An unprecedented era of “connected vehicles” is becoming an imminent reality. This is driven by advances in vehicular communications, and the development of in-vehicle telematics systems supporting a plethora of applications. The diversity and multitude of such developments will, however, introduce excessive congestion across wireless infrastructure, compelling operators to expand their networks. An alternative to network expansions is to develop more efficient content delivery paradigms. In particular, alleviating Radio Access Network (RAN) congestion is important to operators as it postpones costly investments in radio equipment installations and new spectrum. Efficient RAN frameworks are therefore paramount to expediting this realm of vehicular connectivity. Fortunately, the predictability of human mobility patterns, particularly that of vehicles traversing road networks, offers unique opportunities to pursue proactive RAN transmission schemes. Knowing the routes vehicles are going to traverse enables the network to forecast spatio-temporal demands and predict service outages that specific users may face. This can be accomplished by coupling the mobility trajectories with network coverage maps to provide estimates of the future rates users will encounter along a trip. In this thesis, we investigate how this valuable contextual information can enable RANs to improve both service quality and operational efficiency. We develop a collection of methods that leverage mobility predictions to jointly optimize 1) long-term wireless resource allocation, 2) adaptive video streaming delivery, and 3) energy efficiency in RANs. Extensive simulation results indicate that our approaches provide significant user experience gains in addition to large energy savings. We emphasize the applicability of such predictive RAN mechanisms to video streaming delivery, as it is the predominant source of traffic in mobile networks, with projections of further growth. Although we focus on exploiting mobility information at the radio access level, our framework is a direction towards pursuing a predictive end-to-end content delivery architecture. / Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2014-04-30 06:15:34.31

Over the last decade, the wide deployment of wireless access technologies (e.g. WiFi, 3G, and LTE) and the remarkable growth in the volume of streaming video content have significantly altered the telecommunications field. These developments introduce new challenges to the research community including the need to develop new solutions (e.g. traffic models and transport protocols) to address changing traffic patterns and the characteristics of wireless links and the need for new evaluation methods that generate higher fidelity results under more realistic scenarios. Unfortunately, for the last two decades, simulation studies have been the main tool for researchers in wireless networks. In spite of the advantages of simulation studies, overall they have had a negative influence on the credibility of published results. In partial response to this simulation crisis, the research community has adopted testing and evaluation using implementation-based experiments. Implementation-based experiments include field experiments, prototypes, emulations, and testbeds. An example of an implementation-based experiment is the MANIAC Challenge, a wireless networking competition that we designed and hosted, which included creation and operation of ad hoc networks using commodity hardware. However, the lack of software tools to facilitate these sorts of experiments has created new challenges. Currently, researchers must practice kernel programming in order to implement networking experiments, and there is an urgent need to lower the barriers of entry to wireless network experimentation. With respect to the growth in video traffic over wireless networks, the main challenge is a mismatch between the design concepts of current internet protocols (e.g. the Transport Control Protocol (TCP)) and the reality of modern wireless networks and streaming video techniques. Internet protocols were designed to be deployed over wired networks and often perform poorly over wireless links; video encoding is highly loss tolerant and delay-constrained and yet, for reasons of expedience is carried using protocols that emphasize reliable delivery at the cost of potentially high delay. This dissertation addresses the lack of software tools to support implementation-based networking experiments and the need to improve the performance of video streaming over wireless access networks. We propose a new software tool that allows researchers to implement experiments without a need to become kernel programmers. The new tool, called the Flexible Internetwork Stack (FINS) Framework, is available under an open source license. With our tool, researchers can implement new network layers, protocols, and algorithms, and redesign the interconnections between the protocols. It offers logging and monitoring capabilities as well as dynamic reconfigurability of the modules' attributes and interconnections during runtime. We present details regarding the architecture, design, and implementation of the FINS Framework and provide an assessment of the framework including both qualitative and quantitative comparison with significant previous tools. We also address the problem of HTTP-based adaptive video streaming (HAVS) over WiFi access networks. We focus on the negative influence of wireless last-hop connections on network utilization and the end-user quality of experience (QoE). We use a cross-layer approach to design three controllers. The first and second controllers adopt a heuristic cross-layer design, while the third controller formulates the HAVS problem as a Markov decision process (MDP). By solving the model using reinforcement learning, we achieved 20% performance improvement (after enough training) with respect to the performance of the best heuristic controller under unstable channel conditions. Our simulation results are backed by a system prototype using the FINS Framework. Although it may seem predictable to achieve more gain in performance and in QoE by using cross-layer design, this dissertation not only presents a new technique that improves performance, but also suggests that it is time to move cross-layer and machine-learning-based approaches from the research field to actual deployment. It is time to move cognitive network techniques from the simulation environment to real world implementations. / Ph. D.

