resultados mostram que é possível atingir esses objetivos sem causar grande impacto negativo no atraso fim a fim e no consumo de energia, duas métricas importantes em avaliações de redes MANET. Nós exploramos esses resultados em diversos cenários e detalhamos nossas descobertas, que podem servir como uma perspectiva diferente para futuras aplicações de redes MANET.

With the constant development of wireless technologies, the usageof wireless devices tends to increase even more in the future.Wireless multi-hop networks (WMNs) have emerged as a keytechnology to numerous potential scenarios, ranging from disasterrecovery to wireless broadband internet access. The distributedarchitecture of WMNs enables nodes to cooperatively relay othernode's packets. Because of their advantages over other wirelessnetworks, WMNs are undergoing rapid progress and inspiringnumerous applications. However, many technical issues still existin this field. In this thesis we investigate how Voice over IP(VoIP) and peer-to-peer (P2P) application are influenced bywireless multi-hop network characteristics and how to optimizethem in order to provide scalable communication.We first consider the deployment of VoIP service in wirelessmulti-hop networks, by using the Session Initiation Protocol (SIP)architecture. Our investigation shows that the centralized SIParchitecture imposes several challenges when deployed in thedecentralized wireless multi-hop environment. We find that VoIPquality metrics are severely degraded as the traffic and number ofmultiple hops to the gateway increase. In the context ofscalability, we further propose four alternative approaches whichavoid current limitations.In the second part of this thesis we tackle the network capacityproblem while providing scalable VoIP service over wirelessmulti-hop networks. The performance evaluation shows the influenceof intra and inter-flow interference in channel utilization, whichdirect impacts the VoIP capacity. In order to avoid the small VoIPpacket overhead, we propose a new adaptive hop-by-hop packetaggregation scheme based on wireless link characteristics. Ourperformance evaluation shows that the proposed scheme can increasethe VoIP capacity by a two-fold gain.The study of peer-to-peer applicability over wireless multi-hopnetworks is another important contribution. A resource lookupapplication is realized through structured P2P overlay. We showthat due to several reasons, such as characteristics of wirelesslinks, multi-hop forwarding operation, and structured P2Pmanagement traffic aggressiveness the performance of traditionalP2P applications is rather low in wireless multi-hop environments.Therefore, we suggested that a trade-off between the P2P lookupefficiency and the P2P management traffic overhead can be achievedwhile maintaining the overlay network consistency in wirelessmulti-hop networks.

[pt] Uma rede móvel ad hoc consiste de uma coleção de dispositivos computacionais portáteis, equipados com uma interface de comunicação sem fio, com uma distribuição arbitrária e dinâmica no espaço, e onde cada host também serve de roteador para os demais hosts, descobrindo e mantendo rotas multi-hop entre os hosts. De uma forma geral, os protocolos para redes móveis ad hoc são mais complexos do que os protocolos para as redes fixas, devido à várias características destas redes, como por exemplo, a topologia dinâmica, a interferência mútua, o acesso compartilhado e a largura de banda restrita dos enlaces sem fio, bem como a operação com energia restrita e menor quantidade de recursos disponíveis nos hosts móveis. Um grande foco da pesquisa em redes móveis ad hoc tem sido o desenvolvimento, a análise e a comparação de protocolos de roteamento. Por isto, existe a demanda por ambientes para a prototipação rápida, a simulação e a depuração de protocolos de roteamento (e de outras camadas) para este tipo de redes. Preferencialmente estes ambientes devem ser flexíveis, ser simples de usar, e permitir definir vários níveis de abstrações para descrever as características físicas da rede móvel, tais como o padrão de mobilidade, os enlaces sem fio, consumo de energia, etc. Esta dissertação trata do projeto e implementação de um framework para a simulação de redes móveis ad hoc que visa facilitar a criação de ambientes para prototipação, teste, análise de desempenho e complexidade de protocolos para este tipo de redes. / [en] A mobile ad hoc network consists of a set of portable computational devices, equipped with a wireless communication interface, that are randomly and dynamically distributed in space, and where each host serves as a router for the other hosts by discovering and maintaining multi-hop routes among the hosts. In general, protocols for mobile ad hoc networks are more complex than equivalent protocols for static networks, due to several properties of such networks, such as its dynamic topology, the mutual interference, concurrent access and smaller communication bandwidth of the wireless links, as well as, operation with restricted amount of energy, and scarce resources of the mobile devices. A main focus of research in mobile ad hoc networks has been the development, analysis and comparison of routing protocols for such networks. Therefore, there is some demand for environments that facilitate the rapid prototyping, the simulation and the debugging of protocols at the network and other layers for such networks. These environments should preferably be flexible, easy to use, and allow for the definition of different levels of abstractions for modeling the main characteristics of the mobile network, such as the pattern of mobility, the wireless links, the energy consumption, etc. This thesis describes the design and implementation of a framework for the simulation of mobile ad hoc networks, which aims at supporting the development of concrete simulation environments for prototyping, testing and doing the complexity and performance analysis of protocols for such networks.

