While there has always been a tremendous demand for streaming video over Wireless networks, the nature of the application still presents some challenging issues. These applications that transmit coded video sequence data over best-effort networks like the Internet, the application must cope with the changing network behaviour; especially, the source encoder rate should be controlled based on feedback from a channel estimator that explores the network intermittently. The arrival of powerful video compression techniques such as H.264, which advance in networking and telecommunications, opened up a whole new frontier for multimedia communications. The aim of this research is to transmit the H.264 coded video frames in the wireless network with maximum reliability and in a very efficient manner. When the H.264 encoded video sequences are to be transmitted through wireless network, it faces major difficulties in reaching the destination. The characteristics of H.264 video coded sequences are studied fully and their capability of transmitting in wireless networks are examined and a new approach called Optimal Packet Fragmentation (OPF) is framed and the H.264 coded sequences are tested in the wireless simulated environment. This research has three major studies involved in it. First part of the research has the study about Long Range Dependence (LRD) and the ways by which the self-similarity can be estimated. For estimating the LRD a few studies are carried out and Wavelet-based estimator is selected for the research because Wavelets incarcerate both time and frequency features in the data and regularly provides a more affluent picture than the classical Fourier analysis. The Wavelet used to estimate the self-similarity by using the variable called Hurst Parameter. Hurst Parameter tells the researcher about how a data can behave inside the transmitted network. This Hurst Parameter should be calculated for a more reliable transmission in the wireless network. The second part of the research deals with MPEG-4 and H.264 encoder. The study is carried out to prove which encoder is superior to the other. We need to know which encoder can provide excellent Quality of Service (QoS) and reliability. This study proves with the help of Hurst parameter that H.264 is superior to MPEG-4. The third part of the study is the vital part in this research; it deals with the H.264 video coded frames that are segmented into optimal packet size in the MAC Layer for an efficient and more reliable transfer in the wireless network. Finally the H.264 encoded video frames incorporated with the Optimal Packet Fragmentation are tested in the NS-2 wireless simulated network. The research proves the superiority of H.264 video encoder and OPF¿s master class.

[ES] Las redes industriales de sensores inalámbricos (IWSN - Industrial Wireless Sensor Networks) tienen una creciente aceptación en los entornos productivos debido a su facilidad de despliegue, bajos costes y eficiencia energética. Sin embargo, la complejidad y precisión que demandan estos entornos requieren que las IWSN implementen mecanismos de calidad de servicio (QoS) que les permitan operar con un alto determinismo. Por esta razón, el estándar IEEE 802.15.4e ha incorporado protocolos de acceso al medio que permiten tener un mayor control sobre las comunicaciones. Estos protocolos permiten asignar de forma predecible y cíclica instantes de tiempo donde los dispositivos de una red pueden transmitir información sin ningún tipo de interferencia o contienda con otros dispositivos de la red. Uno de ellos es el protocolo salto de canal con ranuras de tiempo (TSCH - Time Slotted Channel Hopping) el cual planifica las transmisiones entre los dispositivos en una matriz de dos dimensiones, tiempo y frecuencia. Esta planificación de las transmisiones permite que los dispositivos tengan instantes de tiempo exclusivos para la transmisión, reduciendo así la interferencia y aumentando la fiabilidad de las transmisiones. Sin embargo, este estándar no especifica como asignar los recursos temporales en la planificación TSCH, dando lugar a múltiples soluciones de planificación. Estos enfoques de planificación adquieren una gran relevancia en el actual entorno de la Industria 4.0, donde se busca aumentar de forma masiva la digitalización la interacción y la integración con los diferentes procesos industriales. Por lo tanto, hay una gran diversidad de flujos de información sobre la misma red. Además, al ser flujos de diferentes procesos, también tienen diferentes criticidades, donde deben garantizarse parámetros de QoS como latencia, throughtput, pérdida de paquetes y deadline. Esta creciente demanda de QoS y la diversidad de flujos de tráfico requieren un control estricto y dinámico que no puede lograrse con planificadores convencionales. Por esto, la evolución hacia nuevos paradigmas como las redes definidas por software (SDN - Software Defined Networks) se está convirtiendo en una interesante