Haptic-based Virtual Reality (VR) applications have many merits. What is still obscure, from the designer’s perspective of these applications, is the experience the users will undergo when they use the VR system. Quality of Experience (QoE) is an evaluation metric from the user’s perspective that unfortunately has received limited attention from the research community. Assessing the QoE of VR applications reflects the amount of overall satisfaction and benefits gained from the application in addition to laying the foundation for ideal user-centric design in the future. In this thesis, we address certain issues and concerns regarding QoE of virtual environments. In essence, we propose a taxonomy for the evaluation of the QoE for multimedia applications and in particular VR applications. The taxonomy classifies QoE related parameters into groups. The groups’ organization is generated from the definition we have adopted for the QoE which is the Quality of Service (QoS) plus the user experience (UX). We model this taxonomy using first mathematical modeling based on weighted averages and then a Fuzzy logic Inference System (FIS) to quantitatively measure the QoE of haptic virtual environments. We test both models conducting user study analysis to evaluate the QoE of a VR application. These models serve as engines that facilitate the calculation of QoE with minimal amount of users. We specifically attend to the issue of the new media, haptics, within the context of increasing the QoE of virtual environments (VE). This special attention is important for comparing the effect of tactile and kinesthetic feedback on the QoE. In accordance, we investigate a particular topic that seems to have a colossal effect on QoE throughout our analysis, which is fatigue. Our analysis involved users' studies since the main focus is on the user. The QoE for virtual environments is in its primary stages. This thesis tackles issues that are vital in dealing with and understanding the importance of QoE. The various results suggest a positive user's disposition toward haptics and virtual environments, yet there will always be obstacles and challenges such as fatigue that if minimized will enhance the QoE of haptic-based applications.

Les technologies de relief tridimensionnel (3D) ont récemment reçu un nouvel attrait. Lesraisons potentielles sont que ces technologies peuvent fournir une expérience visuelle plusriche et plus immersive. En effet, un observateur peut extraire les disparités binoculairesprésentées entre les vues gauche et droite, pour retrouver plus efficacement la profondeur dela scène visuelle observée, et ainsi, trouver une nouvelle dimension dans le contenu.Cependant, tandis que la valeur de la profondeur est plutôt bien appréciée, un certain nombrede problèmes qui impactent la qualité de l’expérience dans les représentations 3D ont étéidentifiés. L’objective de cette thèse est d’étudier les principaux facteurs qui affectent laqualité de l’expérience en stéréoscopie dans le but de fournir des méthodes qui pourraientaméliorer l’utilisation des systèmes stéréoscopiques. Trois aspects majeurs de la qualité del’expérience sont adressés : (1) les sources et causes de la fatigue visuelle, (2) les distorsionsperceptives et (3) l’amélioration de la qualité de l’expérience en 3D au travers de l’adaptationdu contenu visuel. Pour étudier la fatigue visuelle, les mouvements de vergence étaientmesurés à la fois avec un écran 3D et avec un système à double écran qui permettaient laprésentation de stimuli avec les informations de disparité et de flou présentés en congruencecomme en incongruence. L’effet de la stéréoscopie sur les mouvements de vergence a étéétudié dans le but de tester si la mesure oculaire pouvait être utilisée comme indicateur defatigue visuelle. Le sujet suivant étudiait la consistance de la perception des formes 3Dstéréoscopiques en fonction de distances virtuelles induites par la disparité et par le signald’accommodation. Le rôle de la taille de la pupille et de la profondeur de champ enstéréoscopie étaient étudiés par la manipulation de la taille de la pupille avec deux conditionsd’illumination contrôlée. Finalement, l’amélioration de la perception de la forme 3D estquestionnée au travers de l’adaptation du contenu visuel en fonction de la mesure de seuilsperceptifs individuels pour des stimuli se déplaçant en profondeur. / Stereoscopic 3-Dimensional (S3D) technology has recently received growing attraction,potentially because it provides a more informative and more immersive visual experience.Indeed, the viewer may extract the binocular disparities displayed between the left and theright views, more efficiently retrieve the depth of the observed visual scene, and thus, givevisual content another dimension. However, while the additional value of depth is ratherappreciated, a number of problems have been raised that impact the Quality of Experience(QoE) in S3D representations. The objective of this thesis is to investigate the main factorsaffecting QoE in stereopsis in order to provide guidelines towards the improvement andfurther use of stereoscopic systems. Three main aspects of QoE in S3D are addressed: (1) thesources and causes of visual fatigue, (2) the perceptual distortions arising in S3D and, (3) theimprovement of S3D QoE through content adaptation. To study visual fatigue in S3D,vergence eye movements were measured both in S3D display and in dual-screen display thatenables the presentation of matched disparity and defocus stimuli. The effect of stereopsis onvergence movements was studied so as to test whether vergence tracking can be used asindicator of visual fatigue. The next topic investigated the consistency in stereoscopic 3Dshape perception as a function of vergence distance and accommodation distance. The role ofthe pupil size and the depth of focus in S3D were evaluated by manipulating the pupilaperture with two controlled lighting conditions. Finally, the improvement of 3D shapeperception is addressed through content adaptation according to individual perceptionthresholds measurement for motion-in-depth stimuli.