Mobile Ad hoc Networks (MANETs) are re-emerging as a popular networking facility for wireless device users. A growing number of diversified applications are now accessible via wireless devices. The different applications may have different Quality of Service (QoS) requirements, which may better be satisfied by using different routing methods or metric types. Existing ad hoc network routing solutions do not consider various application-level requirements when making a routing decision. They typically make routing decisions based upon limited information acquired at the network layer. Most of the existing routing protocols make use of a single routing metric. Using a single metric type and/or information, only acquired at the network layer may not be able to accommodate different QoS requirements, imposed by diversified user-level applications or application-level data types.The aim of this thesis is to design an efficient routing function for ad hoc networks while at the same time satisfying users‟ and/or applications‟ QoS and security requirements. To achieve this, the thesis investigates and specifies routing requirements that could best support application-level QoS and security requirements in MANETs. It also investigates and critically analyses the state of the art in MANET routing, and the mechanisms used for protecting the routing functions. To overcome the weaknesses and advance the state of the art in MANET routing, this thesis proposes two major solutions. The first solution is the Secure ETX (SETX) routing protocol. It is a secure routing solution that can provide routing functions efficiently in malicious MANET environment. The SETX protocol provides a security mechanism to counter black hole attacks in MANETs on the ETX metric acquisition process. Simulation studies have been carried out and discussed in the thesis. Simulation results show that the SETX protocol can provide a marked improvement in network performances in the presence of black hole attacks, and it can do so with a negligible level of additional overhead.The second solution is a novel routing decision making called the Flexible Routing Decision (FRD) framework. The FRD framework supports routing decision making by using multiple metric types (i.e. multi-criteria routing decision making) and uses a cross-layer approach to support application-level QoS requirements. This allows users to use different routing metrics types, making the most appropriate routing decision for a given application. To accommodate the diversified application-level QoS requirements, multiple routing metric types have been identified and interpreted in the FRD framework design. The FRD framework has overcome some weaknesses exhibited by existing single metric routing decision making, used in MANETs. The performance of a routing decision making of FRD is also evaluated using NS2 simulation package. Simulation results demonstrate that the FRD framework outperforms the existing routing decision making methods.

[EN] In recent years, advances in wireless technologies and improved sensing and computational capabilities have led to a gradual transition towards Intelligent Transportation Systems (ITS) and related applications. These applications aim at improving road safety, provide smart navigation, and eco-friendly driving. Vehicular Ad hoc Networks (VANETs) provide a communication structure for ITS by equipping cars with advanced sensors and communication devices that enable a direct exchange of information between vehicles. Different types of ITS applications rely on two types of messages: periodic beacons and event-driven messages. Beacons include information such as geographical location, speed, and acceleration, and they are only disseminated to a close neighborhood. Differently from beacons, event-driven messages are only generated when a critical event of general interest occurs, and it is spread within a specific target area for the duration of the event. The reliability of information exchange is one of the main issues for vehicularcommunications since the safety of people on the road is directly related to the effectiveness of these transmissions. A Medium Access Control (MAC) protocol must guarantee reliable beacon broadcasting within deadline bounds to all vehicles in the neighbourhood, thereby providing them timely notifications about unsafe driving conditions or other hazardous events. Moreover, infotainment and comfort applications require reliable unicast transmissions that must be taken into account. However, high node mobility, highly dynamic topology, and lack of a central control unit, are issues that make the design of a reliable MAC protocol for vehicular environments a very difficult and challenging task, especially when efficient broadcasting strategies are required. The IEEE 802.11p MAC protocol, an approved amendment to the IEEE 802.11 standard, is a random access protocol that is unable to provide guaranteed delay