Content-Aware Multimedia Communications

The demands for fast, economic and reliable dissemination of multimedia information are steadily growing within our society. While people and economy increasingly rely on communication technologies, engineers still struggle with their growing complexity. Complexity in multimedia communication originates from several sources. The most prominent is the unreliability of packet networks like the Internet. Recent advances in scheduling and error control mechanisms for streaming protocols have shown that the quality and robustness of multimedia delivery can be improved significantly when protocols are aware of the content they deliver. However, the proposed mechanisms require close cooperation between transport systems and application layers which increases the overall system complexity. Current approaches also require expensive metrics and focus on special encoding formats only. A general and efficient model is missing so far. This thesis presents efficient and format-independent solutions to support cross-layer coordination in system architectures. In particular, the first contribution of this work is a generic dependency model that enables transport layers to access content-specific properties of media streams, such as dependencies between data units and their importance. The second contribution is the design of a programming model for streaming communication and its implementation as a middleware architecture. The programming model hides the complexity of protocol stacks behind simple programming abstractions, but exposes cross-layer control and monitoring options to application programmers. For example, our interfaces allow programmers to choose appropriate failure semantics at design time while they can refine error protection and visibility of low-level errors at run-time. Based on some examples we show how our middleware simplifies the integration of stream-based communication into large-scale application architectures. An important result of this work is that despite cross-layer cooperation, neither application nor transport protocol designers experience an increase in complexity. Application programmers can even reuse existing streaming protocols which effectively increases system robustness.Der Bedarf unsere Gesellschaft nach kostengünstiger und zuverlässiger Kommunikation wächst stetig. Während wir uns selbst immer mehr von modernen Kommunikationstechnologien abhängig machen, müssen die Ingenieure dieser Technologien sowohl den Bedarf nach schneller Einführung neuer Produkte befriedigen als auch die wachsende Komplexität der Systeme beherrschen. Gerade die Übertragung multimedialer Inhalte wie Video und Audiodaten ist nicht trivial. Einer der prominentesten Gründe dafür ist die Unzuverlässigkeit heutiger Netzwerke, wie z.B.~dem Internet. Paketverluste und schwankende Laufzeiten können die Darstellungsqualität massiv beeinträchtigen. Wie jüngste Entwicklungen im Bereich der Streaming-Protokolle zeigen, sind jedoch Qualität und Robustheit der Übertragung effizient kontrollierbar, wenn Streamingprotokolle Informationen über den Inhalt der transportierten Daten ausnutzen. Existierende Ansätze, die den Inhalt von Multimediadatenströmen beschreiben, sind allerdings meist auf einzelne Kompressionsverfahren spezialisiert und verwenden berechnungsintensive Metriken. Das reduziert ihren praktischen Nutzen deutlich. Außerdem erfordert der Informationsaustausch eine enge Kooperation zwischen Applikationen und Transportschichten. Da allerdings die Schnittstellen aktueller Systemarchitekturen nicht darauf vorbereitet sind, müssen entweder die Schnittstellen erweitert oder alternative Architekturkonzepte geschaffen werden. Die Gefahr beider Varianten ist jedoch, dass sich die Komplexität eines Systems dadurch weiter erhöhen kann. Das zentrale Ziel dieser Dissertation ist es deshalb, schichtenübergreifende Koordination bei gleichzeitiger Reduzierung der Komplexität zu erreichen. Hier leistet die Arbeit zwei Beträge zum aktuellen Stand der Forschung. Erstens definiert sie ein universelles Modell zur Beschreibung von Inhaltsattributen, wie Wichtigkeiten und Abhängigkeitsbeziehungen innerhalb eines Datenstroms. Transportschichten können dieses Wissen zur effizienten Fehlerkontrolle verwenden. Zweitens beschreibt die Arbeit das Noja Programmiermodell für multimediale Middleware. Noja definiert Abstraktionen zur Übertragung und Kontrolle multimedialer Ströme, die die Koordination von Streamingprotokollen mit Applikationen ermöglichen. Zum Beispiel können Programmierer geeignete Fehlersemantiken und Kommunikationstopologien auswählen und den konkreten Fehlerschutz dann zur Laufzeit verfeinern und kontrolliere

Final report on the evaluation of RRM/CRRM algorithms

Deliverable public del projecte EVERESTThis deliverable provides a definition and a complete evaluation of the RRM/CRRM algorithms selected in D11 and D15, and evolved and refined on an iterative process. The evaluation will be carried out by means of simulations using the simulators provided at D07, and D14.Preprin