VR gaming is an emerging market with relatively new technology when compared to PC and console gaming. Streamed VR gaming is when the VR game is being streamed from another device to the VR headset. This experiment will show how the VR hardware and software performs under network constraints such as RTT and packet loss for streamed VR gaming specifically. User QoE (quality of experience) will be gathered and compiled into MOS (mean opinion score) for later use in graphs to determine negative trends. All collected data will also be sent to the Infovista technical team so they can make theoretical models on how user QoE is affected by network conditions. This thesis will show how the QoS (quality of service) factors, such as latency and packet loss, impact the users overall QoE and the VR headsets FPS. Before the subjective experiment could begin a testbed was chosen and setup, a VR game was decided on, and a streaming service was tested on. During the experiment the game Serious Sam VR: The Last Hope was played and NVIDIA’s CloudXR streaming service was used. The testbed setup consisted of two PCs, one router, one access point, a tablet used for user reviews, and a VR headset with two handheld controllers. The software program ALTRUIST was used for managing the user data and applying the desired network conditions such as latency. Each user experiment tested 28 different network conditions with varying values of RTT (round trip time), Packet loss, RTT with packet loss, and RTT with random jitter. 30 users were gathered for the actual experiment where the Calendly application was used to manage the user appointments. The results consisted of objective and subjective data gathered during the experiments. From the objective data it could be determined that RTT primarily affects the FPS in the VR headset. Packet loss affected the FPS but to a minor degree compared to RTT. RTT of 175 ms received an average FPS of 53 while 24% packet loss yielded approximately 65 FPS. Random jitter had close to no impact on the FPS according to the results. The subjective data suggests that RTT of 75 ms and below yields a good user MOS and RTT of 175 ms gives an acceptable user MOS at 3 out of 5. Packet loss of 6% and below gives a good user MOS while 12% and above results in poor MOS. RTT with random jitter performs average to poorly with Standard deviation of 3 and above, for low RTT values. For future experiments it is advisableto use ALTRUIST or a similar software to help the researcher during the experiment.

Mobile cloud gaming (MCG) is an emerging concept which aims to deliver video games on-demand to users with the use of cloud technologies. Cloud technology allows the offloading of computation from a less powerful user device or thin client to more robust cloud servers to minimize power consumption and provide additional cloud services such as storage. MCG is therefore very helpful that can reduce the costs of expensive hardware, but the challenge is that it requires a high Quality of Service (QoS) in order to stream and play the games where the users have a high Quality of Experience (QoE). The goal of the study is to investigate how users' QoE is affected by network conditions while playing MCG and compare the results from a previous study. A testbed was made in order to conduct subjective tests where users are going to play Counter Strike: Global Offensive (CS: GO) on a smartphone using Steam Remote Play. The testbed consists of a router, tablet, smartphone, headset, Xbox controller, USB-C multi-port adapter and four different PC's. Participants on campus, both students and non-students, were invited to participate in the experiment. A total of 24 participants completed the tests; however, results from two participants were excluded due to software issues. There were 23 network conditions that was tested for each user and included factors such as round-trip time (RTT), packet losses, bursty jitter, random jitter or combinations of different factors. A multi-platform tool, ALTRUIST, was used to control the applications and facilitate the data collection from the devices and NetEm changed the network conditions. The results showed that the network condition [bj(rtt200i15)] had the highest mean opinion score (MOS) of the QoE of 4.5 for the users with 200 milliseconds of bursty jitter every 15 seconds. The worst network condition tested with the lowest QoE rating of 1.4 was network condition [rtt25pl12] that had 25 milliseconds of RTT and 12% packet losses. There were differences between the male and female participants where the MOS of the QoE results was significantly higher with up to 1.5 MOS QoE rating differences for the females compared to the males in network conditions with RTT with packet losses. However, the sample size was low with only 5 female participants compared to 18 male participants. The MOS of the QoE results separating play time under 10 hours per week and 10 or more hours per week showed no significant changes, where the largest QoE rating difference was 0.5 points. Network condition [rtt25pl12] and [rtt2pl35] had the largest differences in the MOS QoE ratings compared to the previous study, while both was not compared to the same corresponding network condition. The largest difference comparing the same network condition to the previous study was network condition [bj(rtt200i15)] with a difference of 1.1 points higher in the MOS QoE rating.

