Utilizing context information and in networks, enabling network services to act upon context information, and exchanging context information with applications, constitutes an important new approach to designing communication systems and central to the research project named Ambient Networks. The Ambient Networks project is a part of the 6th Framework Project cofunded by the European Commission and carried out by industry and academia. A system is said to be context-aware when it reacts to changes in context i.e., information which describes an entity’s current situation. This new approach enables developments of systems that are more adaptive to user needs and behavior. As a result systems can provide a homogenous appearance which is important as more and more different network access technologies arise. This thesis investigates, models, implements, and evaluates a distributed context-aware architecture for Ambient Networks, the Distributed Context eXchange Protocol (DCXP). The solution is a proof-of-concept that shows how a context-aware ambient network can benefit from a distributed approach. The current design is based on a peer-to-peer architecture that forms an overlay to distribute context information among the participating units. This distributed approach was chosen in order to balance the load and also enable a device to easily locate and fetch desired context information. The evaluation of the proposed context-aware architecture addresses the issues of how such a system ties in with the ideas of Ambient Networks. The main result of this report is a prototype enabling nodes in an ambient network to exchange context information. Moreover, the results show that the prototype needs to be refined in order to work in larger scale networks. / Användning av miljö-beskrivande information, så kallad context information, i olika nätverk är en ny infallsvinkel i designen av kommunikationssystem och är av stor vikt i forskningsprojektet Ambient Networks. Målet är att context information ska kunna utnyttjas i nätverken av olika tjänster samt även dela informationen med applikationer. Ambient Networks projektet är en del av det sjätte EU finansierade ramprogrammet där industrin och den akademiska världen deltar. Ett nätverk eller system klassificeras som context medvetet, context-aware, när det tar hänsyn till förändringar i sk. context information. Context information eller miljö-beskrivande information beskriver en enhets nuvarande situation. Detta möjliggör utveckling av system som ”lyssnar” på användaren och anpassar sig efter dess behov och beteende. Ett praktiskt exempel skulle kunna vara att användare upplever det som ett homogent system trots att det finns flera underliggande access teknologier. Den här uppsatsen undersöker, designar, implementerar och utvärderar en distribuerad context-aware arkitektur för Ambient Networks, Distributed Context eXchange Protocol (DCXP). Lösningen visar hur ett ambient network kan nyttja en distribuerad lösning för att hantera context information. Designen bygger på att de deltagande noderna skapar ett virtuellt nät, overlay, för att mellan sig dela på context informationen. Den här lösningen valdes för att balansera belastningen jämt mellan de deltagande noderna samt att på ett enkelt sätt för varje enskild node kunna lokalisera och hämta önskad context information. Utvärdering av den föreslagna lösningen visar på hur den kan integreras med den övriga utvecklingen som skett inom Ambient Networks projektet. Det huvudsakliga resultatet av arbetet är en prototyp som möjliggör för noder i ett ambient nätverk att utbyta context information. Vidare visar även resultatet att prototypen bör vidareutvecklas för att fungera i större sammanhang.

