Supporting service discovery, querying and interaction in ubiquitous computing environments.

In this paper, we contend that ubiquitous computing environments will be highly heterogeneous, service rich domains. Moreover, future applications will consequently be required to interact with multiple, specialised service location and interaction protocols simultaneously. We argue that existing service discovery techniques do not provide sufficient support to address the challenges of building applications targeted to these emerging environments. This paper makes a number of contributions. Firstly, using a set of short ubiquitous computing scenarios we identify several key limitations of existing service discovery approaches that reduce their ability to support ubiquitous computing applications. Secondly, we present a detailed analysis of requirements for providing effective support in this domain. Thirdly, we provide the design of a simple extensible meta-service discovery architecture that uses database techniques to unify service discovery protocols and addresses several of our key requirements. Lastly, we examine the lessons learnt through the development of a prototype implementation of our architecture

Multi-Device Design in Contexts of Interchange and Task Migration

Com a miniaturização dos componentes digitais e o vasto desenvolvimento tecnológico dos últimos anos, a sociedade tem presenciado a redefinição dos "computadores pessoais" pelo advento dos dispositivos móveis. Além da inovação, eles introduziram o desafio do design multi-dispositivo para as aplicações desktop. Enquanto algumas abordagens criaram interfaces móveis sem aproveitar qualquer modelo, outras buscaram adaptações automáticas visando reduzir a sobrecarga de designo Em ambas, o foco do design deixou de ser o usuário, tornando as interfaces tão diferentes ao ponto de comprometerem a usabilidade na realização de uma mesma tarefa em vários dispositivos. Esta tese afirma que não existe uma abordagem de design multi-dispositivo capaz de garantir boa usabilidade em todos os contextos porque o usuário pode escolher apenas uma forma de acesso à aplicação ou alternar seu uso por meio de vários dispositivos. No primeiro caso, o usuário aprende a usar a interface para realizar suas tarefas, sendo relevante uma abordagem que aproveite os recursos do dispositivo e trate suas limitações. No segundo, o usuário já conhece uma das interfaces, o que gera uma expectativa no uso das demais. Logo, é necessário combinar abordagens com objetivos diferentes para atender ao usuário de acordo com o seu contexto de uso. Neste sentido, propõe-se o design multi-dispositivo por meio da preservação de uma hierarquia de prioridades de consistência definida em três níveis. Enquanto os dois primeiros dão suporte à expectativa do usuário em contextos de uso alternado (propensos à execução de tarefas em dispositivos diferentes) e migração de tarefas (iniciando tarefas com um dispositivo e concluindo com outro), o terceiro nível garante a personalização das tarefas de maior interesse visando eficiência e satisfação de uso em um dispositivo específico. A avaliação desta metodologia foi feita por meio de um experimento com três interfaces de pocket PC construídas a partir de uma aplicação desktop do domínio de Educação a Distância: a primeira delas era uma réplica da original (Migração Direta), a segunda não mantinha consistência de layout e era baseada em um processo de design personalizado adequado ao dispositivo (Linear) e a terceira aplicava apenas os dois primeiros níveis da hierarquia de prioridades (Overview). Os resultados da avaliação subjetiva mostraram que a abordagem Overview foi capaz de manter o modelo mental do usuário com maior precisão por preservar os atributos de facilidade, eficiência e segurança de uso na interação inter-dispositivo. Além disso, os resultados medidos para a eficácia (exatidão das respostas) e eficiênciá (tempo médio de execução das tarefas) foram