bounds with sufficient reliability in vehicular scenarios, especially under high channel usage. This problem is particularly serious when implementing (semi-) automated driving applications such as platooning, where inter-vehicle spacing is drastically reduced, and the control loop that manages and maintains the platoon requires frequent, timely and reliable exchange of status information (beacons). In this thesis novel protocols compatible with the IEEE 802.11 and 802.11p standards are proposed in order to optimally adjust the contention window size for unicast applications in Mobile Ad hoc Networks (MANETs) and VANETs. Experimental tests comparing our proposals to existing solutions show that the former are able to improve the packet delivery ratio and the average end-to-end delay for unicast applications. Concerning efficient message diffusion (broadcast) in VANET environments, we proposed token-based MAC solutions to improve the performance achieved by existing 802.11p driving safety applications in different vehicular environments, including highway, urban, and platooning scenarios. Experimental results show that the proposed solutions clearly outperform 802.11p when delay-bounded beacons and event notifications must be delivered. / [ES] Recientemente, los avances en las tecnologías inalámbricas y las mejoras en términos de capacidades de sensorización y computación de los dispositivos electrónicos, han dado lugar a una transición gradual hacia servicios y aplicaciones de los Sistemas Inteligentes de Transporte (ITS). Estas aplicaciones tienen como objetivo mejorar la seguridad vial, proporcionar una navegación inteligente, y promover la conducción eco-eficiente. Las redes vehiculares ad hoc (VANETs) proporcionan una infraestructura de comunicaciones para ITS al equipar los coches con sensores avanzados y dispositivos de comunicación que permiten el intercambio directo de información entre vehículos. Los diferentes tipos de aplicaciones ITS se basan en dos tipos de mensajes: mensajes periódicos conocidos como beacons y mensajes asociados a eventos. Los mensajes periódicos incluyen información relativa a la ubicación geográfica, la velocidad y la aceleración, entre otros, y sólo son distribuidos entre los vehículos vecinos. A diferencia de estos beacons, los mensajes asociados a eventos sólo se generan cuando se produce un evento crítico de interés general, el cual se propaga dentro del área de interés de dicho evento y mientras éste siga activo. La fiabilidad del intercambio de información es uno de los principales problemas para las comunicaciones vehiculares, debido principalmente a que las aplicaciones de seguridad dependen directamente de la eficacia de estas transmisiones. Un protocolo de Control de Acceso al Medio (MAC) debe garantizar la difusión fiable de información a todos los vehículos vecinos dentro de unos límites máximos de retardo, proporcionándoles las notificaciones oportunas respecto a condiciones de conducción inseguras y otros eventos peligrosos. Por otra parte, las aplicaciones de información y entretenimiento, así como las aplicaciones orientadas al confort, también requieren transmisiones fiables extremoa-extremo. Sin embargo, la alta movilidad de los vehículos, la variabilidad de la topología, así como la falta de una unidad central de control, son factores que hacen que el diseño de un protocolo MAC fiable para entornos vehiculares sea una tarea especialmente compleja, especialmente cuando son necesarias estrategias de difusión eficientes. El protocolo MAC IEEE 802.11p, una modificación ya aprobada al estándar IEEE 802.11 original para entornos de comunicación vehiculares, es un protocolo de acceso que no es capaz de garantizar unos límites de retardo con la fiabilidad necesaria para estos entornos, especialmente en escenarios de alta utilización del canal inalámbrico. Este problema es particularmente importante a la hora de implementar aplicaciones de conducción (semi-)automática, como el caso de grupos de vehículos donde la separación entre vehículos se reduce drásticamente, y el sistema de control que gestiona y mantiene el grupo requiere de un intercambio frecuente de información fiable y acotado en retardo. En esta tesis se proponen nuevos protocolos MAC compatibles con los estándares IEEE 802.11 y 802.11p basados en el ajuste del tamaño de la ventana de contención para aplicaciones unicast en rede MANETs y VANETs. Los resultados experimentales obtenidos comparando nuestras propuestas con las soluciones existentes muestran que los protocolos propuestos son capaces de mejorar la tasa de entrega de paquetes y el retardo medio extremo-a-extremo para aplicaciones unicast. En lo que respecta a la difusión eficiente de mensajes broadcast en entornos VANET, se han propuesto soluciones MAC basadas en el uso de tokens que mejoran las prestaciones de aplicaciones de conducción segura basadas en el estándar 802.11p, tanto en autopistas, zonas urbanas, y escenarios