QoS provisioning and mobility management for IP-based wireless LAN

Today two major technological forces drive the telecommunication era: the wireless cellular systems and the Internet. As these forces converge, the demand for new services, increasing bandwidth and ubiquitous connectivity continuously grows. The next-generation mobile systems will be based solely or in a large extent, on the Internet Protocol (IP). This thesis begins by addressing the problems and challenges faced in a multimedia, IP-based Wireless LAN environment. The ETSI HiperLAN/2 system has been mainly selected as the test wireless network for our theoretical and simulation experiments. Apart from the simulations, measurements have been taken from real life test scenarios, where the IEEE 802.11 system was used (UniS Test-bed). Furthermore, a brief overview of the All-IP network infrastructure is presented. An extension to the conventional wireless (cellular) architecture, which takes advantage of the IP network characteristics, is considered. Some of the trends driving the 3G and WLANs developments are explored, while the provision of quality of service on the latter for real-time and non-real-time multimedia services is investigated, simulated and evaluated. Finally, an efficient and catholic Q0S framework is proposed. At the same time, the multimedia services should be offered in a seamless and uninterrupted manner to users who access the all-IP infrastructure via a WLAN, meeting the demands of both enterprise and public environments anywhere and anytime. Thus providing support for mobile communications not only in terms of terminal mobility, as is currently the case, but also for session, service and personal mobility. Furthermore, this mobility should be available over heterogeneous networks, such as WLANs, IJMTS, as well as fixed networks. Therefore, this work investigates issues such as, multilayer and multi-protocol (SIP-Mobile IP-Cellular IP) mobility management in wireless LAN and 3G domains. Several local and global mobility protocols and architectures have been tested and evaluated and a complete mobility management framework is proposed. Moreover, integration of simple yet efficient authentication, accounting and authorisation mechanisms with the multimedia service architecture is an important issue of IP-based WLANs. Without such integration providers will not have the necessary means to control their provided services and make revenue from the users. The proposed AAA architecture should support a robust AAA infrastructure providing secure, fast and seamless access granting to multimedia services. On the other hand, a user wishing a service from the All-IP WLAN infrastructure needs to be authenticated twice, once to get access to the network and the other one should be granted for the required service. Hence, we provide insights into these issues by simulating and evaluating pre-authentication techniques and other network authentication scenarios based on the wellknown IEEE 802.lx protocol for multimedia IP-based WLANs.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Quality-oriented adaptation scheme for multimedia streaming in local broadband multi-service IP networks

The research reported in this thesis proposes, designs and tests the Quality-Oriented Adaptation Scheme (QOAS), an application-level adaptive scheme that offers high quality multimedia services to home residences and business premises via local broadband IP-networks in the presence of other traffic of different types. QOAS uses a novel client-located grading scheme that maps some network-related parameters’ values, variations and variation patterns (e.g. delay, jitter, loss rate) to application-level scores that describe the quality of delivery. This grading scheme also involves an objective metric that estimates the end-user perceived quality, increasing its effectiveness. A server-located arbiter takes content and rate adaptation decisions based on these quality scores, which is the only information sent via feedback by the clients. QOAS has been modelled, implemented and tested through simulations and an instantiation of it has been realized in a prototype system. The performance was assessed in terms of estimated end-user perceived quality, network utilisation, loss rate and number of customers served by a fixed infrastructure. The influence of variations in the parameters used by QOAS and of the networkrelated characteristics was studied. The scheme’s adaptive reaction was tested with background traffic of different type, size and variation patterns and in the presence of concurrent multimedia streaming processes subject to user-interactions. The results show that the performance of QOAS was very close to that of an ideal adaptive scheme. In comparison with other adaptive schemes QOAS allows for a significant increase in the number of simultaneous users while maintaining a good end-user perceived quality. These results are verified by a set of subjective tests that have been performed on viewers using a prototype system

