A Context Quality Model to Support Transparent Reasoning with Uncertain Context

Much research on context quality in context-aware systems divides into two strands: (1) the qualitative identication of quality measures and (2) the use of uncertain reasoning techniques. In this paper, we combine these two strands, exploring the problem of how to identify and propagate quality through the dierent context layers in order to support the context reasoning process. We present a generalised, struc- tured context quality model that supports aggregation of quality from sensor up to situation level. Our model supports reasoning processes that explicitly aggregate context quality, by enabling the identication and quantication of appropriate quality parameters. We demonstrate the ecacy of our model using an experimental sensor data set, gaining a signicant improvement in situation recognition for our voting based reasoning algorithm

A Context Quality Model to Support Transparent Reasoning with Uncertain Context

Much research on context quality in context-aware systems divides into two strands: (1) the qualitative identification of quality measures and (2) the use of uncertain reasoning techniques. In this paper, we combine these two strands, exploring the problem of how to identify and propagate quality through the different context; layers in order to support the context reasoning process. We present a generalised, structured context quality model that supports aggregation of quality from sensor up to situation level. Our model supports reasoning processes that explicitly aggregate context quality, by enabling the identification and quantification of appropriate quality parameters. We demonstrate the efficacy of our model using an experimental sensor data set, gaining a significant improvement in situation recognition for our voting based reasoning algorithm.</p

Recognition Situations Using Extended Dempster-Shafer Theory

Weiser’s [111] vision of pervasive computing describes a world where technology seamlessly integrates into the environment, automatically responding to peoples’ needs. Underpinning this vision is the ability of systems to automatically track the situation of a person. The task of situation recognition is critical and complex: noisy and unreliable sensor data, dynamic situations, unpredictable human behaviour and changes in the environment all contribute to the complexity. No single recognition technique is suitable in all environments. Factors such as availability of training data, ability to deal with uncertain information and transparency to the user will determine which technique to use in any particular environment. In this thesis, we propose the use of Dempster-Shafer theory as a theoretically sound basis for situation recognition - an approach that can reason with uncertainty, but which does not rely on training data. We use existing operations from Dempster-Shafer theory and create new operations to establish an evidence decision network. The network is used to generate and assess situation beliefs based on processed sensor data for an environment. We also define two specific extensions to Dempster-Shafer theory to enhance the knowledge that can be used for reasoning: 1) temporal knowledge about situation time patterns 2) quality of evidence sources (sensors) into the reasoning process. To validate the feasibility of our approach, this thesis creates evidence decision networks for two real-world data sets: a smart home data set and an officebased data set. We analyse situation recognition accuracy for each of the data sets, using the evidence decision networks with temporal/quality extensions. We also compare the evidence decision networks against two learning techniques: Naïve Bayes and J48 Decision Tree