con grupos de vehículos. Los resultados experimentales muestran que las soluciones propuestas superan claramente al protocolo 802.11p cuando es necesario entregar mensajes y notificaciones de eventos con restricc / [CAT] Recentment, els avan en les tecnologies sense fils i les millores en termes de capacitats de sensorització i computació dels dispositius electrònics, han donat lloc a una transició gradual cap a serveis i aplicacions dels sistemes intelligents de transport (ITS). Aquestes aplicacions tenen com a objectiu millorar la seguretat vial, proporcionar una navegació intelligent, i promoure la conducció ecoeficient. Les xarxes vehiculars ad hoc (VANET) proporcionen una infraestructura de comunicacions per a ITS, ja que equipen els cotxes amb sensors avançats i dispositius de comunicació que permeten l'intercanvi directe d'informació entre vehicles. Els diversos tipus d'aplicacions ITS es basen en dos classes de missatges: missatges periòdics coneguts com a beacons i missatges associats a esdeveniments. Els missatges periòdics inclouen informació relativa a la ubicació geogràfica, la velocitat i l'acceleració, entre uns altres, i només són distribuïts entre els vehicles veïns. A diferència d'aquests beacons, els missatges associats a esdeveniments només es generen quan es produeix un esdeveniment crític d'interès general, el qual es propaga dins de l àrea d'interès d'aquest esdeveniment i mentre aquest seguisca actiu. La fiabilitat de l'intercanvi d'informació és un dels principals problemes per a les comunicacions vehicular, principalment perquè les aplicacions de seguretat depenen directament de l'eficàcia d'aquestes transmissions. Un protocol de control d'accés al medi (MAC) ha de garantir la difusió fiable d'informació a tots els vehicles veïns dins d'uns límits màxims de retard, i proporcionar-los les notificacions oportunes respecte a condicions de conducció insegures i altres esdeveniments perillosos. D'altra banda, les aplicacions d'informació i entreteniment, com també les aplicacions orientades al confort, també requereixen transmissions fiables extrema-extrem. No obstant això, l'alta mobilitat dels vehicles, la variabilitat de la topologia, i la falta d'una unitat central de control, són factors que fan que el disseny d'un protocol MAC fiable per a entorns vehiculars siga una tasca especialment complexa, especialment quan són necessàries estratègies de difusió eficients. El protocol MAC IEEE 802.11p, una modificació ja aprovada a l'estàndard IEEE 802.11 original per a entorns de comunicació vehiculars, és un protocol d'accés que no és capa garantir uns límits de retard amb la fiabilitat necessària per a aquests entorns, especialment en escenaris d'alta utilització del canal sense fil. Aquest problema és particularment important a l'hora d'implementar aplicacions de conducció (semi)automàtica, com el cas de grups de vehicles en què la separació entre vehicles es redueix dràsticament, i el sistema de control que gestiona i manté el grup requereix un intercanvi freqüent d'informació fiable i delimitat en retard. En aquesta tesi es proposen nous protocols MAC compatibles amb els estàndards IEEE 802.11 i 802.11p basats en l'ajust de les dimensions de la finestra de contenció per a aplicacions unicast en xarxes MANET i VANET. Els resultats experimentals obtinguts comparant les nostres propostes amb les solucions existents mostren que els protocols proposats són capa de millorar la taxa de lliurament de paquets i el retard mitjà extrem-a-extrem per a aplicacions unicast. Pel que fa a la difusió eficient de missatges broadcast en entorns VANET, s'han proposat solucions MAC basades en l'ús de tokens que milloren les prestacions d'aplicacions de conducció segura basades en l'estàndard 802.11p, tant en autopistes, zones urbanes, i escenaris amb grups de vehicles. Els resultats experimentals mostren que les solucions proposades superen clarament el protocol 802.11p quan cal lliurar missatges i notificacions d'esdeveniments amb restriccions de latència. / Balador, A. (2016). Design and Evaluation of Efficient Medium Access Control Solutions for Vehicular Environments [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/64073 / TESIS

[EN] This thesis dissertation tackles the problem concerning provision of video streaming services over mobile wireless ad hoc networks. Such networks are characterized by their versatility and flexibility, features that make them particularly suited to be used in many scenarios. However, some limitations inherited of the wireless channel and the mobility of the nodes make difficult to guarantee certain degree of quality of service, which is a required condition to the multimedia applications. Furthermore, with the massive demand of video content, it has become very necessary for mobile ad hoc networks to have an efficient routing and quality of services mechanisms to support this traffic. This is because video streaming services require network