3 research outputs found
Video Quality Prediction for Video over Wireless Access Networks (UMTS and WLAN)
Transmission of video content over wireless access networks (in particular, Wireless Local
Area Networks (WLAN) and Third Generation Universal Mobile Telecommunication System (3G UMTS)) is growing exponentially and gaining popularity, and is predicted to expose new revenue streams for mobile network operators. However, the success of these video applications over wireless access networks very much depend on meeting the user’s Quality of Service (QoS) requirements. Thus, it is highly desirable to be able to predict and, if appropriate, to control video quality to meet user’s QoS requirements. Video quality is
affected by distortions caused by the encoder and the wireless access network. The impact of these distortions is content dependent, but this feature has not been widely used in existing
video quality prediction models.
The main aim of the project is the development of novel and efficient models for video
quality prediction in a non-intrusive way for low bitrate and resolution videos and to
demonstrate their application in QoS-driven adaptation schemes for mobile video streaming
applications. This led to five main contributions of the thesis as follows:(1) A thorough understanding of the relationships between video quality, wireless access network (UMTS and WLAN) parameters (e.g. packet/block loss, mean burst length
and link bandwidth), encoder parameters (e.g. sender bitrate, frame rate) and content type is provided. An understanding of the relationships and interactions between them
and their impact on video quality is important as it provides a basis for the development of non-intrusive video quality prediction models.(2) A new content classification method was proposed based on statistical tools as content
type was found to be the most important parameter.
(3) Efficient regression-based and artificial neural network-based learning models were
developed for video quality prediction over WLAN and UMTS access networks. The
models are light weight (can be implemented in real time monitoring), provide a measure for user perceived quality, without time consuming subjective tests. The models have potential applications in several other areas, including QoS control and
optimization in network planning and content provisioning for network/service
providers.(4) The applications of the proposed regression-based models were investigated in (i)
optimization of content provisioning and network resource utilization and (ii) A new
fuzzy sender bitrate adaptation scheme was presented at the sender side over WLAN and UMTS access networks.
(5) Finally, Internet-based subjective tests that captured distortions caused by the encoder
and the wireless access network for different types of contents were designed. The
database of subjective results has been made available to research community as there is a lack of subjective video quality assessment databases.Partially sponsored by EU FP7 ADAMANTIUM Project (EU Contract 214751
Conception des réseaux maillés sans fil à multiples-radios multiples-canaux
Généralement, les problèmes de conception de réseaux consistent à sélectionner les arcs et
les sommets d’un graphe G de sorte que la fonction coût est optimisée et l’ensemble de
contraintes impliquant les liens et les sommets dans G sont respectées. Une modification dans le critère d’optimisation et/ou dans l’ensemble de contraintes mène à une nouvelle représentation d’un problème différent. Dans cette thèse, nous nous intéressons au problème de conception d’infrastructure de réseaux maillés sans fil (WMN- Wireless Mesh Network en Anglais) où nous montrons que la conception de tels réseaux se transforme d’un
problème d’optimisation standard (la fonction coût est optimisée) à un problème
d’optimisation à plusieurs objectifs, pour tenir en compte de nombreux aspects, souvent
contradictoires, mais néanmoins incontournables dans la réalité. Cette thèse, composée de
trois volets, propose de nouveaux modèles et algorithmes pour la conception de WMNs où
rien n’est connu à l’ avance.
Le premiervolet est consacré à l’optimisation simultanée de deux objectifs
équitablement importants : le coût et la performance du réseau en termes de débit. Trois
modèles bi-objectifs qui se différent principalement par l’approche utilisée pour maximiser
la performance du réseau sont proposés, résolus et comparés.
Le deuxième volet traite le problème de placement de passerelles vu son impact sur la
performance et l’extensibilité du réseau. La notion de contraintes de sauts (hop constraints)
est introduite dans la conception du réseau pour limiter le délai de transmission. Un nouvel
algorithme basé sur une approche de groupage est proposé afin de trouver les positions
stratégiques des passerelles qui favorisent l’extensibilité du réseau et augmentent sa
performance sans augmenter considérablement le coût total de son installation.
Le dernier volet adresse le problème de fiabilité du réseau dans la présence de pannes
simples. Prévoir l’installation des composants redondants lors de la phase de conception
peut garantir des communications fiables, mais au détriment du coût et de la performance
du réseau. Un nouvel algorithme, basé sur l’approche théorique de décomposition en
oreilles afin d’installer le minimum nombre de routeurs additionnels pour tolérer les pannes
simples, est développé.
Afin de résoudre les modèles proposés pour des réseaux de taille réelle, un algorithme
évolutionnaire (méta-heuristique), inspiré de la nature, est développé. Finalement, les
méthodes et modèles proposés on été évalués par des simulations empiriques et
d’événements discrets.Generally, network design problems consist of selecting links and vertices of a graph G so
that a cost function is optimized and all constraints involving links and the vertices in G are
met. A change in the criterion of optimization and/or the set of constraints leads to a new
representation of a different problem. In this thesis, we consider the problem of designing
infrastructure Wireless Mesh Networks (WMNs) where we show that the design of such
networks becomes an optimization problem with multiple objectives instead of a standard
optimization problem (a cost function is optimized) to take into account many aspects, often
contradictory, but nevertheless essential in the reality.
This thesis, composed of three parts, introduces new models and algorithms for
designing WMNs from scratch.
The first part is devoted to the simultaneous optimization of two equally important
objectives: cost and network performance in terms of throughput. Three bi-objective models
which differ mainly by the approach used to maximize network performance are proposed,
solved and compared.
The second part deals with the problem of gateways placement, given its impact on
network performance and scalability. The concept of hop constraints is introduced into the
network design to reduce the transmission delay. A novel algorithm based on a clustering
approach is also proposed to find the strategic positions of gateways that support network
scalability and increase its performance without significantly increasing the cost of installation.
The final section addresses the problem of reliability in the presence of single failures.
Allowing the installation of redundant components in the design phase can ensure reliable
communications, but at the expense of cost and network performance. A new algorithm is
developed based on the theoretical approach of "ear decomposition" to install the minimum
number of additional routers to tolerate single failures.
In order to solve the proposed models for real-size networks, an evolutionary algorithm
(meta-heuristics), inspired from nature, is developed. Finally, the proposed models and
methods have been evaluated through empirical and discrete events based simulations
> REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER (DOUBLE-CLICK HERE TO EDIT) < Intelligent Content Aware Services in 3G Wireless Networks
Abstract—In this paper, we address the problem of optimizing the delivery of multimedia services with different quality of service (QoS) requirements to mobile users. We assume that the network provides two distinct classes of service (CoS) to which users may subscribe: Premium, or Economy. Subscribers to the Premium service pay more for their connections but receive a higher level of quality measured by a set of parameters such as call blocking probability, coding rate, and format of the multimedia services. By optimizing the delivery of the multimedia services, we mean that the network guarantees that all users receive their agreed-upon contractual level of quality while maximizing the links ’ throughput, avoiding congestion, and maintaining the QoS requirements for each type of media (e.g., video, voice and data). Our proposed solution is based upon utilizing Genetic Algorithms (GAs) to solve a multi-objectiv