iguais ou melhores com essa abordagem. Por outro lado, os usuários revelaram uma preferência pela personalização de tarefas presente na abordagem Linear. Este resultado dá suporte à proposta desta tese, mostrando que a eficácia gerada pelos dois primeiros níveis da hierarquia de prioridades (percepção e execução das tarefas) deve ser combinada com o terceiro nível de personalização. Para isso, sugere-se a disponibilização de padrões de interface criados pelo designer para escolha do usuário durante a interação. Essa combinação deve garantir usabilidade no acesso a uma aplicação feito sempre por um mesmo dispositivo ou em contextos de uso alternado e migração de tarefasWith the miniaturization of digital components and the vast technological development of the past years, society has remarked the redefinition of "personal computers" by the advent of modern mobile devices. Besides the innovation, these handhelds also introduced the challenge to develop multi-device interfaces for today's desktop applications. While some created mobile interfaces from scratch to get the best from the devices, others looked for automatic adaptations to reduce the load imposed to the designeI. In both cases, the user wasn't the focus anymore, which resulted interfaces so different from each other to the point of compromising usability when peHorming one task on many devices. This thesis claims that there is no multi-device approach capable to provi de full usability in every context because the user may choose only one interface to access the application or interchange its use via many devices. In the first case, the user learns to perform tasks with the given device, which makes relevant an approach that takes advantage of its resources and solves its limitations. In the second, the user already knows one of the available interfaces, which generates an expectation for the others. Therefore, it is necessary to combine approaches with different goals and suit the user according to the appropriate context. In this sense, we propose multi-device design via maintenance of a consistency priorities hierarchy defined in three levels. The first two levels give support to the user's expectation in contexts of interchange (prone to task execution with different devices) and task migration (starting tasks with one device and finishing with other). On the other side, the third level provides task personalization according to the user's interest towards higher efficiency and satisfaction of use with a specific device. The evaluation of this methodology was conducted by an experiment with three pocket PC interfaces designed from an e-learning desktop application: the first interface was an exact replica of the original desktop version (Direct Migration), the second didn't maintain layout consistency and was based in a personalized design process adequate to the device (Linear) while the third applied only the first two levels of the consistency priorities hierarchy (Overview). The subjective evaluation results pointed the Overview approach as the best to maintain the user's mental model by preserving easiness, efficiency and safety of use on inter-device interaction. Additionally, both measured efficacy (task result accuracy) and efficiency (task execution mean time) were the same or even better with this approach. On the other hand, users revealed their preference for the task personalization present in the Linear approach. This result gives support to our proposal, corroborating that the efficacy generated by the first two levels of the consistency priorities hierarchy (task perception and execution) should be combined with the third level of personalization. This could be done by letting designers create interface patterns and make them available to users during interaction. Such combination should guarantee usability while constantly accessing one application through the same device or in contexts of alternated use and task migratio