alternativa para abordar la complejidad de los retos actuales en las IWSN. Estas aceptan un aumento del tráfico de señalización a cambio de ventajas adicionales, tales como: una reducción de la complejidad de los procesos en los nodos, una visión global de todos los elementos de la red y una alta capacidad de reconfiguración. En el desarrollo de esta tesis, se aprovecha el alto nivel de detalle y control que ofrecen las SDN para abordar los complejos desafíos que enfrenta actualmente la adopción de las IWSN en el sector industrial, como la movilidad, la escalabilidad y la garantía de parámetros de QoS. Estos desafíos presentan una complejidad significativa al utilizar los protocolos convencionales; por ello, es necesario implementar un cambio disruptivo que permita superar estas limitaciones de manera sencilla y eficiente. En consecuencia, esta tesis se centra en la investigación y aplicación de mecanismos que permitan adaptar las IWSN al paradigma SDN, así como el desarrollo de protocolos de enrutamiento y planificación TSCH dinámicos que aseguren un alto grado de determinismo y una alta capacidad de adaptación a los cambios en la topología. De esta forma, se garantizan requisitos de QoS independientes para cada tipo de flujo de manera dinámica y con una baja complejidad, incluso en condiciones de movilidad y alta densidad de nodos. / [CA] Les xarxes industrials de sensors sense fils (IWSN - Industrial Wireless Sensor Networks) tenen una creixent acceptació en els entorns productius a causa de la seua facilitat de desplegament, baixos costs i eficiència energètica. No obstant això, la complexitat i precisió que demanden aquests entorns requerixen que les IWSN implementen mecanismes de qualitat de servici (QoS) que els permeten operar amb un alt determinisme. Per aquesta raó, l'estàndard IEEE 802.15.4e ha incorporat protocols d'accés al medi que permeten tindre un major control sobre les comunicacions. Aquest protocols permeten assignar de manera predictible i cíclica instants de temps on els dispositius d'una xarxa poden transmetre informació sense cap mena d'interferència o contesa amb altres dispositius de la xarxa. Un d'ells és el protocol salte de canal amb espais de temps (TSCH - Time Slotted Channel Hopping) el qual planifica les transmissions entre els dispositius en una matriu de dos dimensions, temps i freqüència. Aquesta planificació de les transmissions permet que els dispositius tinguen instants de temps exclusius per a la transmissió, reduint així la interferència i augmentant la fiabilitat de les transmissions. No obstant això, aquest estàndard no especifica com assignar els recursos temporals en la planificació TSCH, donant lloc a múltiples solucions de planificació. Aquest enfocaments de planificació adquireixen una gran rellevància en l'actual entorn de la Indústria 4.0, on es busca augmentar de manera massiva la digitalització, la interacció i la integració amb els diferents processos industrials. Per tant, hi ha una gran diversitat de fluxos d'informació sobre la mateixa xarxa. A més, en ser fluxos de diferents processos, també tenen diferents criticitats, on han de garantir-se paràmetres de QoS com a latència, throughtput, pèrdua de paquets i deadline. Aquesta creixent demanda de QoS i la diversitat de fluxos de trànsit requerixen un control estricte i dinàmic que no pot aconseguir-se amb planificadors convencionals. Per això, l'evolució cap a nous paradigmes com les xarxes definides per programari (SDN - Software Defined Networks) s'està convertint en una interessant alternativa per a abordar la complexitat dels reptes actuals en les IWSN. Aquestes accepten un augment del trànsit de senyalització a canvi d'avantatges addicionals, com ara: una reducció de la complexitat dels processos en els nodes, una visió global de tots els elements de la xarxa i una alta capacitat de reconfiguració. En el desenvolupament d'aquesta tesi, s'aprofita l'alt nivell de detall i control que oferixen les SDN per a abordar els complexos reptes que enfronta actualment l'adopció de les IWSN en el sector industrial, com la mobilitat, l'escalabilitat i la garantia de paràmetres de QoS. Aquests reptes presenten una complexitat significativa en utilitzar els protocols convencionals; per això, és necessari implementar un canvi transgressor que permeta superar aquestes limitacions de manera senzilla i eficient. En conseqüència, aquesta tesi se centra en la investigació i aplicació de mecanismes que permeten adaptar les IWSN al paradigma SDN, així com el desenvolupament de protocols d'encaminament i planificació TSCH dinàmics que asseguren un alt grau de determinisme i una alta capacitat d'adaptació als canvis en la topologia. D'aquesta manera, es garanteixen requisits de QoS independents per a cada tipus de flux de manera dinàmica i amb una baixa complexitat, fins i tot en condicions de mobilitat i alta densitat de nodes. / [EN] Industrial Wireless Sensor Networks (IWSNs) are becoming increasingly popular