Emerging wireless networks are foreseen as an integration of heterogeneous spectrum bands, wireless access technologies, and backhaul solutions, as well as a large-scale interconnection of devices, people, and vehicles. Such a heterogeneity will range from the proliferation of multi-tasking user devices with different capabilities such as smartphones and tablets to the deployment of multi-mode access points that can operate over heterogeneous frequency bands spanning both sub-6 GHz microwave and high-frequency millimeter wave (mmW) frequencies bands. This heterogeneous ecosystem will yield new challenges and opportunities for wireless resource management. On the one hand, resource management can exploit user and network-specific context information, such as application type, social metrics, or operator pricing, to develop application-driven, context-aware networks. Similarly, multiple frequency bands can be leveraged to meet the stringent and heterogeneous quality-of-service (QoS) requirements of the new wireless services such as video streaming and interactive gaming. On the other hand, resource management in such heterogeneous, multi-band, and large-scale wireless systems requires distributed frameworks that can effectively utilize all available resources while operating with manageable overhead. The key goal of this dissertation is therefore to develop novel, self-organizing, and low-complexity resource management protocols -- using techniques from matching theory, optimization, and machine learning -- to address critical resource allocation problems for emerging heterogeneous wireless systems while explicitly modeling and factoring diverse network context information. Towards achieving this goal, this dissertation makes a number of key contributions. First, a novel context-aware scheduling framework is developed for enabling dual-mode base stations to efficiently and jointly utilize mmW and microwave frequency resources while maximizing the number of user applications whose stringent delay requirements are satisfied. The results show that the proposed approach will be able to significantly improve the QoS per application and decrease the outage probability. Second, novel solutions are proposed to address both network formation and resource allocation problems in multi-hop wireless backhaul networks that operate at mmW frequencies. The proposed framework motivates collaboration among multiple network operators by resource sharing to reduce the cost of backhauling, while jointly accounting for both wireless channel characteristics and economic factors. Third, a novel framework is proposed to exploit high-capacity mmW communications and device-level caching to minimize handover failures as well as energy consumption by inter-frequency measurements, and to provide seamless mobility in dense heterogeneous mmW-microwave small cell networks (SCNs). Fourth, a new cell association algorithm is proposed, based on matching theory with minimum quota constraints, to optimize load balancing in integrated mmW-microwave networks. Fifth, a novel medium access control (MAC) protocol is proposed to dynamically manage the wireless local area network (WLAN) traffic jointly over the unlicensed 60 GHz mmW and sub-6 GHz bands to maximize the saturation throughput and minimize the delay experienced by users. Finally, a novel resource management approach is proposed to optimize device-to-device (D2D) communications and improve traffic offload in heterogeneous wireless SCNs by leveraging social context information that is dynamically learned by the network. In a nutshell, by providing novel, context-aware, and self-organizing frameworks, this dissertation addresses fundamentally challenging resource management problems that mainly stem from large scale, stringent service requirements, and heterogeneity of next-generation wireless networks. / Ph. D. / The emergence of bandwidth-intensive applications along with vast proliferation of smart, multi-tasking handhelds have strained the capacity of wireless networks. Furthermore, the landscape of wireless communications is shifting towards providing connectivity, not only to humans, but also to automated cars, drones, and robots, among other critical applications. These new technologies will enable devices, machines, and things to be more intuitive, while being more capable, in order to improve the quality of life for human. For example, in future networked life, smartphones will predict our needs and help us with providing timely and relevant information from our surrounding. As an another example, autonomous vehicles and smart transportation systems with large number of connected safety features will minimize road incidents and yield a safe and joyful driving experience. Turning such emerging services into reality will require new technology innovations that provide high efficiency and substantial levels of scalability. To this end, wireless communication is the key candidate to provide large-scale and ubiquitous connectivity. However, existing wireless networks operate at congested microwave (µW) frequency bands and cannot manage the exponential growth in wireless data traffic or support low latency and ultra-high reliability communications, required by many emerging critical applications. Therefore, the goal of this dissertation is to develop novel network resource utilization frameworks to efficiently manage the heterogeneous traffic in next-generation wireless networks, while meeting their stringent quality-of-service (QoS) requirements. This transformative, fundamental research will expedite the deployment of communications at very high frequencies, at the millimeter wave (mmW) frequency bands, in next-generation wireless networks. The developed frameworks will advance new concepts from matching theory and machine learning for resource management in cellular networks, wireless local area networks (WLANs), and the intersection of these systems at both mmW and µW unlicensed frequency bands. This multi-band networking will leverage the synergies between mmW and µW wireless networks to provide robust and cost-effective solutions that enable the support of heterogeneous traffic from future wireless services. The anticipated results will transform the way in which spectral and time resources are used in both cellular networks and WLANs.