The Information and Communication Technology (ICT) industry is one of the most energy consuming industries in the world. With the increase of the number of global mobile traffic users which is growing rapidly for each year, it is more important than ever for all industries to implement energy efficient methods to decrease the greenhouse gas emissions. This thesis looks into Ericsson, one of the largest companies within ICT, and how their energy efficient methods in LTE impact the end-users. The experiment was conducted in an Ericsson laboratory in Lund and the results showed that some quality of service metrics (latency,throughput, etc.) were impacted by the different energy efficient features enabled. However, performing a mean opinion score showed that the end-users were not as affected while browsing through different sites and streaming videos in 720p. While the experiment was performed on a smaller scale (4 User Equipments and 3 end-users) the result was promising enough for it to be conducted on a larger scale in the future. With enough data Ericsson and other ICT companies can be able to convince mobile operators to enable more energy efficient features (without it having any impact on the end-users) while fighting the climate change.

There has been an increased demand on the mobile infrastructure, with enhancement in technology, content delivery and regulatory changes on access and competition rules. According to Ericsson the mobile data traffic is expected to grow with 45% from 2013 until 2019. These changes have to do with the fact that the service provider’s traditional pricing schemes are distinguishing. These changes enables new business models. The main two drivers behind the growth of mobile data traffic are (1) increased number of mobile data subscribers and (2) the average volume per subscriber has increased. At the same time the revenues are growing extremely slow in comparison with data usage, the revenues from the mobile broadband are limited to just a few cents off ARPU. One of the operator looking at different solutions in order to reduce the revenue gap is Telenor. Telenor wants to incorporate in its business model is videoconference with QoE taken into account. They have therefore developed a new service called Appear.in. Appear.in is challenging the existing video conferencing market. The main goal of the thesis is to investigate how business model for videoconference services changes when quality of experience is taken into account. Furthermore what will the effect be of having QoE in the BM? The primary steps that needs to be considered in order to achieve the goal is to identify the ecosystem of videoconference solutions and analyzing the business models that can be considered to deploy videoconference systems. Several workshops and survey was conducted. Moreover two different Business Model Canvas was created with and without QoE. A comparison was made and based on these comparisons one can conclude that there is not must that differs. When QoE is considered, three out of nine building blocks in the Business Model Canvas gets affected by the addition of QoE, value proposition, customer relationship and customer segment. These building blocks gets involved with customers in one way or the other. By including QoE in the Business Model Canvas showed a way to keep the customers satisfied. Furthermore companies would have the advantage of monitoring and tracking every movement allowing for quick decisions, guaranteeing video quality by preventing the development of videos problems. A number of investigations have been done in the area of Videoconferencing from a technology point of view, but one can find very little research related to Business model. General studies in the field of business model over QoE are being carried out. This thesis is a first step towards a wider and deeper investigation in the area of Videoconferencing with QoE from a Business model point of view. / Nya paradigm i både grossist- och detaljhandel håller på att bildas och accelereras av tekniska framsteg, content delivery, och regeländringar om tillgång och konkurrensregler. Dessutom så har efterfrågan på den mobila infrastrukturen ökat drastiskt. Enligt Ericsson förväntas mobildatatrafiken öka sin årliga tillväxttakt på cirka 45 % mellan 2013 och 2019. Det finns en ökad användning av det mobila bredbandet datatrafik samt antalet abonnenter. Samtidigt växer intäkterna extremt långsam i jämförelse med dataanvändning, intäkterna från mobilt bredband är begränsade till bara några cent av ARPU. Telenor överväger att i sin affärsmodell även lägga till videokonferens med QoE i åtanke. Telenor Digital har utvecklat en ny tjänst Appear.in. Genom att använda en ny standard för realtidskommunikation är Appear.in med och utmanar den befintliga videokonferensmarknaden. Huvudsyftet med avhandlingen är att undersöka hur affärsmodellen för videokonferens tjänster förändras när man tar hänsyn till QoE. Vidare vad kommer effekterna att bli med QoE i affärsmodellen? De primära steg som måste övervägas för att uppnå målet är att identifiera ekosystemet videokonferenslösningar och analysera affärsmodeller som kan anses implementera videokonferenssystem. Ett flertal workshops, kartläggningar och enkätundersökningar genomfördes. Två olika Business Model Canvas skapades en med och en utan QoE. En jämförelse gjordes och baserat på dessa jämförelser kan man dra slutsatsen att det inte