in production environments due to their ease of deployment, low cost and energy efficiency. However, the complexity and accuracy demanded by these environments require IWSNs to implement quality of service (QoS) mechanisms that allow them to operate with high determinism. For this reason, the IEEE 802.15.4e standard has incorporated medium access protocols that allow for greater control over communications. These protocols enable predictable and cyclic allocation of time slots where devices in a network can transmit information without any interference or contention with other devices in the network. One such protocol is the Time Slotted Channel Hopping (TSCH) protocol, which schedules transmissions between devices using a two-dimensional matrix of time and frequency. This scheduling of transmissions allows devices to have unique time slots for transmission, thereby reducing interference and increasing the reliability of transmissions. However, this standard does not specify how to allocate time resources in TSCH scheduling, leading to multiple scheduling solutions such as centralized scheduling, distributed scheduling, and hybrid scheduling, each with its own advantages and disadvantages. These planning approaches become highly relevant in today's Industry 4.0 environment, where digitisation, interaction and integration with different industrial processes are being massively increased. Therefore, there is a great diversity of information flows over the same network. Moreover, as they are flows of different processes, they also have different criticalities, where QoS parameters such as latency, throughput, packet loss, and deadline must be guaranteed. This increasing QoS demand and the diversity of traffic flows require strict and dynamic control that cannot be achieved with conventional schedulers. Therefore, the evolution towards new paradigms such as Software Defined Networks (SDN) is becoming an interesting alternative to address the complexity of today's challenges in IWSNs. SDNs, in the context of IWSNs, refer to the use of software to manage and control the network, allowing for a more efficient and dynamic allocation of resources. They accept an increase in signalling traffic in exchange for additional benefits, such as: a reduction of the complexity of processes at the nodes, a global view of all network elements and a high reconfiguration capacity. In the development of this thesis, the high level of detail and control offered by SDNs is leveraged to address the complex challenges currently facing the adoption of IWSNs in the industrial sector, such as mobility, scalability and QoS parameter guarantees. These challenges present significant complexity when using conventional protocols; therefore, a disruptive change needs to be implemented to overcome these limitations in a simple and efficient manner. Consequently, this thesis focuses on the investigation and implementation of specific mechanisms, such as dynamic resource allocation and traffic prioritization, to adapt IWSNs to the SDN paradigm. Additionally, new protocols, including dynamic TSCH routing and scheduling protocols, are being developed to ensure a high degree of determinism and a high adaptability to topology changes. In this way, independent QoS requirements for each flow type are guaranteed dynamically and with low complexity, even under conditions of mobility and high node density. / Esta tesis ha sido financiada por las siguientes entidades y proyectos: Instituto Tecnológico de Informática - Proyecto HYPERFACTORY: Arquitecturas, herramientas y servicios para la creación de factorías hiperconectadas: IVACE (IMDEEA/2020/68; IMDEEA/2021/87) / European Commision, IVACE 101007273; IMAMCN/2021/1 - Proyecto: DAIS: Distributed Artificial Intelligent System / Orozco Santos, F. (2024). Diseño y evaluación de redes definidas por software para la orquestación dinámica de calidad de servicio en redes industriales de sensores inalámbricos [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/211263

In order to efficiently utilize the scarce wireless resource as well as keep up with the ever-increasing demand for Quality-of-Service (QoS) of multimedia applications, wireless networks are undergoing rapid development and dramatic changes in the underlying technologies and protocols. The Medium Access Control (MAC) protocol, which coordinates the channel access and data transmission of wireless stations, plays a pivotal role in wireless networks. Performance modelling and analysis has been and continues to be of great theoretical and practical importance in the design and development of wireless networks. This research is devoted to developing efficient and cost-effective analytical tools for the performance analysis and enhancement of MAC protocols in Wireless Local Area Networks (WLANs) under heterogeneous multimedia traffic. To support the MAC-layer QoS in WLANs, the IEEE 802.11e Enhanced Distributed Channel Access (EDCA) protocol