Adaptive delay-constrained internet media transport

Reliable transport layer Internet protocols do not satisfy the requirements of packetized, real-time multimedia streams. The available thesis motivates and defines predictable reliability as a novel, capacity-approaching transport paradigm, supporting an application-specific level of reliability under a strict delay constraint. This paradigm is being implemented into a new protocol design -- the Predictably Reliable Real-time Transport protocol (PRRT). In order to predictably achieve the desired level of reliability, proactive and reactive error control must be optimized under the application\u27s delay constraint. Hence, predictably reliable error control relies on stochastic modeling of the protocol response to the modeled packet loss behavior of the network path. The result of the joined modeling is periodically evaluated by a reliability control policy that validates the protocol configuration under the application constraints and under consideration of the available network bandwidth. The adaptation of the protocol parameters is formulated into a combinatorial optimization problem that is solved by a fast search algorithm incorporating explicit knowledge about the search space. Experimental evaluation of PRRT in real Internet scenarios demonstrates that predictably reliable transport meets the strict QoS constraints of high-quality, audio-visual streaming applications.Zuverlässige Internet-Protokolle auf Transport-Layer erfüllen nicht die Anforderungen paketierter Echtzeit-Multimediaströme. Die vorliegende Arbeit motiviert und definiert Predictable Reliability als ein neuartiges, kapazitäterreichendes Transport-Paradigma, das einen anwendungsspezifischen Grad an Zuverlässigkeit unter strikter Zeitbegrenzung unterstützt. Dieses Paradigma wird in ein neues Protokoll-Design implementiert -- das Predictably Reliable Real-time Transport Protokoll (PRRT). Um prädizierbar einen gewünschten Grad an Zuverlässigkeit zu erreichen, müssen proaktive und reaktive Maßnahmen zum Fehlerschutz unter der Zeitbegrenzung der Anwendung optimiert werden. Daher beruht Fehlerschutz mit Predictable Reliability auf der stochastischen Modellierung des Protokoll-Verhaltens unter modelliertem Paketverlust-Verhalten des Netzwerkpfades. Das Ergebnis der kombinierten Modellierung wird periodisch durch eine Reliability Control Strategie ausgewertet, die die Konfiguration des Protokolls unter den Begrenzungen der Anwendung und unter Berücksichtigung der verfügbaren Netzwerkbandbreite validiert. Die Adaption der Protokoll-Parameter wird durch ein kombinatorisches Optimierungsproblem formuliert, welches von einem schnellen Suchalgorithmus gelöst wird, der explizites Wissen über den Suchraum einbezieht. Experimentelle Auswertung von PRRT in realen Internet-Szenarien demonstriert, dass Transport mit Predictable Reliability die strikten Auflagen hochqualitativer, audiovisueller Streaming-Anwendungen erfüllt

Optimização de recursos para difusão em redes de próxima geração

Doutoramento em ElectrotecniaEsta tese aborda o problema de optimização de recursos de rede, na entrega de Serviços de Comunicação em Grupo, em Redes de Próxima Geração que suportem tecnologias de difusão. De acordo com esta problemática, são feitas propostas que levam em atenção a evolução espectável das redes 3G em Redes Heterogéneas de Próxima Geração que incluam tecnologias de difusão tais como o DVB. A optimização de recursos em Comunicações em Grupo é apresentada como um desafio vertical que deve cruzar diversas camadas. As optimizações aqui propostas cobrem tanto a interface entre Aplicação e a Plataforma de Serviços para a disponibilização de serviços de comunicação em grupo, como as abstracções e mapeamentos feitos na interface entre a Rede Central e a Rede de Acesso Rádio. As optimizações propostas nesta tese, assumem que o caminho evolutivo na direcção de uma Rede de Próxima Geração é feito através do IP. Em primeiro lugar são endereçadas as optimizações entre a Aplicação e a Plataforma de Serviços que já podem ser integradas nas redes 3G existentes. Estas optimizações podem potenciar o desenvolvimento de novas e inovadoras aplicações, que através do uso de mecanismos de distribuição em difusão podem fazer um uso mais eficiente dos recursos de rede. De seguida são apresentadas optimizações ao nível da interface entre a Rede Central e a Rede de Acesso Rádio que abordam a heterogeneidade das redes futuras assim como a necessidade de suportar tecnologias de difusão. É ainda considerada a possibilidade de aumentar a qualidade de serviço de serviços de difusão através do mapeamento do IP multicast em portadoras unidireccionais. Por forma a validar todas estas optimizações, vários protótipos foram desenvolvidos com base num router avançado para redes de acesso de próxima geração. As funcionalidades e arquitectura de software desse router são também aqui apresentadas.This thesis addresses the problem of optimizing network resource usage, for the delivery of Group Services, in Next Generation Networks featuring broadcast technologies. In this scope, proposals are made according to the expected evolution of 3G networks into Next Generation Heterogeneous Networks that include broadcast technologies such as DVB. Group Communication resource optimization is considered a vertical challenge that must cross several layers. The optimizations here proposed cover both Application to Service Platform interfaces for group communication services, and Core Network to Radio Access Network interface abstractions and mappings. The proposed optimizations are also presented taking into consideration network evolution path towards an All-IP based Next Generation Network. First it is addressed the Application to Service Platform optimization, which can already be deployed over 3G networks. This optimization could potentiate the development of new and innovative applications that through the use of broadcast/multicast service delivery mechanisms could be more efficient network wise. Next proposals are made on the Core Network to Radio Access Network interfaces that address the heterogeneity of future networks and consider the need to support broadcast networks. It is also considered the possibility to increase the Quality of Service of broadcast/multicast services based on the dynamic mapping of IP multicast into unicast radio bearers. In order to validate these optimizations, several prototypes were built based on an advanced access router for next generation networks. Such access router functionalities and software architecture are also presented here

