Les travaux présentés s'inscrivent dans le cadre des systèmes mobiles et distribués, et s'intéressent tout particulièrement aux perspectives offertes par les réseaux locaux sans fil. A l'opposé de la complexité de déploiement d'une infrastructure cellulaire étendue, les interactions sans fil courte portée peuvent être utilisées de manière très simple, sans infrastructure. Ainsi, elles permettent à des calculateurs proches d'échanger automatiquement des informations. Nous proposons des supports système prenant en compte la volatilité des communications sans fil, et permettant de développer des applications tirant spontanément parti de la proximité physique des noeuds mobiles. Ces travaux sont ensuite étendus dans le cadre d'autres familles de réseaux sans fil. Ainsi, nous nous intéressons aux réseaux à couverture discontinue. La technologie support est la même que celle de notre première étude. Simplement, les communications entre les noeuds mobiles ne sont plus directes, mais passent par une borne fixe. Cette borne définit une bulle radio de taille limitée. C'est l'interconnexion de ces bulles, sans souci de continuité de la couverture radio, qui permet d'envisager un réseau étendu et simple à déployer. Dans ce cadre, les mécanismes système étudiés permettent de masquer l'intermittence de la connectivité, et autorisent le support d'applications exploitant les flux montants et descendants dans le réseau. Enfin, dans une dernière partie, nous abordons le problème du couplage système de deux architectures sans fil hétérogènes. Un tel couplage présente des objectifs comparables à ceux des réseaux à couverture discontinue : offrir des nouveaux services sur une couverture large, à des densités importantes d'utilisateurs mobiles. Ces travaux débouchent sur la définition de mécanismes permettant de coupler au sein d'un même service des propriétés fonctionnelles des deux infrastructures sans fil.

Intelligent devices are quickly becoming necessities to support our activities during both work and play. We are already bound in a symbiotic relationship with these devices. An unfortunate effect of the pervasiveness of intelligent devices is the substantial investment of our time and effort to communicate intent. Even though our increasing reliance on these intelligent devices is inevitable, the limits of conventional methods for devices to perceive human expression hinders communication efficiency. These constraints restrict the usefulness of intelligent devices to support our activities. Our communication time and effort must be minimized to leverage the benefits of intelligent devices and seamlessly integrate them into society. Minimizing the time and effort needed to communicate our intent will allow us to concentrate on tasks in which we excel, including creative thought and problem solving. <br /><br /> An intuitive method to minimize human communication effort with intelligent devices is to take advantage of our existing interpersonal communication experience. Recent advances in speech, hand gesture, and facial expression recognition provide alternate viable modes of communication that are more natural than conventional tactile interfaces. Use of natural human communication eliminates the need to adapt and invest time and effort using less intuitive techniques required for traditional keyboard and mouse based interfaces. <br /><br /> Although the state of the art in natural but isolated modes of communication achieves impressive results, significant hurdles must be conquered before communication with devices in our daily lives will feel natural and effortless. Research has shown that combining information between multiple noise-prone modalities improves accuracy. Leveraging this complementary and redundant content will improve communication robustness and relax current unimodal limitations. <br /><br /> This research presents and evaluates a novel multimodal framework to help reduce the total human effort and time required to communicate with intelligent devices. This reduction is realized by determining human intent using a knowledge-based architecture that combines and leverages conflicting information available across multiple natural communication modes and modalities. The effectiveness of this approach is demonstrated using dynamic hand gestures and simple facial expressions characterizing basic emotions. It is important to note that the framework is not restricted to these two forms of communication. The framework presented in this research provides the flexibility necessary to include additional or alternate modalities and channels of information in future research, including improving the robustness of speech understanding. <br /><br /> The primary contributions of this research include the leveraging of conflicts in a closed-loop multimodal framework, explicit use of uncertainty in knowledge representation and reasoning across multiple modalities, and a flexible approach for leveraging domain specific knowledge to help understand multimodal human expression. Experiments using a manually defined knowledge base demonstrate an improved average accuracy of individual concepts and an improved average accuracy of overall intents when leveraging conflicts as compared to an open-loop approach.