has proposed three QoS differentiation schemes in terms of Arbitrary Inter-Frame Space (AIFS), Contention Window (CW), and Transmission Opportunity (TXOP). This research starts with the development of new analytical models for the TXOP scheme specified in the EDCA protocol under Poisson traffic. A dynamic TXOP scheme is then proposed to adjust the TXOP limits according to the status of the transmission queue. Theoretical analysis and simulation experiments show that the proposed dynamic scheme largely improves the performance of TXOP. To evaluate the TXOP scheme in the presence of ii heterogeneous traffic, a versatile analytical model is developed to capture the traffic heterogeneity and model the features of burst transmission. The performance results highlight the importance of taking into account the heterogeneous traffic for the accurate evaluation of the TXOP scheme in wireless multimedia networks. To obtain a thorough and deep understanding of the performance attributes of the EDCA protocol, a comprehensive analytical model is then proposed to accommodate the integration of the three QoS schemes of EDCA in terms of AIFS, CW, and TXOP under Poisson traffic. The performance results show that the TXOP scheme can not only support service differentiation but also improve the network performance, whereas the AIFS and CW schemes provide QoS differentiation only. Moreover, the results demonstrate that the MAC buffer size has considerable impact on the QoS performance of EDCA under Poisson traffic. To investigate the performance of EDCA in wireless multimedia networks, an analytical model is further developed for EDCA under heterogeneous traffic. The performance results demonstrate the significant effects of heterogeneous traffic on the total delay and frame losses of EDCA with different buffer sizes. Finally, an efficient admission control scheme is presented for the IEEE 802.11e WLANs based on analytical modelling and a game-theoretical approach. The admission control scheme can maintain the system operation at an optimal point where the utility of the Access Point (AP) is maximized with the QoS constraints of various users.

Along with playing an ever-increasing role in the integration of other communication networks and expanding in application diversities, the current Internet suffers from serious overuse and congestion bottlenecks. Efficient congestion control is fundamental to ensure the Internet reliability, satisfy the specified Quality-of-Service (QoS) constraints and achieve desirable performance in response to varying application scenarios. Active Queue Management (AQM) is a promising scheme to support end-to-end Transmission Control Protocol (TCP) congestion control because it enables the sender to react appropriately to the real network situation. Analytical performance models are powerful tools which can be adopted to investigate optimal setting of AQM parameters. Among the existing research efforts in this field, however, there is a current lack of analytical models that can be viewed as a cost-effective performance evaluation tool for AQM in the presence of heterogeneous traffic, generated by various network applications. This thesis aims to provide a generic and extensible analytical framework for analyzing AQM congestion control for various traffic types, such as non-bursty Poisson and bursty Markov-Modulated Poisson Process (MMPP) traffic. Specifically, the Markov analytical models are developed for AQM congestion control scheme coupled with queue thresholds and then are adopted to derive expressions for important QoS metrics. The main contributions of this thesis are listed as follows: • Study the queueing systems for modeling AQM scheme subject to single-class and multiple-classes Poisson traffic, respectively. Analyze the effects of the varying threshold, mean traffic arrival rate, service rate and buffer capacity on the key performance metrics. • Propose an analytical model for AQM scheme with single class bursty traffic and investigate how burstiness and correlations affect the performance metrics. The analytical results reveal that high burstiness and correlation can result in significant degradation of AQM performance, such as increased queueing delay and packet loss probability, and reduced throughput and utlization. • Develop an analytical model for a single server queueing system with AQM in the presence of heterogeneous traffic and evaluate the aggregate and marginal performance subject to different threshold values, burstiness degree and correlation. • Conduct stochastic analysis of a single-server system with single-queue and multiple-queues, respectively, for AQM scheme in the presence of multiple priority traffic classes scheduled by the Priority Resume (PR) policy. • Carry out the performance comparison of AQM with PR and First-In First-Out (FIFO) scheme and compare the performance of AQM with single PR priority queue and multiple priority queues, respectively.