to provide sufficient bandwidth and an upper bound in delay, jitter and loss rate. Consequently, traditional best-effort protocols are not adequate. The main contribution of this thesis is the development of a comprehensive routing protocol that has a feedback scheme in order to provide information to the application about the network conditions. This protocol has a cross-layer architecture and it incorporates three important enhancements. Firstly, a new route recovery strategy, which provides a mechanism to detect the link failures in a route and re-establish the connections taking into account the conditions of quality of service that have been established during the previous route discovery phase. Secondly, an algorithm for the estimation of the available bandwidth along the route, information that is sent to application layer in order to apply an adaptation procedure that adjusts the bit rate of the video source. This rate-adaptive strategy is performed exploiting the layered scheme of the scalable video coding. In particular, the adaptive method removes, from the scalable video stream, those layers that could not be efficiently supported by network since their bitrates exceed the available bandwidth. The third main feature of the proposed routing protocol is a gateway discovery algorithm to improve the interconnectivity between mobile ad hoc networks and infrastructure-based networks. This algorithm incorporates available bandwidth as a metric during the gateway selection and a dynamic adaptation of some operational parameters such as the size of the proactive area and the frequency of the advertisement messages. Additionally, in order to solve the lack of a software tool to simulate rate-adaptive transmission of scalable video, a new simulation framework had be implemented. This simulation tool is an open source software freely available and, thus, it represents other contribution of this thesis. The results reveal performance improvements in terms of packet delay, dropped packets and the number of link failures while a more efficient use of the available bandwidth is obtained. In terms of video transmission, the results prove that the combined use of the proposed protocol and the scalable video coding provides an efficient platform for supporting rate-adaptive video streaming over mobile ad hoc networks. / [ES] Esta tesis aborda los problemas relacionados con los servicios de video en modo streaming sobre las redes móviles ad hoc. Este tipo de redes se caracterizan por su versatilidad y flexibilidad, lo cual las hace especialmente adecuadas para ser utilizadas en diversos escenarios. Sin embargo, algunas limitaciones inherentes a los enlaces inalámbricos y a la movilidad de los nodos, hace difícil garantizar cierto nivel de calidad de servicio, lo cual es una condición necesaria para el transporte de flujos multimedia. Además, con la masiva demanda de videos desde los dispositivos móviles, hace aún más necesario asegurar un encaminamiento eficiente y un cierto nivel de calidad de servicio en las redes móviles ad hoc. Por lo tanto, los tradicionales protocolos que funcionan bajo el modelo del "mejor esfuerzo" no son adecuados. Esto se debe principalmente a que las aplicaciones multimedia necesitan que la red asegure suficiente ancho de banda y unos valores máximos de retardo, jitter, y tasa de pérdidas. La principal contribución de esta tesis es el desarrollo de un protocolo de encaminamiento que contiene un esquema de realimentación que le permite informar a la aplicación sobre las condiciones de la red. Este protocolo tiene una arquitectura cross-layer e incorpora tres importantes mejoras. Primero, una nueva estrategia de mantenimiento y recuperación de rutas que provee mecanismos para detectar los fallos de conectividad y el posterior re-establecimiento de las conexiones, teniendo en cuenta las condiciones de calidad de servicio que fueron establecidas durante la etapa inicial del descubrimiento de las rutas. Segundo, un algoritmo para la estimación del ancho de banda disponible a lo largo de la ruta, información que es enviada a la capa de aplicación para aplicar un proceso de adaptación que ajusta la tasa de envío de datos de la fuente. Esta estrategia adaptativa de la tasa aprovecha el esquema por capas de la codificación escalable de video. En particular, el método adaptativo elimina del flujo de video escalable, aquellas capas que no pueden ser transmitidas por la red ya que su tasa de bits supera el ancho de banda disponible. La tercera mejora incluida en el protocolo propuesto es un algoritmo de descubrimiento de gateways para mejorar la interconectividad entre las redes móviles ad hoc y las redes basadas en infraestructura. Dicho algoritmo utiliza el ancho de banda disponible para seleccionar el mejor gateway, así mismo, realiza una adaptación dinámica de algunos parámetros operacionales como el alcance y la frecuencia de los mensajes anuncio. Adicionalmente, ha sido