finns någon stor skillnad mellan dessa båda modeller. När man tar hänsyn till QoE, så påverkas tre av de nio byggstenarna i Business Model Canvas, värde proposition, kundrelationer och kundsegment. Dessa byggstenar blir involverad med kunder på ett eller annat sätt.Genom att inkludera QoE i sin Business Model Canvas kan man hålla sina kunder nöjda. Dessutom kan företagen ha fördelen att övervaka och spåra varje rörelse, vilket möjliggör snabba beslut, vilket garanterar bildkvalitet genom att förhindra utvecklingen av video problem. En hel del forskning har gjorts på området videokonferens från en teknik synvinkel, men man hittar mycket lite forskning relaterad till affärsmodell. Allmänna studier inom affärsmodeller över QoE har genomförs. Denna avhandling är ett första steg mot en bredare och djupare forskning inom området videokonferens med QoE från en affärsmodell synvinkel.

The last advancements in technology leads to an easy acquisition and spreading of multi-dimensional multimedia content, e.g. videos, which in many cases depict human faces. From such videos, valuable information describing the intrinsic characteristic of the recorded user can be retrieved: the features extracted from the facial patch are relevant descriptors that allow for the measurement of subject's emotional status or the identification of synthetic characters. One of the emerging challenges is the development of contactless approaches based on face analysis aiming at measuring the emotional status of the subject without placing sensors that limit or bias his experience. This raises even more interest in the context of Quality of Experience (QoE) measurement, or the measurement of user emotional status when subjected to a multimedia content, since it allows for retrieving the overall acceptability of the content as perceived by the end user. Measuring the impact of a given content to the user can have many implications from both the content producer and the end-user perspectives. For this reason, we pursue the QoE assessment of a user watching multimedia stimuli, i.e. 3D-movies, through the analysis of his facial features acquired by means of contactless approaches. More specifically, the user's Heart Rate (HR) was retrieved by using computer vision techniques applied to the facial recording of the subject and then analysed in order to compute the level of engagement. We show that the proposed framework is effective for long video sequences, being robust to facial movements and illumination changes. We validate it on a dataset of 64 sequences where users observe 3D movies selected to induce variations in users' emotional status. From one hand understanding the interaction between the user's perception of the content and his cognitive-emotional aspects leads to many opportunities to content producers, which may influence people's emotional statuses according to needs that can be driven by political, social, or business interests. On the other hand, the end-user must be aware of the authenticity of the content being watched: advancements in computer renderings allowed for the spreading of fake subjects in videos. Because of this, as a second challenge we target the identification of CG characters in videos by applying two different approaches. We firstly exploit the idea that fake characters do not present any pulse rate signal, while humans' pulse rate is expressed by a sinusoidal signal. The application of computer vision techniques on a facial video allows for the contactless estimation of the subject's HR, thus leading to the identification of signals that lack of a strong sinusoidality, which represent virtual humans. The proposed pipeline allows for a fully automated discrimination, validated on a dataset consisting of 104 videos. Secondly, we make use of facial spatio-temporal texture dynamics that reveal the artefacts introduced by computer renderings techniques when creating a manipulation, e.g. face swapping, on videos depicting human faces. To do so, we consider multiple temporal video segments on which we estimated multi-dimensional (spatial and temporal) texture features. A binary decision of the joint analysis of such features is applied to strengthen the classification accuracy. This is achieved through the use of Local Derivative Patterns on Three Orthogonal Planes (LDP-TOP). Experimental analyses on state-of-the-art datasets of manipulated videos show the discriminative power of such descriptors in separating real and manipulated sequences and identifying the creation method used. The main finding of this thesis is the relevance of facial features in describing intrinsic characteristics of humans. These can be used to retrieve significant information like the physiological response to multimedia stimuli or the authenticity of the human being itself. The application of the proposed approaches also on benchmark dataset returned good results, thus demonstrating real advancements in this research field. In addition to that, these methods can be extended to different practical application, from the autonomous driving safety checks to the identification of spoofing attacks, from the medical check-ups when doing sports to the users' engagement measurement when watching advertising. Because of this, we encourage further investigations in such direction, in order to improve the robustness of the methods, thus allowing for the application to increasingly challenging scenarios.