The research initiatives addressed in this thesis are geared towards improving the performance of passive optical networks (PONs) through the development of advanced dynamic bandwidth allocation (DBA) protocols. In particular, the aim of the research undertaken is to enhance the quality of service (QoS) offered by standard PONs by means of providing subscribers with service level agreement (SLA) to fulfil applications and associated bandwidth requirements on demand. To accomplish the research objectives, a novel service and bandwidth focused DBA protocol is developed for standard time division multiplexing (TDM), gigabit-capable PONs (GPONs) by flexibly assigning a guaranteed minimum bandwidth to each optical network unit (ONU),terminated at subscribers premises. Modelling and simulation of the developed algorithms have displayed a tenfold enhancement in network performance, showing a superior performance to other published DBA protocols, in terms of mean packet delay. To accomplish protocol optimisation, the ONU upstream transmission properties of TDM-PONs have been further analysed and subsequently the ONU data transfer order in each communication cycle has been dynamically configured to increase the network upstream throughput by overlapping the upstream transmission period with parts of the bandwidth request-allocation process between OLT and ONUs. In addition, with the objective of extending the application of the developed protocol to long-reach PONs by means of reducing the augmented propagation delays due to the network’s extensive reach, the concept of virtual communication cycles has been incorporated into the optimised DBA algorithm. This approach demonstrates comparable transmission efficiency in the context of subscriber throughput and packet delay as in a standard PON but at much longer distances from the network exchange. To overcome the inevitably limited communication capacity of single wavelength TDM protocols and with the transportation of the ever increasing, time-sensitive, multi-media services in mind, a novel multi-wavelength DBA protocol is then developed to be applied to a wavelength division multiplexing–PON. With this protocol, both the downstream and upstream network capacity is dynamically adjusted according to subscribers’ service level and bandwidth demand in each polling cycle as opposed to a fixed upstream network capacity in TDM-PONs. It therefore also demonstrates improved upstream transmission efficiency.

Les réseaux maillés sans fil (RMSF), grâce à leurs caractéristiques avantageuses, sont considérés comme une solution efficace pour le support des services de voix, vidéo et de données dans les réseaux de prochaine génération. Le standard IEEE 802.16-d a spécifié pour les RMSF, à travers son mode maillé, deux mécanismes de planifications de transmission de données; à savoir la planification centralisée et la planification distribuée. Dans ce travail, on a évalué le support de la qualité de service (QdS) du standard en se focalisant sur la planification distribuée. Les problèmes du système dans le support du trafic de voix ont été identifiés. Pour résoudre ces problèmes, on a proposé un protocole pour le support de VoIP (AVSP) en tant qu’extension au standard original pour permettre le support de QdS au VoIP. Nos résultats préliminaires de simulation montrent qu’AVSP offre une bonne amélioration au support de VoIP. / Wireless mesh networks (WMNs), because of their advantageous characteristics, are considered as an effective solution to support voice services, video and data in next generation networks. The IEEE 802.16-d specified for WMNs, through its mesh mode, two mechanisms of scheduling data transmissions; namely centralized scheduling and distributed scheduling. In this work, we evaluated the support of the quality of service (QoS) of the standard by focusing on distributed scheduling. System problems in the support of voice traffic have been identified. To solve these problems, we proposed a protocol for supporting VoIP, called Assisted VoIP Scheduling Protocol (AVSP), as an extension to the original standard to support high QoS to VoIP. Our preliminary simulation results show that AVSP provides a good improvement to support VoIP.