desarrollada una herramienta software para simular la transmisión adaptativa de video escalable sobre redes móviles ad hoc. Esta herramienta de simulación es un software de código abierto y constituye otra contribución más de esta tesis. Los resultados muestran mejoras en el funcionamiento de las redes relacionadas con el retardo, la tasa de pérdidas de paquetes y el número de fallos en la conectividad. Simultáneamente, se obtiene un uso más eficiente del ancho de banda. En relación a la calidad del video transmitido, los resultados demuestran que la utilización del protocolo propuesto junto con la codificación de video escalable, provee un eficiente sistema para la transmisión adaptativa de video escalable sobre redes móviles ad hoc. / [CAT] Aquesta tesi aborda els problemes relacionats amb els serveis de vídeo en mode streaming sobre les xarxes mòbils ad hoc. Aquest tipus de xarxes es caracteritzen per la seva versatilitat i flexibilitat, la qual cosa les fa especialment adequades per a ser utilitzades en diversos escenaris. No obstant això, algunes limitacions inherents als enllaços sense fils i a la mobilitat dels nodes, fa difícil garantir cert nivell de qualitat de servei, cosa que és una condició necessària per al transport de fluxos multimèdia. A més, amb la massiva demanda de vídeos des dels dispositius mòbils, fa encara més necessari assegurar un encaminament eficient i un cert nivell de qualitat de servei en les xarxes mòbils ad hoc. Per tant, els tradicionals protocols que funcionen sota el model del "millor esforç" no són adequats. Això es deu principalment al fet que les aplicacions multimèdia necessiten que la xarxa asseguri suficient ample de banda i uns valors màxims de retard, jitter, i taxa de pèrdues. La principal contribució d'aquesta tesi és el desenvolupament d'un protocol d'encaminament que conté un esquema de realimentació que li permet informar l'aplicació sobre les condicions de la xarxa. Aquest protocol té una arquitectura cross-layer i incorpora tres importants millores. Primer, una nova estratègia de manteniment i recuperació de rutes que proveeix mecanismes per detectar les fallades de connectivitat i el posterior re-establiment de les connexions, tenint en compte les condicions de qualitat de servei que van ser establertes durant l'etapa inicial del descobriment de les rutes. Segon, un algoritme per a l'estimació de l'ample de banda disponible al llarg de la ruta, informació que és enviada a la capa d'aplicació per aplicar un procés d'adaptació que ajusta la taxa d'enviament de dades de la font. Aquesta estratègia adaptativa de la taxa aprofita l'esquema per capes de la codificació escalable de vídeo. En particular, el mètode adaptatiu elimina del flux de vídeo escalable aquelles capes que no poden ser transmeses per la xarxa ja que la seva taxa de bits supera l'ample de banda disponible. La tercera millora inclosa en el protocol proposat és un algoritme de descobriment de gateways per millorar la interconnectivitat entre les xarxes mòbils ad hoc i les xarxes basades en infraestructura. Aquest algoritme utilitza l'ample de banda disponible per seleccionar el millor gateway, així mateix, realitza una adaptació dinàmica d'alguns paràmetres operacionals com l'abast i la freqüència dels missatges anunci. Addicionalment, ha estat desenvolupada una eina programari per a simular la transmissió adaptativa de vídeo escalable sobre xarxes mòbils ad hoc. Aquesta eina de simulació és un programari de codi obert i constitueix una altra contribució més d'aquesta tesi. Els resultats mostren millores en el funcionament de les xarxes relacionades amb el retard, la taxa de pèrdues de paquets i el nombre de fallades en la connectivitat. Simultàniament, se n'obté un ús més eficient de l'ample de banda. En relació a la qualitat del vídeo transmès, els resultats demostren que la utilització del protocol proposat juntament amb la codificació de vídeo escalable, proveeix un eficient sistema per a la transmissió adaptativa de vídeo escalable sobre xarxes mòbils ad hoc. / Castellanos Hernández, WE. (2015). Quality of Service Routing and Mechanisms for Improving Video Streaming over Mobile Wireless Ad hoc Networks [Tesis doctoral]. Editorial Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/53238 / TESIS