The rapid evolution of portable devices and social media has enabled pervasive forms of distributed cooperation. A group could perform a task using a heterogeneous set of the devices (desktop, mobile), connections (wireless, wired, 3G) and software clients. We call this form of systems Distributed Dynamic Cooperative Environments (DDCEs). Content in DDCEs is created and shared by the users. The content could be static (e.g., video or audio), dynamic (e.g.,wikis), and/or Objects with behavior. Objects with behavior are programmed objects that take advantage of the available computational services (e.g., cloud-based services). Providing a desired Quality of Experience (QoE) in DDCEs is a challenge for cooperative systems designers. DDCEs are expected to provide groups with the utmost flexibility in conducting their cooperative activities. More flexibility at the user side means less control and predictability of the groups' behavior at the system side. Due to the lack of Quality of Service (QoS) guarantees in DDCEs, groups may experience changes in the system behavior that are usually manifested as delays and inconsistencies in the shared state. We question the extent to which cooperation among group members is sensitive to system changes in DDCEs. We argue that a QoE definition for groups should account for cooperation emergence and sustainability. An experiment was conducted, where fifteen groups performed a loosely-coupled task that simulates social traps in a 3D virtual world. The groups were exposed to two forms of system delays. Exo-content delays are exogenous to the provided content (e.g., network delay). Endo-content delays are endogenous to the provided content (e.g., delay in processing time for Objects with behavior). Groups' performance in the experiment and their verbal communication have been recorded and analyzed. The results demonstrate the nonlinearity of groups' behavior when dealing with endo-content delays. System interventions are needed to maintain QoE even though that may increase the cost or the required resources. Systems are designed to be used rather than understood by users. When the system behavior changes, designers have two choices. The first is to expect the users to understand the system behavior and adjust their interaction accordingly. That did not happen in our experiment. Understanding the system behavior informed groups' behavior. It partially influenced how the groups succeeded or failed in accomplishing its goal. The second choice is to understand the semantics of the application and provide guarantees based on these semantics. Based on our results, we introduce the following design guidelines for QoE provision in DDCEs. • If possible the system should keep track of information about group goals and add guarding constraints to protect these goals. • QoE guarantees should be provided based on the semantics of the user-generated content that constitutes the group activity. • Users should be given the option to define the content that is sensitive to system changes (e.g., Objects with behavior that are sensitive to delays or require intensive computations) to avoid the negative impacts of endo-content delays. • Users should define the Objects with behavior that contribute to the shared state in order for the system to maintain the consistency of the shared state. • Endo-content delays were proven to have significantly negative impacts on the groups in our experiment compared to exo-content delays. We argue that system designers, if they have the choice, should trade processing time needed for Objects with behavior for exo-content delay. / Ph. D.