L’émergence de nouvelles applications et de nouveaux services (tels que les applications multimédias, la voix-sur-IP, la télévision-sur-IP, la vidéo-sur-demande, etc.) et le besoin croissant de mobilité des utilisateurs entrainent une demande de bande passante de plus en plus croissante et une difficulté dans sa gestion dans les réseaux cellulaires sans fil (WCNs), causant une dégradation de la qualité de service. Ainsi, dans cette thèse, nous nous intéressons à la gestion des ressources, plus précisément à la bande passante, dans les WCNs. Dans une première partie de la thèse, nous nous concentrons sur la prédiction de la mobilité des utilisateurs des WCNs. Dans ce contexte, nous proposons un modèle de prédiction de la mobilité, relativement précis qui permet de prédire la destination finale ou intermédiaire et, par la suite, les chemins des utilisateurs mobiles vers leur destination prédite. Ce modèle se base sur : (a) les habitudes de l’utilisateur en terme de déplacements (filtrées selon le type de jour et le moment de la journée) ; (b) le déplacement courant de l’utilisateur ; (c) la connaissance de l’utilisateur ; (d) la direction vers une destination estimée ; et (e) la structure spatiale de la zone de déplacement. Les résultats de simulation montrent que ce modèle donne une précision largement meilleure aux approches existantes. Dans la deuxième partie de cette thèse, nous nous intéressons au contrôle d’admission et à la gestion de la bande passante dans les WCNs. En effet, nous proposons une approche de gestion de la bande passante comprenant : (1) une approche d’estimation du temps de transfert intercellulaire prenant en compte la densité de la zone de déplacement en terme d’utilisateurs, les caractéristiques de mobilité des utilisateurs et les feux tricolores ; (2) une approche d’estimation de la bande passante disponible à l’avance dans les cellules prenant en compte les exigences en bande passante et la durée de vie des sessions en cours ; et (3) une approche de réservation passive de bande passante dans les cellules qui seront visitées pour les sessions en cours et de contrôle d’admission des demandes de nouvelles sessions prenant en compte la mobilité des utilisateurs et le comportement des cellules. Les résultats de simulation indiquent que cette approche réduit largement les ruptures abruptes de sessions en cours, offre un taux de refus de nouvelles demandes de connexion acceptable et un taux élevé d’utilisation de la bande passante. Dans la troisième partie de la thèse, nous nous penchons sur la principale limite de la première et deuxième parties de la thèse, à savoir l’évolutivité (selon le nombre d’utilisateurs) et proposons une plateforme qui intègre des modèles de prédiction de mobilité avec des modèles de prédiction de la bande passante disponible. En effet, dans les deux parties précédentes de la thèse, les prédictions de la mobilité sont effectuées pour chaque utilisateur. Ainsi, pour rendre notre proposition de plateforme évolutive, nous proposons des modèles de prédiction de mobilité par groupe d’utilisateurs en nous basant sur : (a) les profils des utilisateurs (c’est-à-dire leur préférence en termes de caractéristiques de route) ; (b) l’état du trafic routier et le comportement des utilisateurs ; et (c) la structure spatiale de la zone de déplacement. Les résultats de simulation montrent que la plateforme proposée améliore la performance du réseau comparée aux plateformes existantes qui proposent des modèles de prédiction de la mobilité par groupe d’utilisateurs pour la réservation de bande passante. / The emergence of new applications and services (e.g., multimedia applications, voice over IP and IPTV) and the growing need for mobility of users cause more and more growth of bandwidth demand and a difficulty of its management in Wireless Cellular Networks (WCNs). In this thesis, we are interested in resources management, specifically the bandwidth, in WCNs. In the first part of the thesis, we study the user mobility prediction that is one of key to guarantee efficient management of available bandwidth. In this context, we propose a relatively accurate mobility prediction model that allows predicting final or intermediate destinations and subsequently mobility paths of mobile users to reach these predicted destinations. This model takes into account (a) user’s habits in terms of movements (filtered according to the type of day and the time of the day); (b) user's current movement; (c) user’s contextual knowledge; (d) direction from current location to estimated destination; and (e) spatial conceptual maps. Simulation results show that the proposed model provides good accuracy compared to existing models in the literature. In the second part of the thesis, we focus on call admission control and bandwidth management in WCNs. Indeed, we propose an efficient bandwidth utilization scheme that consists of three schemes: (1) handoff time estimation scheme that considers navigation zone density in term of users, users’ mobility characteristics and traffic light scheduling; (2) available bandwidth estimation scheme that estimates bandwidth available in the cells that considers required bandwidth and lifetime of ongoing sessions; and (3) passive bandwidth reservation scheme that passively reserves bandwidth in cells expected to be visited by ongoing sessions and call admission control scheme for new call requests that considers the behavior of an individual user and the behavior of cells. Simulation results show that the proposed scheme reduces considerably the handoff call dropping rate while maintaining acceptable new call blocking rate and provides high bandwidth utilization rate. In the third part of the thesis, we focus on the main limitation of the first and second part of the thesis which is the scalability (with the number of users) and propose a framework, together with schemes, that integrates mobility prediction models with bandwidth availability prediction models. Indeed, in the two first contributions of the thesis, mobility prediction schemes process individual user requests. Thus, to make the proposed framework scalable, we propose group-based mobility prediction schemes that predict mobility for a group of users (not only for a single user) based on users’ profiles (i.e., their preference in terms of road characteristics), state of road traffic and users behaviors on roads and spatial conceptual maps. Simulation results show that the proposed framework improves the network performance compared to existing schemes which propose aggregate mobility prediction bandwidth reservation models.