Aplicações sensíveis a contexto utilizam informações de contexto para fornecer serviços adaptados a usuários na realização de suas tarefas. Informação de contexto é qualquer informação considerada relevante para caracterizar entidades de uma interação usuário-computador, como a identidade e a localização de usuários. Esta tese trata a carência de uma abordagem que considere, em termos de processo de software, a complexidade de desenvolvimento de software sensível a contexto. O problema em questão é tratado por meio de três linhas de investigação: modelagem de informação contextual, serviços para tratamento de informação contextual e processo de software para computação sensível a contexto. As contribuições desta tese incluem: (i) o processo de software POCAp (Process for Ontological Context-aware Applications) para apoiar a construção de aplicações sensíveis a contexto baseadas em ontologias; (ii) o modelo de informações de contexto SeCoM (Semantic Context Model) baseado em ontologias e em padrões da Web Semântica; (iii) a infra-estrutura de serviços configuráveis SCK (Semantic Context Kernel) para interpretar informações de contexto apoiadas por modelos ontológicos de informação contextual, como o modelo SeCoM; (iv) uma instanciação do processo POCAp correspondente à extensão de uma aplicação com informações de contexto apoiadas pelo modelo SeCoM, e sua integração com serviços da infra-estrutura SCK; e (v) a identificação de questões de projeto relacionadas à inferência sobre informação contextual ontológica / In order to provide adaptive services according to users? tasks, context-aware applications exploit context information, which is any information used to characterize entities of a user-computer interaction such as user identity or user location. This thesis deals with the lack of a software process-based approach to supporting the inherent complexity of developing context-aware systems. The work reported in this thesis followed three main lines of investigation: context information modeling, services for processing context information, and a software process for context-aware computing. The contributions of this thesis include: (i) the Process for Ontological Context-aware Applications (POCAp) to support the development of context-aware applications based on ontologies; (ii) the Semantic Context Model (SeCoM) based on Semantic Web standards and ontologies; (iii) the Semantic Context Kernel (SCK) services infrastructure for interpreting ontological context information models such as the SeCoM model; (iv) an implementation of the POCAp process for the extension of an application with context information based on the SeCoM model, and its integration with services of the SCK infrastructure; and (v) the identification of design issues related to the inference over ontology-based context information

Submitted by Jaqueline Silva (jtas29@gmail.com) on 2014-09-23T16:48:32Z No. of bitstreams: 2 Bastos, Alexsandro Beserra-2013-dissertação.pdf: 1520807 bytes, checksum: 5001709fca398fc1b01bbc57b11c8b76 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2014-09-23T18:07:56Z (GMT) No. of bitstreams: 2 Bastos, Alexsandro Beserra-2013-dissertação.pdf: 1520807 bytes, checksum: 5001709fca398fc1b01bbc57b11c8b76 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-09-23T18:07:56Z (GMT). No. of bitstreams: 2 Bastos, Alexsandro Beserra-2013-dissertação.pdf: 1520807 bytes, checksum: 5001709fca398fc1b01bbc57b11c8b76 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2013-10-21 / Monitoring vital signs in intensive care units (ICU) is an everyday activity of various health professionals, including doctors, nurses, technicians and nursing assistants. In most ICUs, monitoring and recording vital signs are performed in a manual fashion and in predefined time instants. The records of measurements of vital signs in ICUs are generally written on preprinted forms, and a health professional has to re-sort those forms when he wants to get some information about the clinical state of a patient. Besides, when an abnormal measurement of vital sign is detected, a multiparameter monitor triggers audible alarms, and that alarm may not be prompted detected by the medical staff, depending on the workflow within an ICU. In that sense, this work proposes a knowledge representation model of monitoring of vital signs of patients in ICUs. The model proposed exploits the expressiveness and the formality of ontologies, rules and semantic web technologies. This promotes the consensual comprehension, the sharing and the reuse of vital signs of patients. The aim is to develop context-aware applications for monitoring human vital signs, including the storage, query support and semantic alarms triggering. / O monitoramento de sinais vitais de pacientes em unidades de terapia intensiva (UTI) é uma atividade que faz parte da rotina de vários profissionais da área da Saúde, envolvendo médicos, enfermeiros, técnicos e auxiliares de enfermagem. Em várias UTIs, o acompanhamento e o registro dos monitoramentos de sinais vitais são realizados de forma manual e em instantes de tempo pré-definidos. Nesse cenário, os registros das medições dos sinais vitais são escritos em formulários pré-impressos, e quando um profissional da saúde deseja obter alguma informação sobre o estado clínico de um paciente, ele tem que recorrer a esses formulários. Além disso, quando ocorre alguma anormalidade no monitoramento do sinal vital do paciente, um monitor multiparamétrico emite alarmes sonoros e, dependendo do fluxo de trabalho dentro da UTI, esse alarme pode não ser percebido prontamente pela equipe médica. Nesse sentido, este trabalho propõe um modelo de representação do conhecimento relativo ao monitoramento de sinais vitais de pacientes em UTIs. O modelo proposto utiliza o potencial de expressividade e formalidade de ontologias, regras e tecnologias correlatas da Web Semântica, o que promove a compreensão consensual, o compartilhamento e a reutilização de informações de sinais vitais de pacientes. Com esse modelo, espera-se também viabilizar o desenvolvimento de aplicações sensíveis a contexto que envolvem o monitoramento de sinais vitais humanos, com armazenamento, consultas e produção de alarmes em casos de anormalidades detectadas nas medições desses sinais.