Gestion de la qualité de contexte pour l'intelligence ambiante

L'informatique sensible au contexte vise à réduire la quantité d'informations explicites qu'un utilisateur doit fournir pour que le système accomplisse la tâche souhaitée. Ceci est particulièrement vrai dans le domaine récent de l'intelligence ambiante où les objets de la vie courante deviennent capables de déclencher une action ou un échange spontané d'informations, sans interaction avec l'utilisateur. Les progrès techniques en matière de réseaux de communication sans fil, d'équipements mobiles individuels, de capteurs et de logiciels embarqués, rendent aujourd'hui possibles des services aux usagers dépendants du contexte, mais les applications concrètes demeurent encore très limitées. Les travaux existants dans la littérature décomposent la gestion de contexte en quatre fonctionnalités: la collecte, l'interprétation, la détection de situations et l'utilisation pour l'adaptation. L'élément discriminant des solutions existantes est la qualité des informations abstraites obtenues par inférence et devant caractériser les situations de l'utilisateur. Les limites de ces solutions sont le manque de composition aisée des informations de contexte, le passage à l'échelle, tant en termes de quantité d'informations de contexte que de nombre d'applications clientes, l'absence de garantie sur la cohérence et la qualité des informations de contexte, et le manque de solutions intergicielles permettant de libérer le concepteur d'applications des aspects liés à la gestion de contexte. Nous nous intéressons dans cette thèse à la gestion de la qualité de contexte (QoC) dans un environnement ambiant. Les problématiques de gestion de la qualité de contexte sont multiples: choisir la méthode adéquate pour la gestion du contexte, extraire la qualité associée au contexte, interpréter et analyser la qualité de contexte pour les applications sensibles au contexte. Nous proposons de répondre à ces problématiques en intégrant la qualité de contexte au sein de la plateforme de gestion de contexte COSMOS (http://picoforge.lntevrv.fr/proiects/svn/cosmos) de l'équipe MARGE (http://www-inf.itsudparis.eu/MARGE) de Télécom SudParis. Afin d'effectuer cette intégration, nous avons conçu des éléments spécifiques à la qualité de contexte et avons mis en place une gestion fine et efficiente de cette qualité en limitant le surcoût associé. Nous proposons également un processus de conception basé sur l'ingénierie dirigée par les modèles afin de générer les éléments requis à la gestion de la qualité de contexte. Nous avons validé nos contributions à l'aide de deux applications fonctionnant sur téléphone mobile : une application de "vente flash" dans un centre commercial et une application de détection de localisation sur un campus. Les tests de performances que nous avons effectués permettent de comparer les résultats avec et sans la prise en compte de la QoC et montrent le faible coût de la gestion de la qualité par rapport aux améliorations apportées aux applications sensibles au contexteContext-aware computing aims to reduce the amount of explicit information required from a user for a system to perform a task. This is particularly true in the recent domain of ambient intelligence where everyday life objects are able to trigger an action or a spontaneous information exchange, without any interaction with the user. Technical advances in wireless communication, personal mobile devices, sensors and embedded software make context-aware services possible, but concrete applications are still very limited. The solutions proposed in the literature decompose context management into four functions: acquisition, interpretation, situation detection and application adaptation. The differentiating element in these proposals is the quality of the high-level context information obtained by inference and characterising the situation of the user. The limits of these solutions are the difficulty for composing context information scalability in terms of the quantity of context information and of the number of client applications, the absence of guarantee on the consistency of context information and the lack of middleware solutions able to free the designer of context-aware applications from the management of context data. In this thesis, we are interested in the management of the quality of context information (QoC) in an ambient environment. There are several key issues in QoC management: choosing the adequate method for context management, extracting the quality associated to the context, analysing and interpreting the quality of the context with regard to the requirements of context-aware applications. We propose to answer these questions by integrating QoC management into the COSMOS context management framework (http://picoforge.int-evry.fr/projects/svn/cosmos) developed by the MARGE team (http://www-inf.itsudparis.eu/MARGE) of Télécom SudParis.For this purpose, we have designed the necessary components dedicated to QoC management and we have implemented the mechanisms allowing a fine-grain manipulation of the QoC together with a limitation of the associated overhead. We also propose a design process based on model-driven engineering in order to automatically generate the elements responsible of QoC management. We validate our contributions through the development of two prototype applications running on mobile phones: a Flash sale offer application to be used in malls and a location detection application proposed to the students of a campus. The performance tests we have conducted allow to compare the results obtained with and without taking into account the QoC and show the low overhead associated to QoC manaqement with regard to the benefits brought to context-aware applications and servicesEVRY-INT (912282302) / SudocSudocFranceF