Actuellement, nous constatons une augmentation de demande de services vidéo sur les réseaux P2P. Ces réseaux jouent un rôle primordial dans la transmission de contenus multimédia à grande échelle pour des clients hétérogènes. Cependant, le déploiement de services vidéo temps réel sur les réseaux P2P a suscité un grand nombre de défis dû à l’hétérogénéité des terminaux et des réseaux d’accès, aux caractéristiques dynamiques des pairs, et aux autres problèmes hérités des protocoles TCP/IP, à savoir les pertes de paquets, les délais de transfert et la variation de la bande passante de bout-en-bout. Dans ce contexte, l’objectif de cette thèse est d’analyser les différents problèmes et de proposer un mécanisme de transport vidéo temps réel avec le provisionnement de la qualité de Service (QoS). Ainsi, nous proposons trois contributions majeures. Premièrement, il s’agit d’un mécanisme de streaming vidéo adaptatif permettant de sélectionner les meilleurs pair émetteurs. Ce mécanisme permet de structurer les pairs dans des réseaux overlay hybrides avec une prise en charge des caractéristiques sémantiques du contenu et des caractéristiques physiques du lien de transport. Nous présentons ensuite un mécanisme d’ordonnancement de paquets vidéo combiné à une commutation de pairs et/ou de flux pour assurer un transport lisse. Finalement, une architecture de collaboration entre les applications P2P et les fournisseurs de services / réseaux est proposée pour supporter un contrôle d’admission de flux. / There is an increasing demand for scalable deployment of real-time multimedia streaming applications over Internet. In this context, Peer-to-Peer (P2P) networks are playing an important role for supporting robust and large-scale transmission of multimedia content to heterogeneous clients. However, the deployment of real-time video streaming applications over P2P networks arises lot of challenges due to heterogeneity of terminals and access networks, dynamicity of peers, and other problems inherited from IP network. Real-time streaming applications are very sensitive to packet loss, jitter / transmission delay, and available end-to-end bandwidth. These elements have key importance in QoS provisioning and need extra consideration for smooth delivery of video streaming applications over P2P networks. Beside the abovementioned issues, P2P applications lack of awareness in constructing their overlay topologies and do not have any explicit interaction with service and network providers. This situation leads to inefficient utilization of network resources and may cause potential violation of peering agreements between providers. The aim of this thesis is to analyze these issues and to propose an adaptive real-time transport mechanism for QoS provisioning of Scalable Video Coding (SVC) applications over P2P networks. Our contributions in this dissertation are threefold. First, we propose a hybrid overlay organization mechanism allowing intelligent organization of sender peers based on network-awareness, media- awareness, and quality-awareness. This overlay organization is further used for an appropriate selection of best sender peers, and the efficient switching of peers to ensure a smooth video delivery when any of the sender peers is no more reliable. Second, we propose a packet video scheduling mechanism to assign different parts of the video content to specific peers. Third, we present a service provider driven P2P network framework that enables effective interaction between service / network providers and P2P applications to perform QoS provisioning mechanism for the video streaming.