Este trabalho apresenta um sistema neural modular, que processa separadamente informações de contexto espacial e temporal, para a tarefa de reprodução de sequências temporais. Para o desenvolvimento do sistema neural foram considerados redes neurais recorrentes, modelos estocásticos, sistemas neurais modulares e processamento de informações de contexto. Em seguida, foram estudados três modelos com abordagens distintas para aprendizagem de seqüências temporais: uma rede neural parcialmente recorrente, um exemplo de sistema neural modular e um modelo estocástico utilizando a teoria de modelos markovianos escondidos. Com base nos estudos e modelos apresentados, esta pesquisa propõe um sistema formado por dois módulos sucessivos distintos. Uma rede de propagação direta (módulo estimador de contexto espacial) realiza o processamento de contexto espacial identificando a seqüência a ser reproduzida e fornecendo um protótipo do contexto para o segundo módulo. Este é formado por uma rede parcialmente recorrente (módulo de reprodução de sequências temporais) para aprender as informações de contexto temporal e reproduzir em suas saídas a seqüência identificada pelo módulo anterior. Para a finalidade mencionada, este mestrado utiliza a distribuição de Gibbs na saída do módulo para contexto espacial de forma que este forneça probabilidades de contexto espacial, indicando o grau de certeza do módulo e possibilitando a utilização de procedimentos especiais para os casos de dúvida. O sistema neural foi testado em conjuntos contendo trajetórias abertas, fechadas, e com diferentes situações de ambigüidade e complexidade. Duas situações distintas foram avaliadas: (a) capacidade do sistema em reproduzir trajetórias a partir de pontos iniciais treinados; e (b) capacidade de generalização do sistema reproduzindo trajetórias considerando pontos iniciais ou finais em situações não treinadas. A situação (b) é um problema de difícil ) solução em redes neurais devido à falta de contexto temporal, essencial na reprodução de seqüências. Foram realizados experimentos comparando o desempenho do sistema modular proposto com o de uma rede parcialmente recorrente operando sozinha e um sistema modular neural (TOTEM). Os resultados sugerem que o sistema proposto apresentou uma capacidade de generalização significamente melhor, sem que houvesse uma deterioração na capacidade de reproduzir seqüências treinadas. Esses resultados foram obtidos em sistema mais simples que o TOTEM. / This work presents a new modular neural system to deal separately with spatial and temporal context information, during temporal sequence processing. Given the initial and final states of the sequence, the neural system can reproduce the whole sequence linking these points. The proposed model involves concepts on recurrent neural networks, stochastic models, modular neural systems and context information processing. Three models based on distinct approaches to learn temporal sequences were particularly important in this work: a partially recurrent neural network, a modular neural system and a stochastic model based on the Hidden Markov Models theory. This master thesis presents a new modular neural system composed of two supervised neural networks. A feedforward neural network (spatial context estimator) to identify the desired sequence to be reproduced and to provide a spatial context prototype to the second module. This is a partially recurrent neural network to reproduce the sequence identified by the former module. Moreover, the first module employs the Gibbs distribution in the spatial context estimator outputs in such a way to obtain the uncertainty of the sequence identification task. Thus, with these probability values, special procedures may be used whenever a doubt occurs. The proposed system was evaluated in different domains containing open and closed sequences with different levels of complexity due to space dimension and level of ambiguity of the trained trajectories. The system was evaluated according to its ability to reproduce the sequence whenever versions of the initial and final points are provided. A version may be exactly the points seen during the training stage or points trained as intermediate states. The latter is considered a difficult task for recurrent neural networks due to the lack of temporal context information. Experiments were done comparing the performance of the proposed modular neural system with the performance of a recurrent neural network itself and a modular neural system (a model called TOTEM) for sequence reproduction. The results suggest that the proposed modular neural system presented ability to generalize significant1y better that of the recurrent neural network without deteriorating its ability to reproduce sequences starting from trained situations. The neural system may reproduce the results of the TOTEM with a simpler topology.