Enhanced Indoor Localization System based on Inertial Navigation

An algorithm for indoor localization of pedestrians using an improved Inertial Navigation system is presented for smartphone based applications. When using standard inertial navigation algorithm, errors in sensors due to random noise and bias result in a large drift from the actual location with time. Novel corrections are introduced for the basic system to increase the accuracy by counteracting the accumulation of this drift error, which are applied using a Kalman filter framework. A generalized velocity model was applied to correct the walking velocity and the accuracy of the algorithm was investigated with three different velocity models which were derived from the actual velocity measured at the hip of walking person. Spatial constraints based on knowledge of indoor environment were applied to correct the walking direction. Analysis of absolute heading corrections from magnetic direction was performed . Results show that the proposed method with Gaussian velocity model achieves competitive accuracy with a 30\% less variance over Step and Heading approach proving the accuracy and robustness of proposed method. We also investigated the frequency of applying corrections and found that a 4\% corrections per step is required for improved accuracy. The proposed method is applicable in indoor localization and tracking applications based on smart phone where traditional approaches such as GNSS suffers from many issues

Network Simulation Cradle

This thesis proposes the use of real world network stacks instead of protocol abstractions in a network simulator, bringing the actual code used in computer systems inside the simulator and allowing for greater simulation accuracy. Specifically, a framework called the Network Simulation Cradle is created that supports the kernel source code from FreeBSD, OpenBSD and Linux to make the network stacks from these systems available to the popular network simulator ns-2. Simulating with these real world network stacks reveals situations where the result differs significantly from ns-2's TCP models. The simulated network stacks are able to be directly compared to the same operating system running on an actual machine, making validation simple. When measuring the packet traces produced on a test network and in simulation the results are nearly identical, a level of accuracy previously unavailable using traditional TCP simulation models. The results of simulations run comparing ns-2 TCP models and our framework are presented in this dissertation along with validation studies of our framework showing how closely simulation resembles real world computers. Using real world stacks to simulate TCP is a complementary approach to using the existing TCP models and provides an extra level of validation. This way of simulating TCP and other protocols provides the network researcher or engineer new possibilities. One example is using the framework as a protocol development environment, which allows user-level development of protocols with a standard set of reproducible tests, the ability to test scenarios which are costly or impossible to build physically, and being able to trace and debug the protocol code without affecting results

Positioning algorithms for RFID-based multi-sensor indoor/outdoor positioning techniques

Position information has been very important. People need this information almost everywhere all the time. However, it is a challenging task to provide precise positions indoor/outdoor seamlessly. Outdoor positioning has been widely studied and accurate positions can usually be achieved by well developed GPS techniques. However, these techniques are difficult to be used indoor since GPS signals are too weak to be received. The alternative techniques, such as inertial sensors and radio-based pseudolites, can be used for indoor positioning but have limitations. For example, the inertial sensors suffer from drifting problems caused by the accumulating errors of measured acceleration and velocity and the radio-based techniques are prone to the obstructions and multipath effects of the transmitted signals. It is therefore necessary to develop improved methods for minimising the limitations of the current indoor positioning techniques and providing an adequately precise solution of the indoor positioning and seamless indoor/outdoor positioning. The main objectives of this research are to investigate and develop algorithms for the low-cost and portable indoor personal positioning system using Radio Frequency Identification (RFID) based multi-sensor techniques, such as integrating with Micro-Electro-Mechanical Systems (MEMS) Inertial Navigation System (INS) and/or GPS. A RFID probabilistic Cell of Origin (CoO) algorithm is developed, which is superior to the conventional CoO positioning algorithm in its positioning accuracy and continuity. Integration algorithms are also developed for RFID-based multi-sensor positioning techniques, which can provide metre-level positioning accuracy for dynamic personal positioning indoors. In addition, indoor/outdoor seamless positioning algorithms are investigated based on the iterated Reduced Sigma Point Kalman Filter (RSPKF) for RFID/MEMS INS/low-cost GPS integrated technique, which can provide metre-level positioning accuracy for personal positioning. 3-D GIS assisted personal positioning algorithms are also developed, including the map matching algorithm based on the probabilistic maps for personal positioning and the Site Specific (SISP) propagation model for efficiently generating the RFID signal strength distributions in location fingerprinting algorithms. Both static and dynamic indoor positioning experiments have been conducted using the RFID and RFID/MEMS INS integrated techniques. Metre-level positioning accuracy is achieved (e.g. 3.5m in rooms and 1.5m in stairways for static position, 4m for dynamic positioning and 1.7m using the GIS assisted positioning algorithms). Various indoor/outdoor experiments have been conducted using the RFID/MEMS INS/low-cost GPS integrated technique. It indicates that the techniques selected in this study, integrated with the low-cost GPS, can be used to provide continuous indoor/outdoor positions in approximately 4m accuracy with the iterated RSPKF. The results from the above experiments have demonstrated the improvements of integrating multiple sensors with RFID and utilizing the 3-D GIS data for personal positioning. The algorithms developed can be used in a portable RFID based multi-sensor positioning system to achieve metre-level accuracy in the indoor/outdoor environments. The proposed system has potential applications, such as tracking miners underground, monitoring athletes, locating first responders, guiding the disabled and providing other general location based services (LBS)