Journal of Telecommunications and Information Technology, 2004, nr 2

kwartalni

Toward a versatile transport protocol

Les travaux présentés dans cette thèse ont pour but d'améliorer la couche transport de l'architecture réseau de l'OSI. La couche transport est de nos jour dominée par l'utilisation de TCP et son contrôle de congestion. Récemment de nouveaux mécanismes de contrôle de congestion ont été proposés. Parmi eux TCP Friendly Rate Control (TFRC) semble être le plus abouti. Cependant, tout comme TCP, ce mécanisme ne prend pas en compte ni les évolutions du réseau ni les nouveaux besoins des applications. La première contribution de cette thèse consiste en une spécialisation de TFRC afin d'obtenir un protocole de transport avisé de la Qualité de Service (QdS) spécialement défini pour des réseaux à QdS offrant une garantie de bande passante. Ce protocole combine un mécanisme de contrôle de congestion orienté QdS qui prend en compte la réservation de bande passante au niveau réseau, avec un service de fiabilité totale afin de proposer un service similaire à TCP. Le résultat de cette composition constitue le premier protocole de transport adapté à des réseau à garantie de bande passante. En même temps que cette expansion de service au niveau réseau, de nouvelles technologies ont été proposées et déployées au niveau physique. Ces nouvelles technologies sont caractérisées par leur affranchissement de support filaire et la mobilité des systèmes terminaux. De plus, elles sont généralement déployées sur des entités où la puissance de calcul et la disponibilité mémoire sont inférieures à celles des ordinateurs personnels. La deuxième contribution de cette thèse est la proposition d'une adaptation de TFRC à ces entités via la proposition d'une version allégée du récepteur. Cette version a été implémentée, évaluée quantitativement et ses nombreux avantages et contributions ont été démontrés par rapport à TFRC. Enfin, nous proposons une optimisation des implémentations actuelles de TFRC. Cette optimisation propose tout d'abord un nouvel algorithme pour l'initialisation du récepteur basé sur l'utilisation de l'algorithme de Newton. Nous proposons aussi l'introduction d'un outil nous permettant d'étudier plus en détails la manière dont est calculé le taux de perte du côté récepteur. ABSTRACT : This thesis presents three main contributions that aim to improve the transport layer of the current networking architecture. The transport layer is nowadays overruled by the use of TCP and its congestion control. Recently new congestion control mechanisms have been proposed. Among them, TCP Friendly Rate Control (TFRC) appears to be one of the most complete. Nevertheless this congestion control mechanism, as TCP, does not take into account either the evolution of the network in terms of Quality of Service and mobility or the evolution of the applications. The first contribution of this thesis is a specialisation TFRC congestion control to propose a QoS-aware Transport Protocol specifically designed to operate over QoS-enabled networks with bandwidth guarantee mechanisms. This protocol combines a QoS-aware congestion control, which takes into account networklevel bandwidth reservations, with full reliability in order mechanism to provide a transport service similar to TCP. As a result, we obtain the guaranteed throughput at the application level where TCP fails. This protocol is the first transport protocol compliant with bandwidth guaranteed networks. At the same time the set of network services expands, new technologies have been proposed and deployed at the physical layer. These new technologies are mainly characterised by communications done without wire constraint and the mobility of the end-systems. Furthermore, these technologies are usually deployed on entities where the CPU power and memory storage are limited. The second contribution of this thesis is therefore to propose an adaptation of TFRC to these entities. This is accomplished with the proposition of a new sender-based version of TFRC. This version has been implemented, evaluated and its numerous contributions and advantages compare to usual TFRC version have been demonstrated. Finally, we proposed an optimisation of actual implementations of TFRC. This optimisation first consists in the proposition of an algorithm based on a numerical analysis of the equation used in TFRC and the use of the Newton's algorithm. We furthermore give a first step, with the introduction of a new framework for TFRC, in order to better understand TFRC behaviour and to optimise the computation of the packet loss rate according to loss probability distribution