Aplicações sensíveis a contexto utilizam informações de contexto para fornecer serviços adaptados a usuários na realização de suas tarefas. Informação de contexto é qualquer informação considerada relevante para caracterizar entidades de uma interação usuário-computador, como a identidade e a localização de usuários. Esta tese trata a carência de uma abordagem que considere, em termos de processo de software, a complexidade de desenvolvimento de software sensível a contexto. O problema em questão é tratado por meio de três linhas de investigação: modelagem de informação contextual, serviços para tratamento de informação contextual e processo de software para computação sensível a contexto. As contribuições desta tese incluem: (i) o processo de software POCAp (Process for Ontological Context-aware Applications) para apoiar a construção de aplicações sensíveis a contexto baseadas em ontologias; (ii) o modelo de informações de contexto SeCoM (Semantic Context Model) baseado em ontologias e em padrões da Web Semântica; (iii) a infra-estrutura de serviços configuráveis SCK (Semantic Context Kernel) para interpretar informações de contexto apoiadas por modelos ontológicos de informação contextual, como o modelo SeCoM; (iv) uma instanciação do processo POCAp correspondente à extensão de uma aplicação com informações de contexto apoiadas pelo modelo SeCoM, e sua integração com serviços da infra-estrutura SCK; e (v) a identificação de questões de projeto relacionadas à inferência sobre informação contextual ontológica / In order to provide adaptive services according to users? tasks, context-aware applications exploit context information, which is any information used to characterize entities of a user-computer interaction such as user identity or user location. This thesis deals with the lack of a software process-based approach to supporting the inherent complexity of developing context-aware systems. The work reported in this thesis followed three main lines of investigation: context information modeling, services for processing context information, and a software process for context-aware computing. The contributions of this thesis include: (i) the Process for Ontological Context-aware Applications (POCAp) to support the development of context-aware applications based on ontologies; (ii) the Semantic Context Model (SeCoM) based on Semantic Web standards and ontologies; (iii) the Semantic Context Kernel (SCK) services infrastructure for interpreting ontological context information models such as the SeCoM model; (iv) an implementation of the POCAp process for the extension of an application with context information based on the SeCoM model, and its integration with services of the SCK infrastructure; and (v) the identification of design issues related to the inference over ontology-based context information

This masters thesis project, "Occupancy Sensor System", was conducted at Kungliga Tekniska Högskolan (KTH), Stockholm, Sweden, during the period 2007-04-24 – 2007-12-17. The goal of the project was to design an occupancy sensor system that determines if there exists more than one person in a defined region. The output of this system is for use in a context-aware system at the KTH Center for Wireless Systems (Wireless@KTH). The system is important because there is a need for specific input to context-aware systems concerning occupancy of spaces and because this thesis has focused on a problem that enables new complex and interesting services. Additionally, the specific problem of determining not only occupancy, but if this occupancy is zero, one, many has not been widely