<p>Recent advancements in deep learning (DL) and high-communication bandwidth access networks such as 5G enable applications that require intelligence and faster computational power at the edge with low power consumption. In this thesis, we study how to improve the Quality-of-Experience (QoE) of these emerging 5G applications, e.g., virtual reality (VR) and video analytics on edge devices. These 5G applications either require high-quality visual effects with a stringent latency requirement (for VR) or high analytics accuracy (for video analytics) while maintaining frame rate requirements under dynamic conditions. </p> <p>In part 1, we study how to support high-quality untethered immersive multiplayer VR on commodity mobile devices. Simply replicating the prior-art for a single-user VR will result in a linear increase in network bandwidth requirement that exceeds the bandwidth of WiFi (802.11ac). We propose a novel technique, <em>Coterie, </em>that splits the rendering of background environment (BE) frames between the mobile device and the edge server that drastically enhances the similarity of the BE frames and reduces the network load via frame caching and reuse. Our proposed VR framework, Coterie, reduces per-player network requirement by over 10x and easily supports 4 players on Pixel 2 over 802.11ac while maintaining the QoE constraints of 4K VR.</p> <p>In part 2, we study how to achieve high accuracy of analytics in video analytics pipelines (VAP). We observe that the frames captured by the surveillance video cameras powering a variety of 24X7 analytics applications are not always pristine -- they can be distorted due to environmental condition changes, lighting issues, sensor noise, compression, etc. Such distortions not only deteriorate the accuracy of deep learning applications but also negatively impact the utilization of the edge server resources used to run these computationally expensive DL models. First, we study how to dynamically filter out low-quality frames captured. We propose a lightweight DL-based quality estimator, <em>AQuA</em>, that can be used to filter out low-quality frames that can lead to high-confidence errors (false-positives) if fed into the analytic units (AU) in the VAP. AQuA-filter reduces false positives by 17% and the compute and network usage by up to 27% when used in a face-recognition VAP. Second, we study how to reduce such poor-quality frame captures by the camera. We propose <em>CamTuner, </em>a system that automatically and dynamically adapts the complex camera settings to changing environmental conditions based on analytical quality estimation to enhance the accuracy of video analytics. In a real customer deployment, <em>CamTuner</em> enhances VAP accuracy by detecting 15.9% additional persons and 2.6%–4.2% additional cars (without any false positives) than the default camera setting. While <em>CamTuner</em> focuses on improving the accuracy of single-AU running on a camera stream, next we present <em>Elixir</em>, a system that enhances the video stream quality for multiple analytics on a video stream by jointly optimizing different AUs’ objectives. In a real-world deployment, <em>Elixir</em> correctly detects 7.1% (22,068) and 5.0% (15,731) more cars, 94% (551) and 72% (478) more faces, and 670.4% (4975) and 158.6% (3507) more persons than the default-camera-setting and time-sharing approaches, respectively.</p>

Les récentes avancées technologiques permettent désormais la fabrication de terminaux mobiles de plus en plus compacts et dotés de plusieurs interfaces réseaux. Le nouveau modèle de consommation de médias se résume par le concept "Anytime, Anywhere, Any Device" et impose donc de nouvelles exigences en termes de déploiement de services ubiquitaires. Cependant la conception et le developpement de réseaux ubiquitaires et convergents de nouvelles générations soulèvent un certain nombre de défis techniques. Les standards actuels ainsi que les solutions commerciales pourraient être affectés par le manque de considération du contexte utilisateur. Le ressenti de l'utilisateur concernant certains services multimédia tels que la VoIP et l'IPTV dépend fortement des capacités du terminal et des conditions du réseau d'accès. Cela incite les réseaux de nouvelles générations à fournir des services ubiquitaires adaptés à l'environnement de l'utilisateur optimisant par la même occasion ses resources. L'IP Multimedia Subsystem (IMS) est une architecture de nouvelle génération qui centralise l'accès aux services et permet la convergence des réseaux fixe/mobile. Néanmoins, l'évolution de l'IMS est nécessaire sur les points suivants :- l'introduction de la sensibilité au contexte utilisateur et de la PQoS (Perceived QoS) : L'architecture IMS ne prend pas en compte l'environnement de l'utilisateur, ses préférences et ne dispose pas d'un méchanisme de gestion de PQOS. Pour s'assurer de la qualité fournit à l'utilisateur final, des informations sur l'environnement de l'utilisateur ainsi que ses préférences doivent transiter en cœur de réseau afin d'y être analysés. Ce traitement aboutit au lancement du service qui sera adapté et optimisé aux conditions observées. De plus pour le service d'IPTV, les caractéristiques spatio-temporelles de la vidéo influent de manière importante sur la PQoS observée côté utilisateur. L'adaptation des services multimédias en fonction de l'évolution du contexte utilisateur et de la nature de la vidéo diffusée assure une qualité d'expérience à l'utilisateur et optimise par la même occasion l'utilisation des ressources en cœur de réseau.