Courtier en qualité de contexte pour les applications mobiles

Résumé Plusieurs travaux de recherche ont mis en évidence la nécessité de la prise en charge de la qualité des informations de contexte pour les applications mobiles sensibles aux contextes. Différentes architectures permettant la gestion de la qualité du contexte (QdC) ont étudié proposées. Bien que ces solutions identifient les métriques de QdC les plus pertinentes, proposent des méthodes de quantification pour ces métriques, ou encore expliquent comment exploiter les données sur la QdC, peu abordent l'interface entre les sources d'information de contexte et leurs destinataires. En eet, lorsque deux sources sont disponibles pour la mème information de contexte, il est utile de disposer d'un mécanisme permettant de déterminer la source offrant la QdC adéquate. Dans ce mémoire, nous proposons une modélisation de la qualité de contexte ainsi que la spécification et l'implémentation d'une architecture offrant un mécanisme de sélection d'un fournisseur de contexte garantissant le respect des besoins en qualité de contexte des consommateurs. Nos principaux objectifs sont la minimisation de la charge des fournisseurs et consommateurs et la minimisation de la signalisation. Notre solution se caractérise par la mise en place d'un système de courtage entre les fournisseurs d'information de contexte et leurs consommateurs. Le courtier, entité centrale, prend en charge la gestion de la qualité de contexte. Le consommateur se réfère au courtier afin de se voir attribuer un fournisseur répondant à ses besoins. Il peut alors envoyer ses requêtes de contexte. Notre modèle de qualité de contexte suppose une formulation simple de celle-ci par les consommateurs et fournisseurs. Au final, la spécification de notre architecture suppose le respect de nos deux premiers objectifs. De plus, les tests menés sur notre implémentation du courtier en qualité de contexte confirme que nous les avons atteint. An de mesurer notre contribution à la recherche nous avons comparé nos travaux à ceux d'autres chercheurs et constaté une amélioration des possibilitées de mise à l'échelle offert par notre architecture.----------Abstract Research has already highlighted the need to support quality of context information in context-aware mobile applications. Various architectures enabling the management of quality of context (QoC) has been proposed. Although these solutions identify the most relevant metrics of QoC, oer methods of quantication for these metrics, or explain how to use data on QoC, only a few consider the interface between the sources of context and their recipients. Actually, when two sources are available for the same context information, it becomes useful to have a mechanism to determine the source oering suitable QoC. In this thesis, we propose a model of quality of context, the specication and implementation of an architecture providing a mechanism for selecting a context provider which ensure that the quality of context oered by the provider complies the consumer needs. Our main objectives are the minimization of the providers and consumers workload, and the minimization of the overhead. Our solution is to set up a brokerage system between context information providers and their consumers. The broker, central element, supports the management of the quality of context. The consumer refers to the broker to be assigned a provider that meets its needs. It can then send context queries. Our model of quality of context oer a simple formulation, which is benecial to the reduction of consumers and suppliers workload. Finally, the specication of our architecture predicate the respect of our rst two objectives. Moreover, experiments conducted on our implementation of the quality of context broker conrms that we have achieved our objectives. To measure our contribution to the research we have compared our work with other research and found that our architecture oer better opportunities for scaling

La contextualisation en entreprise (mettre en avant utilisateurs et développeurs)

Les applications contextuelles doivent gérer un flux contenu de contexte selon une logique approprié. Les travaux de recherche en contextualisation se limitent à proposer des plateformes de développement proposant des mécanismes d adaptation prédéfinie. Cette thèse se propose d étende l état de l art en proposant des nouveaux concepts formant la fondation pour la création d application contextuelles en adoptant des principes de l ingénierie logicielle et une décomposition fonctionnelle. Aussi, cela permet l intégration de comportements contextualisés à des applications non initialement conçus pour cela. La thèse propose une autre manière centrée-contexte permettant de séparer la représentation du contexte de son interprétation, offrant encore plus de flexibilité à la gestion de contexte. Les propositions sont analysées aux lumières d étude de cas et de simulations. Le résultat de la thèse est l introduction de nouvelle approche de création d applications contextuelles qui met en avant le développeur mais aussi l utilisateurContext-aware applications must manage a continuous stream of context according to dedicated business logic. Research was limited on proposing frameworks and platforms that have predefined behavior toward applications. This thesis attempts to extend background works by proposing new concepts serving as foundation for a flexible approach for building context-aware applications. The thesis examines the state of the art of context-aware computing, then adopts well-established software design principles and a functional decomposition for designing a reference model for context management enabling seamless integration of context-awareness into applications. Also, the thesis studies the use of context in common applications and proposes a context-centric modeling approach which allows the creation of a graph-based representation where entities are connected to each other through links representing context. Furthermore, the context graph decouples the presentation and the semantics of context, leaving each application to manage the appropriate semantic for their context data. Case studies are conducted for the evaluation of the proposed system in terms of its support for the creation of applications enhanced with context-awareness. A simulation study is performed to analyze the performance properties of the proposed system. The result of this thesis is the introduction of a novel approach for supporting the creation of context-aware applications that supports the integration of context-awareness to existing applications. It empowers developers as well as users to participate in the creation process, thereby reducing usability issuesEVRY-INT (912282302) / SudocSudocFranceF

Methods of implementation of context-aware platforms and context-aware user interfaces for applications in consumer electronics

U okviru disertacije predstavljene su metode realizacije kontekstualnih platformi i kontekstualnih korisničkih sprega za uređaje potrošačke elektronike. Predloženi su algoritmi semantizacije konteksta i procene zauzetosti korisnika, arhitektura rešenja i rezultati evaluacije.  In this dissertation methods of implementation of context-aware platforms and context-aware user interfaces for applications in consumer electronics are presented. The work includes the proposition of algorithms for context semantization and user availability estimation, architecture of the solution as well as the results of evaluation experiments