examined previously. The significance of zero occupants indicating an empty room has already been recognized as having economic and environmental value in terms of heating, ventilating, air-conditioning, and lighting. However, there has not been an effort to differentiate between a person being alone or if more than one person is present. A context-aware system might be able to use this later information to infer that a meeting is taking place in a meeting room, a class taking place in a classroom or that an individual is alone in a conference room, class room, etc. Thus enabling context-aware services to change their behavior based upon the differences in these situations. An occupancy sensor system prototype was designed to monitor a boundary by using a thermal detector, gumstix computer, an analog to digital converter prototype board, laptop computer, and a context broker. The testing and evaluation of the system, proved it to be sound. However, there are still further improvements and tests to be made. These improvements include: dynamic configuration of the system, communication between the different system entities, detection algorithms, and code improvements. Tests measuring accuracy of a detection algorithm and determining optimal detector placement need to be performed. The next step is to design applications that use the context information provided from the occupancy sensor system and expand the system to use multiple detectors. / Examensarbetet "Occupancy Sensor System" genomfördes på Kungliga Tekniska Högskolan (KTH), Stockholm, Sverige, under perioden 2007-04-24 – 2007-12-17. Målet med examensarbetet var att designa ett sensorsystem, som avgör om ett rum är befolkat med fler än en person i ett definierat område. Resultatet av detta system är till för användning i ett kontextmedvetet system som finns i KTH Center for Wireless Systems (Wireless@KTH). Systemet är viktigt eftersom det finns ett behov för specifik input till kontextmedvetna system som berör befolkning av rum och eftersom detta examensarbete har fokuserat på ett problem som möjliggör nya komplexa och intressanta tjänster. Dessutom har det inte tidigare undersökts i vidare bemärkelse hur man kan avgöra om ett rum befolkats av noll, en eller flera personer. Betydelsen av att ett rum är obefolkat har redan ansetts ha ekonomiskt och miljöbetingat värde vad gäller uppvärming, ventilation, luftkonditionering och belysning. Däremot har det inte gjorts ansträngningar att differentiera mellan att en ensam person eller flera är närvarande. Ett kontextmedvetet system skulle kunna använda den senare nämnda informationen för att dra slutsatsen att ett möte pågår i ett mötesrum, en lektion är igång i ett klassrum o.s.v. Detta möjliggör i sin tur för kontextmedvetna tjänster att ändra på sina beteenden baserat på skillnaderna i dessa situationer. En prototyp utvecklades för att övervaka en gräns genom användningen av en termisk detektor, gumstixdator, analog till digital signalkonverterare, bärbar dator och en context broker (kontextförmedlare). Testningar och utvärderingar av systemet visade att systemet var dugligt. Flera förbättringar och tester behöver dock göras i framtiden. Dessa förbättringar inkluderar: dynamisk konfiguration av systemet, kommunikation mellan de olika systementiteterna, detektionsalgoritmer och kodförbättringar. Återstående tester inkluderar mätning av en detektionsalgoritms tillförlitlighet samt optimal placering av detektorer. Nästa steg är att utveckla applikationer som använder kontextinformationen från systemet samt att utveckla systemet till att kunna använda flera detektorer.