According to a Gartner Group (www.gartner.com) report in September 2008, the worldwide telecommunications market is on pace to reach $2 trillion in 2008. Gartner predicts that by 2012, the ratio of mobile to fixed connections will exceed 4-to-1. The North American mobile data market grew to 141.1 million connections in 2007, with a compound annual growth rate of 41.7 percent. It is believed that a large portion will be ad hoc and multi-hop connections, which will open many opportunities for Mobile Ad hoc NETwork (MANET) applications and Wireless Mesh Network (WMN) applications. A MANET is a self-organizing multi-hop wireless network where all nodes participate in the routing and data forwarding process. Such a network can be easily deployed in situations where no base station is available, and a network must be build spontaneously. In applications such as battlefield communications, national crises, disaster recovery, and sensor deployment, a wired network is not available and ad hoc networks provide the only feasible means of communications and information access. Ad hoc networks have also become commonplace for gaming, conferencing, electronic classrooms, and particularly vehicle-to-vehicle communications. A Wireless mash network (WMN) is collection of mesh clients and mesh nodes (routers), with mesh nodes forming the backbone of the network and providing connection to the Internet and other network. Their rapid deployment and ease of maintenance are suitable for on-demand network such as disaster recovery, homeland security, convention centers, hard-to-wire buildings and unfriendly terrains. One important problem with MANET is the routing protocol that needs to work well not just with a small network, but also sustain efficiency and scalability as the network gets expanded and the application transmits data in greater volume. In such an environment, mobility, channel error, and congestion are the main causes for packet loss. Due to mobility of mobile hosts, addressing frequent and unpredictable topology changes is fundamental to MANET research. Two general approaches have been considered: connection-oriented approach and connectionless-oriented approach. In the former, the emphasis is on how to reconnect quickly with low overhead when a broken link occurs. Examples of this approach includes includes [5], [9], [10], [16], [26], [28], [29], [34], [44], and [45]. In contrast, connectionless-oriented approach focuses on minimizing the occurrence of broken links. We proposed one such scheme called Connectionless Approach (CLA) and . In CLA, the network area is divided into non-overlapping grid cells, each serving as a virtual router. Any physical router (i.e., mobile host), currently inside a virtual router, can help forward the data packet to the next virtual router along the virtual link. This process is repeated until the packet reaches its final destination. Since a virtual link is based on virtual routers which do not move, it is much more robust than physical links used in the connection-oriented techniques. Simulation results in our previous works and , based on GloMoSim , indicate that CLA performs significantly better than connection-oriented techniques (i.e., AODV, DSR, LAR, GRID, TMNR, and GPSR). The contribution of this work consists of investigating and developing new Connectionless-Oriented Approach for Mobile Ad Hoc Network. Two of the greatest impacts of this research are as follows. First, the new approach is targeted towards robustly support high mobility and large scale environment which has been adapted for vehicle-to-vehicle environment in . Second, the detailed simulations which compare eight representative routing protocols, namely AODV, DSR, LAR, GRID, TMNR, GPSR, CBF, and CLA, under high-mobility environments. As many important emergent applications of the technology involved high-mobility nodes, very little is known about the existing routing methods perform relative to each other in high-mobility environments. The simulation results provide insight into ad hoc routing protocols and offer guidelines for mobile ad hoc network applications. Next, we enhanced and extend the connectionless-oriented approach. The current connectionless-oriented approach, however, may suffer from packet drops since traffic congestion is not considered in the packet forwarding policy. We address this weakness by considering the connectionless-oriented approach with a collision avoidance routing technique. After that, we investigate techniques to enforce collaboration among mobile devices in supporting the virtual router functionality. Many works have been published to combat such problem - misbehaving nodes are detected and a routing algorithm is employed to avoid and penalize misbehaving nodes. These techniques, however, cannot be applied to the connectionless-oriented approach since any node in the general direction towards the destination node can potentially help forward the data packets. To address the security and cooperation issues for connectionless-oriented approach, we introduce a cooperation enforcement technique called 3CE (3-Counter Enforcement). In addition, wireless mesh networks have become increasingly popular in recent years. Wireless mash network (WMNs) are collection of mesh clients and mesh nodes (routers), with mesh nodes forming the backbone of the network and providing connection to the Internet and other network. We propose a paradigm that combines virtual routers and mesh nodes to create a hybrid network call VR-Mesh Network. This hybrid network can reduce number of mesh node needed without decrease the performance of the network.