Investigation of Shadow Matching for GNSS Positioning in Urban Canyons

All travel behavior of people in urban areas relies on knowing their position. Obtaining position has become increasingly easier thanks to the vast popularity of ‘smart’ mobile devices. The main and most accurate positioning technique used in these devices is global navigation satellite systems (GNSS). However, the poor performance of GNSS user equipment in urban canyons is a well-known problem and it is particularly inaccurate in the cross-street direction. The accuracy in this direction greatly affects many applications, including vehicle lane identification and high-accuracy pedestrian navigation. Shadow matching is a new technique that helps solve this problem by integrating GNSS constellation geometries and information derived from 3D models of buildings. This study brings the shadow matching principle from a simple mathematical model, through experimental proof of concept, system design and demonstration, algorithm redesign, comprehensive experimental tests, real-time demonstration and feasibility assessment, to a workable positioning solution. In this thesis, GNSS performance in urban canyons is numerically evaluated using 3D models. Then, a generic two-phase 6-step shadow matching system is proposed, implemented and tested against both geodetic and smartphone-grade GNSS receivers. A Bayesian technique-based shadow matching is proposed to account for NLOS and diffracted signal reception. A particle filter is designed to enable multi-epoch kinematic positioning. Finally, shadow matching is adapted and implemented as a mobile application (app), with feasibility assessment conducted. Results from the investigation confirm that conventional ranging-based GNSS is not adequate for reliable urban positioning. The designed shadow matching positioning system is demonstrated complementary to conventional GNSS in improving urban positioning accuracy. Each of the three generations of shadow matching algorithm is demonstrated to provide better positioning performance, supported by comprehensive experiments. In summary, shadow matching has been demonstrated to significantly improve urban positioning accuracy; it shows great potential to revolutionize urban positioning from street level to lane level, and possibly meter level

Coordinated adaptation for adaptive context-aware applications

The ability to adapt to change is critical to both mobile and context-aware applications. This thesis argues that providing sufficient support for adaptive context-aware applications requires support for coordinated adaptation. Specifically, the main argument of this thesis is that coordinated adaptation requires applications to delegate adaptation control to an entity that can receive state information from multiple applications and trigger adaptation in multiple applications. Furthermore, coordination requires support for reconfiguration of the adaptive behaviour and user involvement. Failure to support coordinated adaptation is shown to lead to poor system and application performance and insufficient support for user requirements. An investigation of the existing state-of-the-art in the areas of adaptive and context- aware systems and an analysis of the limitations of existing systems leads to the establishment of a set of design requirements for the support of coordinated adaptation. Specifically, adaptation control should be decoupled from the mechanisms implementing the adaptive behaviour of the applications, applications should externalise both state information and the adaptive mechanisms they support and the adaptation control mechanism should allow modifications without the need for re-implementation of either the application or the support platform. This thesis presents the design of a platform derived from the aforementioned re- quirements. This platform utilises a policy based mechanism for controlling adaptation. Based on the particular requirements of adaptive context-aware applications a new pol- icy language is defined derived from Kowalsky’s Event Calculus logic programming formalism. This policy language allows the specification of policy rules where condi- tions are defined through the expression of temporal relationships between events and entities that represent duration (i.e. fluents). A prototype implementation of this design allowed the evaluation of the features offered by this platform. This evaluation reveals that the platform can support coordinated adaptation with acceptable performance cost.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Recent Developments on Mobile Ad-Hoc Networks and Vehicular Ad-Hoc Networks

This book presents collective works published in the recent Special Issue (SI) entitled "Recent Developments on Mobile Ad-Hoc Networks and Vehicular Ad-Hoc Networks”. These works expose the readership to the latest solutions and techniques for MANETs and VANETs. They cover interesting topics such as power-aware optimization solutions for MANETs, data dissemination in VANETs, adaptive multi-hop broadcast schemes for VANETs, multi-metric routing protocols for VANETs, and incentive mechanisms to encourage the distribution of information in VANETs. The book demonstrates pioneering work in these fields, investigates novel solutions and methods, and discusses future trends in these field