Diversos pesquisadores vêm investigando métodos e técnicas para tornar possível às pessoas anotarem vídeos de modo transparente. A anotação pode ser realizada com a fala, com o uso de tinta digital ou algum outro meio que possa ser capturado enquanto a pessoa assiste ao vídeo. Tais anotações podem ser compartilhadas com outras pessoas, que podem estar assistindo ao mesmo vídeo em um mesmo instante ou em momentos diferentes, sendo interessante ainda que as anotações possam ser realizadas por várias pessoas de modo colaborativo. O paradigma Watch-and-Comment (WaC) propõe a captura transparente de anotações multimodais de usuários enquanto os mesmos assistem e comentam um vídeo. Como resultado desse processo, é gerado um vídeo digital interativo integrando o conteúdo original às anotações realizadas. Esta dissertação tem por objetivo explorar conceitos de computação ubíqua, redes sociais, redes peer-to-peer e TV interativa na proposta de um modelo arquitetural de ciência de informações de contexto para aplicações definidas segundo o paradigma WaC. O modelo explora a integração de um serviço ao paradigma, que auxilie ou forneça alternativas para que aplicações, do momento da captura ao acesso das anotações, utilizem informações de contexto do usuário, do vídeo e das anotações. O modelo também auxilia no estudo de colaboração entre usuários que realizam anotações em vídeos. Outra contribuição da dissertação é a prototipação de aplicações para avaliar e refinar o modelo proposto. São apresentadas extensões para a aplicação WaCTool, considerando o uso de redes sociais e de alternativas para a anotação em vídeos / Researchers have been investigating methods and techniques to allow people to annotate videos ubiquitously. Annotations can be made using voice, digital ink or some other media that can be captured while a person watches a video. These annotations can be shared with other people, who can be watching a video on the same time or at a different one. Also, these annotations can be made by many people collaboratively. The Watch-and-Comment (WaC) paradigm aims at capturing multimodal annotations in an ubiquitous way, while users watch and comment some video. As a result, an interactive digital video is generated combining the original content and the annotations. The work reported on this thesis explores concepts such as ubiquitous computing, social networks, peer-to-peer networks and interactive digital TV, to propose an architectural context-aware model to the applications defined by WaC paradigm. The model proposes the integration of a new service to the paradigm, supporting applications on the annotation process by offering capture alternatives and using context information from user, video and annotations. Also, the model provides a study in collaborative annotation process. Another contribution of this thesis is the prototypes built to evaluate and upgrade the proposed model. The prototypes are extensions from WaCTool, considering the use of social networks and alternatives to annotate in videos

[pt] Aplicações para o monitoramento de frotas de veículos e sistemas de logística, coordenação em situações de emergência, monitoramento ambiental ou de gestão de força de trabalho móvel podem usar redes móveis como meio de comunicação, troca de informações e de coordenação entre um número possivelmente grande de nós móveis interligados por uma rede WAN. A maioria desses sistemas requer o monitoramento em tempo real das informações de contexto dos nós móveis, interação com todos os nós participantes, bem como meios de adaptação num cenário muito dinâmico, onde não é possível prever quando, onde e por quanto tempo os nós permanecerão conectados. As soluções atuais ainda não têm recursos essenciais necessários para a comunicação com os nós móveis, tais como a entrega confiável de mensagens, suporte a handover, resistência a conectividade intermitente, mudanças de endereço IP e firewall transversal. Esta tese propõe um modelo de gestão de dados que permite a implantação de uma rede de componentes de provedores de dados com disseminação e transformação rápida e confiável de informações entre milhares de nós móveis interligados através de internet sem fio. Os testes de desempenho indicam que o nosso modelo consegue escalar para milhares de nós móveis e suporta disseminação confiável, rápida e com alta taxa de transferência da informação entre milhares de provedores de contexto e consumidores de contexto móveis. / [en] Applications such as vehicle fleet monitoring and logistic systems, emergency response coordination, environmental monitoring or mobile workforce management, employ mobile networks as means of communication, information sharing and coordination among a possibly very large set of mobile nodes interconnected by a Wide Area Network (WAN). The majority of those systems thus requires real-time tracking of the mobile nodes context information, interaction with all participant nodes, as well as means of adaptability in a very dynamic scenario, where it is not possible to predict when, where and for how long the nodes will remain connected. Despite being a subject of much research, current solutions still lack essential features required for communication with mobile nodes, such as reliable message delivery, handover support, resilience to intermittent connectivity, IP address changes and firewall transversal. This thesis proposes a data management model that enables deployment of a network of Data Provider components with reliable and on-time dissemination and transformation of information among thousands of mobile nodes interconnected through wireless internet. Performance tests indicate that our model scales to thousands of mobile nodes and supports reliable, high throughput and on-time data dissemination between several thousands of mobile Data Providers and Data Consumers.