People relate with one another in space and through imagined and technologically mediated networks. This thesis is concerned with the relationship between these two types of social connections – spatial and network. Spatial connections structure collectives of people in the same place at the same time. Network connections structure relations between people without regard to place or time. Spatial connections are complex, but rigid by nature, while network connections are simple, but flexible. Essential articulations emerge between these two connection types. These articulations create and evolve contemporary socio-spatial systems such as the city, its many places, and groups of people therein. However, the basic human experience of these systems remains largely polarized between spatial and network social practices to the disadvantage of human agency. This thesis proposes a teleodynamic, socio-spatial interaction model for the articulation of these social practices in human agency architecture. The model is a mobile experience design that functions through people with ‘smart’ mobile devices. It connects them with one another in public place and to global information and communication networks simultaneously. Sociological study informs the model’s design – constraints and conditions for the connection extents and integrity of social interaction. The model supports self-organizing circular relationships between human interaction dynamics and their trace structures based on a methodology for emergence in complex systems. It effects the emergence of the aforementioned socio-spatial, human agency architecture, with great flexibility. The model and architecture together serve to better articulate contemporary spatial and network social practices to the benefit of human agency in urban space.

Intelligent devices are quickly becoming necessities to support our activities during both work and play. We are already bound in a symbiotic relationship with these devices. An unfortunate effect of the pervasiveness of intelligent devices is the substantial investment of our time and effort to communicate intent. Even though our increasing reliance on these intelligent devices is inevitable, the limits of conventional methods for devices to perceive human expression hinders communication efficiency. These constraints restrict the usefulness of intelligent devices to support our activities. Our communication time and effort must be minimized to leverage the benefits of intelligent devices and seamlessly integrate them into society. Minimizing the time and effort needed to communicate our intent will allow us to concentrate on tasks in which we excel, including creative thought and problem solving. <br /><br /> An intuitive method to minimize human communication effort with intelligent devices is to take advantage of our existing interpersonal communication experience. Recent advances in speech, hand gesture, and facial expression recognition provide alternate viable modes of communication that are more natural than conventional tactile interfaces. Use of natural human communication eliminates the need to adapt and invest time and effort using less intuitive techniques required for traditional keyboard and mouse based interfaces. <br /><br /> Although the state of the art in natural but isolated modes of communication achieves impressive results, significant hurdles must be conquered before communication with devices in our daily lives will feel natural and effortless. Research has shown that combining information between multiple noise-prone modalities improves accuracy. Leveraging this complementary and redundant content will improve communication robustness and relax current unimodal limitations. <br /><br /> This research presents and evaluates a novel multimodal framework to help reduce the total human effort and time required to communicate with intelligent devices. This reduction is realized by determining human intent using a knowledge-based architecture that combines and leverages conflicting information available across multiple natural communication modes and modalities. The effectiveness of this approach is demonstrated using dynamic hand gestures and simple facial expressions characterizing basic emotions. It is important to note that the framework is not restricted to these two forms of communication. The framework presented in this research provides the flexibility necessary to include additional or alternate modalities and channels of information in future research, including improving the robustness of speech understanding. <br /><br /> The primary contributions of this research include the leveraging of conflicts in a closed-loop multimodal framework, explicit use of uncertainty in knowledge representation and reasoning across multiple modalities, and a flexible approach for leveraging domain specific knowledge to help understand multimodal human expression. Experiments using a manually defined knowledge base demonstrate an improved average accuracy of individual concepts and an improved average accuracy of overall intents when leveraging conflicts as compared to an open-loop approach.

People relate with one another in space and through imagined and technologically mediated networks. This thesis is concerned with the relationship between these two types of social connections – spatial and network. Spatial connections structure collectives of people in the same place at the same time. Network connections structure relations between people without regard to place or time. Spatial connections are complex, but rigid by nature, while network connections are simple, but flexible. Essential articulations emerge between these two connection types. These articulations create and evolve contemporary socio-spatial systems such as the city, its many places, and groups of people therein. However, the basic human experience of these systems remains largely polarized between spatial and network social practices to the disadvantage of human agency. This thesis proposes a teleodynamic, socio-spatial interaction model for the articulation of these social practices in human agency architecture. The model is a mobile experience design that functions through people with ‘smart’ mobile devices. It connects them with one another in public place and to global information and communication networks simultaneously. Sociological study informs the model’s design – constraints and conditions for the connection extents and integrity of social interaction. The model supports self-organizing circular relationships between human interaction dynamics and their trace structures based on a methodology for emergence in complex systems. It effects the emergence of the aforementioned socio-spatial, human agency architecture, with great flexibility. The model and architecture together serve to better articulate contemporary spatial and network social practices to the benefit of human agency in urban space.