- une solution de mobilité efficace pour les services conversationnels tels que la VoIP : Les dernières publications 3GPP fournissent deux solutions de mobilité: le LTE propose MIP comme solution de mobilité alors que l'IMS définit une mobilité basée sur le protocole applicatif SIP. Ces standards définissent le système de signalisation mais ne s'avancent pas sur la gestion du flux média lors du changement d'interface réseau. La deuxième section introduit une étude comparative détaillée des solutions de mobilité dans les NGNs.Notre première contribution est la spécification de l'architecture globale de notre plateforme IMS sensible au contexte utilisateur réalisée au sein du projet Européen ADAMANTIUM. Nous détaillons tout d'abord le serveur MCMS intelligent placé dans la couche application de l'IMS. Cet élément récolte les informations de qualité de services à différents équipements réseaux et prend la décision d'une action sur l'un de ces équipements. Ensuite nous définissons un profil utilisateur permettant de décrire son environnement et de le diffuser en coeur de réseau. Une étude sur la prédiction de satisfaction utilisateur en fonction des paramètres spatio-temporels de la vidéo a été réalisée afin de connaître le débit idéal pour une PQoS désirée.Notre deuxième contribution est l'introduction d'une solution de mobilité adaptée aux services conversationnels (VoIP) tenant compte du contexte utilisateur. Notre solution s'intègre à l'architecture IMS existante de façon transparente et permet de réduire le temps de latence du handover. Notre solution duplique les paquets de VoIP sur les deux interfaces actives pendant le temps de la transition. Parallèlement, un nouvel algorithme de gestion de mémoire tampon améliore la qualité d'expérience pour le service de VoIP. / The latest advances in technology have already defied Moore’s law. Thanks to research and industry, hand-held devices are composed of high processing embedded systems enabling the consumption of high quality services. Furthermore, recent trends in communication drive users to consume media Anytime, Anywhere on Any Device via multiple wired and wireless network interfaces. This creates new demands for ubiquitous and high quality service provision management. However, defining and developing the next generation of ubiquitous and converged networks raise a number of challenges. Currently, telecommunication standards do not consider context-awareness aspects for network management and service provisioning. The experience felt by the end-user consuming for instance Voice over IP (VoIP) or Internet Protocol TeleVision (IPTV) services varies depending mainly on user preferences, device context and network resources. It is commonly held that Next Generation Network (NGN) should deliver personalized and effective ubiquitous services to the end user’s Mobile Node (MN) while optimizing the network resources at the network operator side. IP Multimedia Subsystem (IMS) is a standardized NGN framework that unifies service access and allows fixed/mobile network convergence. Nevertheless IMS technology still suffers from a number of confining factors that are addressed in this thesis; amongst them are two main issues :The lack of context-awareness and Perceived-QoS (PQoS):-The existing IMS infrastructure does not take into account the environment of the user ,his preferences , and does not provide any PQoS aware management mechanism within its service provisioning control system. In order to ensure that the service satisfies the consumer, this information need to be sent to the core network for analysis. In order to maximize the end-user satisfaction while optimizing network resources, the combination of a user-centric network management and adaptive services according to the user’s environment and network conditions are considered. Moreover, video content dynamics are also considered as they significantly impact on the deduced perceptual quality of IPTV services. -The lack of efficient mobility mechanism for conversational services like VoIP :The latest releases of Third Generation Partnership Project (3GPP) provide two types of mobility solutions. Long-Term Evolution (LTE) uses Mobile IP (MIP) and IMS uses Session Initiation Protocol (SIP) mobility. These standards are focusing on signaling but none of them define how the media should be scheduled in multi-homed devices. The second section introduces a detailed study of existing mobility solutions in NGNs. Our first contribution is the specification of the global context-aware IMS architecture proposed within the European project ADAptative Management of mediA distributioN based on saTisfaction orIented User Modeling (ADAMANTIUM). We introduce the innovative Multimedia Content Management System (MCMS) located in the application layer of IMS. This server combines the collected monitoring information from different network equipments with the data of the user profile and takes adaptation actions if necessary. Then, we introduce the User Profile (UP) management within the User Equipment (UE) describing the end-user’s context and facilitating the diffusion of the end-user environment towards the IMS core network. In order to optimize the network usage, a PQoS prediction mechanism gives the optimal video bit-rate according to the video content dynamics. Our second contribution in this thesis is an efficient mobility solution for VoIP service within IMS using and taking advantage of user context. Our solution uses packet duplication on both active interfaces during handover process. In order to leverage this mechanism, a new jitter buffer algorithm is proposed at MN side to improve the user’s quality of experience. Furthermore, our mobility solution integrates easily to the existing IMS platform.