Abstract The popularity of social networking services emphasises the importance of user communities. As the next evolutionary step, social networking will evolve towards user communities that are dynamically established according to contextual aspects such as the shared location and/or activities of people. In this vision, distributed peer-to-peer (P2P) technologies provide a respectable alternative to the centralised client-server technologies for implementing the upcoming community-centric mobile services. This thesis focuses on the development of enabling techniques and methods for a community-centric mobile service environment and on the evaluation of users’ perceptions and user acceptance of novel community-centric mobile services. The research was carried out by first examining the applicability of different P2P system architectures for implementing the management of user communities. Next, an experimental prototype of a community-centric mobile service environment was implemented. The experimental prototype was used for evaluating the performance of the community-centric mobile service environment and for conducting the user studies of novel community-centric mobile services. The evaluation was conducted in a real deployment environment with test users. The main results are the following: (1) a conceptual analysis of the advantages and disadvantages of P2P group management systems that are implemented using architecturally distinct P2P system architectures; (2) a performance evaluation of a P2P community management system, in which each community is implemented as an independent structured P2P overlay network; (3) a novel community-centric mobile service environment and its core component, a mobile middleware, which enables the use of P2P technologies and context information as part of Web-based applications running on a Web browser; (4) an evaluation of users’ perceptions and user acceptance of novel community-centric mobile services that are related to making a selection of an entertainment premise based on its music style and voting for music in a user community. / Tiivistelmä Käyttäjäyhteisöiden tärkeys on korostunut sosiaalista verkottumista edistävien palveluiden suosion kautta. Seuraavaksi sosiaalinen verkottuminen tulee laajentumaan yhteisöihin, jotka perustetaan dynaamisesti muun muassa ihmisten yhteisen sijainnin ja/tai toiminnan perusteella. Tulevaisuuden yhteisöllisten mobiilipalveluiden toteutuksessa hajautetut vertaisverkkoteknologiat tarjoavat varteenotettavan vaihtoehdon keskitetyille asiakas-palvelin -teknologioille. Tämä väitöskirjatyö keskittyy kehittämään tarvittavia tekniikoita ja menetelmiä yhteisöllisen mobiilipalveluympäristön toteuttamiseen sekä arvioimaan käyttäjien kokemuksia uusista yhteisöllisistä mobiilipalveluista. Tutkimuksessa tarkasteltiin aluksi arkkitehtuurillisesti erilaisten vertaisverkkojärjestelmien sopivuutta käyttäjäyhteisöjen hallinnan toteutettamiseksi. Seuraavaksi tutkimuksessa toteutettiin kokeellinen prototyyppi yhteisöllisestä mobiilipalveluympäristöstä. Kokeellista prototyyppiä hyödynnettiin sekä yhteisöllisen mobiilipalveluympäristön suorituskyvyn että uusien yhteisöllisten mobiilipalveluiden käyttäjäkokemuksen arvioinnissa. Arviointi suoritettiin aidossa käyttöympäristössä testikäyttäjien avulla. Väitöskirjatyön keskisimmät tulokset ovat seuraavat: (1) käsitteellinen analyysi arkkitehtuurillisesti erilaisten vertaisverkkojärjestelmien vahvuuksista ja heikkouksista ryhmänhallintajärjestelmän toteuttamisessa; (2) sellaisen yhteisönhallintajärjestelmän arviointi, jossa jokainen yhteisö on toteutettu erillisen ja itsenäisen rakenteellisen vertaisverkon avulla; (3) uusi yhteisöllinen mobiilipalveluympäristö, jonka keskeisin osa mobiili välikerrosohjelmisto mahdollistaa vertaisverkkoteknologioiden ja kontekstitiedon käyttämisen selaimessa toimivissa Web-sovelluksissa; (4) sellaisten uusien yhteisöllisten mobiilipalveluiden käyttäjäkokemuksen arviointi, jotka liittyvät vapaa-ajan viettopaikan valitaan musiikin perusteella ja soitettavan musiikin äänestämiseen käyttäjäyhteisöissä.