O segmento das comunicações, já há alguns anos, vem passando por significativas transformações exigindo a interação entre ambientes tecnológicos convergentes heterogêneos, com qualidade na continuidade de serviços, para se manter competitivo, pois é este mercado que exige, constantemente, que mais recursos tecnológicos lhe sejam colocados à disposição. O ineditismo da proposta desenvolvida neste trabalho é a elaboração de um modelo para assegurar a continuidade da qualidade de serviço percebida pelo usuário final através de handover (ou handoff) vertical, o que caracteriza-se como uma necessidade de solução global, isto é, o modelo é genérico e independente da tecnologia, o que permite sua adoção em qualquer ambiente de rede existente aproveitando a capilaridade já disponível das redes legadas. É analisada também a situação na qual um usuário final esteja acessando simultaneamente serviços gerenciados por Provedores de Serviço distintos, o que conduz a duas situações possíveis: a) o usuário está acessando serviços distintos contratados a Provedores de Serviço diferentes; b) o usuário está acessando o mesmo serviço contratado a Provedores de Serviço distintos. Nesta última situação pode surgir a necessidade de disparar um processo de handover exigindo a decisão de qual dos Provedores o executará, de acordo com o SPHDA Service Providers Handover Decision Agreement. A metodologia adotada para o desenvolvido do modelo foi a RM-ODP - Reference Model for Open Distributed Processing, por abranger todos os aspectos técnicos e comerciais necessários à sua construção. / The sector of communications, for some years, has undergone significant changes requiring interaction between converging heterogeneous technology environments, with quality and continuity of services to stay competitive, because this market is that requires constantly more technological resources available. The novelty of the proposal developed in this work is the development of a model to ensure the continued quality of service perceived by end users via vertical handover (or handoff), which characterizes itself as a need for a global solution, i.e., the model is generic and technology independent, allowing its adoption in any network environment taking advantage of the capillary already available from legacy networks. It is also analyzed the situation in which an end user is simultaneously accessing services managed by different Service Providers, which leads to two possible situations: a) the user is accessing different services contracted to different Service Providers; b) the user is accessing the same service contracted to different Service Providers. In this last situation may be necessary to trigger a handover process requiring the decision of which the Providers shall execute it in accordance with the SPHDA - Service Providers Handover Decision Agreement. The methodology adopted for the model development was the RM-ODP - Reference Model for Open Distributed Processing, as it includes all technical and commercial aspects necessary for its construction.

Coreografias de serviços Web representam uma forma mais escalável e flexível de compor serviços do que uma abordagem centralizada como a orquestração, e seu papel na integração e comunicação de sistemas de larga escala é vital para os objetivos da SOC (Computação Orientada a Serviços) e da Internet do Futuro. Atualmente coreografias de serviços Web possuem vários desafios de pesquisa, dos quais a qualidade de serviço (QoS) e o monitoramento de coreografias de serviçosWeb são linhas importantes. O objetivo deste trabalho é propor e implementar um mecanismo de monitoramento não intrusivo de coreografias de serviços Web baseado em SLAs (Acordos de Nível de Serviço) que especificam as restrições de atributos de QoS de maneira probabilística. Esta dissertação propõe um mecanismo para coreografias de serviços Web que: (1) define requisitos de QoS; (2) especifica contratos probabilísticos sobre parâmetros de QoS usando SLA; e (3) realiza um monitoramento não intrusivo de coreografias de serviços Web para detectar violações de SLA. / Web services choreographies are a more scalable and flexible way to compose services than a centralized approach like orchestrations, and its role in the integration and communication of large-scale systems is vital for the goals of SoC (Service Oriented Computing) and Future Internet. Currently,Web services choreographies have several research challenges. From all challenges, quality of service (QoS) and monitoring of Web services choreography are important research lines. The goal of this work is to propose and implement a mechanism for non-intrusive monitoring of Web services choreography based on SLAs (Service Level Agreements) that define constraints of QoS attributes in a probabilistic way. This thesis proposes a mechanism for Web services choreographies that:(1) defines QoS requirements; (2) specifies probabilistic contracts on QoS parameters using SLAs; and (3) monitors, non-intrusively, the enactment of Web services choreographies to detect SLA violations.