Network Utility Maximization (NUM) provides a key conceptual framework to study reward allocation amongst a collection of users/entities in disciplines as diverse as economics, law and engineering. However when the available resources and/or users' utilities vary over time, reward allocations will tend to vary, which in turn may have a detrimental impact on the users' overall satisfaction or quality of experience. In this thesis, we introduce a generalization of the NUM framework which incorporates the detrimental impact of temporal variability in a user's allocated rewards and explicitly incorporates Mean-Variability-Fairness tradeoffs, i.e., tradeoffs amongst the mean and variability in users' reward allocations, as well as fairness across users. We propose a simple online algorithm to realize these tradeoffs, which, under stationary ergodic assumptions, is shown to be asymptotically optimal, i.e., achieves a long term performance equal to that of an offline algorithm with knowledge of the future variability in the system. This substantially extends work on NUM to an interesting class of relevant problems where users/entities are sensitive to temporal variability in their service or allocated rewards. We extend the theoretical framework and tools developed for realizing Mean-Variability-Fairness tradeoffs to develop a simple online algorithm to solve the problem of optimizing video delivery in networks. The tremendous increase in mobile video traffic projected for the future along with insufficiency of available wireless network capacity makes this one of the most important networking problems today. Specifically, we consider a network supporting video clients streaming stored video, and focus on the problem of jointly optimizing network resource allocation and video clients' video quality adaptation. Our objective is to fairly maximize video clients' video Quality of Experience (QoE) realizing Mean-Variability-Fairness tradeoffs, incorporating client preferences on rebuffering time and the cost of video delivery. We present a simple asymptotically optimal online algorithm NOVA (Network Optimization for Video Adaptation) to solve the problem. Our algorithm uses minimal communication, 'distributes' the tasks of network resource allocation to a centralized network controller, and video clients' video quality adaptation to the respective video clients. Further, the quality adaptation is also optimal for standalone video clients, and is an asynchronous algorithm well suited for use in the Dynamic Adaptive Streaming over HTTP (DASH) framework. We also extend NOVA for use with more general video QoE models, and study NOVA accounting for practical considerations like time varying number of video clients, sharing with other types of traffic, performance under legacy resource allocation policies, videos with variable sized segments etc. / text

[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

Video streaming is widely recognized as the next Internet killer application. It was not one of the Internet's original target applications and its protocols (TCP in particular) were tuned mainly for e efficient bulk file transfer. As a result, a significant effort has focused on the development of UDP-based special protocols for streaming multimedia on the Internet. Recently, there has been a shift in video streaming from UDP to TCP, and specifically to HTTP. HTTP streaming provides a very attractive platform for video distribution on the Internet mainly because it can utilize all the current Internet infrastructure. In this thesis we make the argument that the marriage between HTTP streaming and the current Internet infrastructure can create many problems and inefficiencies. In order to solve these issues, we provide a set of techniques and protocols that can help both the network and end-hosts to make better decisions to improve video streaming quality. The thesis makes the following contributions: - We conduct a characterization study of popular commercial streaming services on mobile platforms. Our study shows that streaming services make different design decisions when implementing video players on different mobile platforms. We show that this can lead to several inefficiencies and undesirable behaviors specially when several clients compete for bandwidth in a shared bottleneck link. - Fairness between traffic flows has been preserved on the Internet through the use of TCP. However, due to the dynamics of adaptive video players and the lack of standard client adaptation techniques, fairness between multiple competing video flows is still an open issue of research. Our work extends the definition of standard bitrate fairness to utility fairness where utility is the Quality of Experience (QoE) of a video stream. We define QoE max-min fairness for a set of adaptive video flows competing for bandwidth in a network and we develop an algorithm that computes the set of bitrates that should be assigned to each stream to achieve fairness. We design and implement a system that can apply QoE fairness in home networks and evaluate the system on a real home router. - A well known problem that has been associated with TCP traffic is the buffer bloat problem. We use an experimental setup to show that adaptive video flows can cause buffer bloat which can significantly harm time sensitive applications sharing the same bottleneck link with video traffic. In addition, we develop a technique that can be used by video players to mitigate this problem. We implement our technique in a real video player and evaluate it on our testbed. - With the increasing popularity of video streaming on the Internet, the amounts of traffic on the peering links between video streaming providers and Internet Service Providers (ISPs) have become the source of many disputes. Hybrid CDN/P2P streaming systems can be used to reduce the amounts of traffic on the peering links by leveraging users upload bandwidth to redistribute some of the load to other peers. We develop an analysis for hybrid CDN/P2P systems that broadcast live adaptive video streams. The analysis helps the CDN to make better decisions to optimize video quality for its users.