In this thesis computer-mediated human interaction and human computer interaction in responsive spaces are discussed. Can such spaces be de-signed to create an affective response from the players? What are the de-sign heuristics for a space that allows for the establishment of affective dy-namics? I research the user experience of players of existing spaces built by the Topological Media Lab. In addition to that I review other relevant ex-perimental interfaces, e.g. works by Myron Krueger and my own earlier piece Riviera in order to analyze their affective dynamics. Also, I review the different applications and programming paradigms involved in authoring such spaces (e.g. Real-time systems like Max/MSP/Jitter and EyeCon) and how to apply them in compliance with the design heuristics.

This thesis investigates the role of error-correcting codes in Distributed and Pervasive Computing. The main results are at the intersection of Security and Fault Tolerance for these environments. There are two primary areas that are explored in this thesis. 1. We have investigated protocols for large scale fault tolerant secure distributed storage. The two main concerns here are security and redundancy. In one arm of this research we developed SAFE, a distributed storage system based on a new protocol that offers a two-in-one solution to fault-tolerance and confidentiality. This protocol is based on cryptographic properties of error correction codes. In another arm, we developed esf, another prototype distributed persistent storage; esf facilitates seamless hardware extension of storage units, high resilience to loads and provides high availability. The main ingredient in its design is a modern class of erasure codes known as the {em Fountain Codes}. One problem in such large storage is the heavy overhead of the associated fingerprints needed for checking data integrity. esf deploys a clever integrity check mechanism by use of a data structure known as the {em Merkle Tree} to address this issue. 2. We also investigated the design of a new remote authentication protocol. Applications over long range wireless would benefit quite a bit from this design. We designed and implemented LAWN, a lightweight remote authentication protocol for wireless networks that deploys a randomized approximation scheme based on Error correcting codes. We have evaluated in detail the performance of LAWN; while it adds very low overhead of computation, the savings in bandwidth and power are quite dramatic.

A certificate based approach is proposed for access control operations of context aware systems for multi domain environments. New model deals with the removal of inter-domain communication requirement in access request evaluation process. The study is applied on a prototype implementation with configuration for two dierent cases to show the applicability of the proposed certificate based, context aware access control model for multi domain environments. The outputs for the cases show that proposed access control model can satisfy the requirements of a context aware access control model while removing inter domain communication needs which may cause some latency in access request evaluation phase.

Potentially transformational ideas in several applications of human and computer interaction form the motivation for this work. It is targeted towards a systematic approach to the design of systems with complex, intelligent and interactive exchange of information between a system and the environment it is meant to monitor, and gather knowledge about. The Pahl and Beitz systematic design method is modified with the inclusion of generic sub-systems from Living Systems Theory, modeling and simulation tools and other adaptations within the context of the validation square to synthesize a design method for the design of systems with intelligent and interactive information flow. The validation of the proposed design method is carried out with the aid of an example wherein a motion capture system is designed based on the Nintendo Wii Remote(TM). Results include an evaluation of the performance of a prototype as well as the design method itself in the context of the requirements that the method must fulfill.

<p>The research presented in this thesis investigates the design challenges associated with the development and use of mobile applications and tools for supporting collaboration in educational activities. These technologies provide new opportunities to promote and enhance collaboration by engaging learners in a variety of activities across different places and contexts. A basic challenge is to identify how to design and deploy mobile tools and services that could be used to support collaboration in different kinds of settings. There is a need to investigate how to design collaborative learning processes and to support flexible educational activities that take advantage of mobility. The main research question that I focus on is the identification of factors that influence the design of mobile collaborative learning.</p><p>The theoretical foundations that guide my work rely on the concepts behind computer supported collaborative learning and design-based research. These ideas are presented at the beginning of this thesis and provide the basis for developing an initial framework for understanding mobile collaboration. The empirical results from three different projects conducted as part of my efforts at the Center for Learning and Knowledge Technologies at Växjö University are presented and analyzed. These results are based on a collection of papers that have been published in two refereed international conference proceedings, a journal paper, and a book chapter. The educational activities and technological support have been developed in accordance with a grounded theoretical framework. The thesis ends by discussing those factors, which have been identified as having a significant influence when it comes to the design and support of mobile collaborative learning.</p><p>The findings presented in this thesis indicate that mobility changes the contexts of learning and modes of collaboration, requiring different design approaches than those used in traditional system development to support teaching and learning. The major conclusion of these efforts is that the learners’ creations, actions, sharing of experiences and reflections are key factors to consider when designing mobile collaborative activities in learning. The results additionally point to the benefit of directly involving the learners in the design process by connecting them to the iterative cycles of interaction design and research.</p>