Dissertations / Theses on the topic 'Location-aware computing'

Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.
Includes bibliographical references (p. 89-90).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Indoor, location-aware devices have the potential to provide extremely useful resource and building information to human users; for example, a location-aware PDA could potentially provide map information in real time. We have developed a complete, extensible, indoor location-aware API to allow clients to interact with building and resource data stored on a central server. We have designed our own data model, emphasizing a space's adjacency relationships to other spaces as the most important relational characteristic. Route finding is a fundamental algorithm for the exploration of such a data model; we investigated, implemented, and evaluated several such algorithms. Furthermore, we have implemented both a server and several clients, demonstrating the robustness and reliability of the API. The API's most complex client, the CampusMap application, runs on a commodity graphics workstation and allows a user to interact with a full, three-dimensional model of campus. CampusMap generates lowest-cost routes between any campus location by interacting with a Location Server, visualizing campus spaces, and instantly updating route results.
by Jason Murray Bell.
M.Eng.

Abstract The development of mobile and ubiquitous computing has recently been rapid. One of the most promising research and development fields has been location-aware services. These services are challenging as they require a lot of resources for generating maps from spatial data and for visualizing temporary data gathered from the environment. Applying location-awareness and ubiquitous computing in the industry is currently under intensive research and development activities especially because of signs of promising new business opportunities. This thesis studies the development and evaluation of a location-aware system platform called Locawe designed for indoor and outdoor conditions. This decentralized middleware-based platform has been developed at CENTRIA Research and Development, Ylivieska. The main objectives of this research have been primarily to study and develop new ubiquitous features for the Locawe platform with various software and hardware combinations. In addition, during these studies gathered experiences have been used in order to design new versions of the Locawe architecture. These ubiquitous features, covering the use of GPS, RFID and WSAN technologies, have been tested in five field experiments, one laboratory experiment and several industrial pilots. In these evaluations, the author has considered what software and hardware alternatives are feasible and appropriate for improving the newly developed features in the Locawe platform. These features have been evaluated from usability, visualization and communication techniques perspective. As a result the author presents in this thesis main characteristics in location-aware system development from system layers, ubiquitous computing, mobility, and restrictions perspective. The author also suggests that the architeture presented in this thesis enables location-aware system development in indoor and outdoor conditions. With respect of state-of-the-art platforms, the Locawe platform is, at the moment, in some sense unique, although only as a research prototype. This platform combines two approaches, namely research on location platforms, and research on geosensor networks or smart environments. In addition, this platform gives one answer how RFID or WSAN technologies could be integrated under one framework together with mobile devices. Finally, the author also proposes that the research and development approach presented in this thesis can be applied successfully in research and development organizations specialized in applied research
Tiivistelmä Mobiilin ja sulautetun tietotekniikan kehitys on ollut viime aikoina nopeaa. Yksi lupaavimmista tutkimus- ja kehityskohteista on ollut paikkatietoiset palvelut. Näiden palveluiden kehittäminen on varsin haasteellista, koska kehittämistyö vaatii runsaasti resursseja sekä karttojen generoimisessa paikkatietoaineistoista että ympäristöstä kerättävän väliaikaisen tiedon visualisoinnissa. Paikkatietoisten sovellusten ja sulautetun tietotekniikan soveltaminen teollisuudessa on aktiivisen tutkimus- ja kehittämistoiminnan keskiössä, koska näköpiirissä on selvästi uusia lupaavia liiketoimintamahdollisuuksia. Tässä väitöskirjassa keskitytään Locawe-nimisen paikkatietoisen ohjelmistoalustan kehittämisen ja arvioinnin raportointiin. Locawe-alusta on suunniteltu sekä sisä- että ulko-olosuhteisiin. Tämä hajautettu väliohjelmistopohjainen alusta on kehitetty CENTRIA Tutkimus ja kehityksen Ylivieskan yksikössä. Väitöskirjan tavoitteena on ollut ensisijaisesti tutkia ja kehittää uusia, sulautettua tietotekniikkaa hyödyntäviä ominaisuuksia Locawe-alustaan hyödyntäen erilaisia ohjelmisto- ja laitteistokombinaatioita. Väitöskirjaan liittyvän tutkimustyön aikana käyttäjiltä on useaan otteeseen kerätty käyttökokemuksia. Kokemuksia on hyödynnetty Locawe-arkkitehtuurin seuraavien versioiden suunnittelussa. Uusia, sulautettua tietotekniikkaa hyödyntäviä ominaisuuksia on testattu kaikkiaan viidessä kenttätestissä, yhdessä laboratoriotestissä sekä useissa teollisissa piloteissa. Ominaisuuksien toteuttamisessa käytettiin GPS-, RFID- ja WSAN-teknologioita. Testeissä kirjoittaja arvioi, minkälaiset ohjelmisto- ja laitteistovaihtoehdot ovat toteuttamiskelpoisimpia ja soveliaimpia uusien ominaisuuksien kehittämiseksi Locawe-alustaan. Ominaisuuksia on arvioitu käytettävyyden, visualisoinnin ja viestintätekniikoiden näkökulmista. Tutkimustyön tuloksena kirjoittaja esittelee väitöskirjassa paikkatietoisten järjestelmien kehittämiseen liittyviä ominaispiirteitä järjestelmätasojen, sulautetun tietotekniikan, mobiliteetin ja rajoitteiden näkökulmista. Lisäksi kirjoittaja esittää väitöskirjassa arkkitehtuurin, joka mahdollistaa paikkatietoisen järjestelmän kehittämisen soveltuen niin sisä- kuin ulko-olosuhteisiin. Huomioiden paikkatietoisten alustojen tason maailmanlaajuisesti väitöskirjassa kuvattu Locawe-alusta on tutkimusprototyyppinäkin tällä hetkellä tietyssä määrin ainutlaatuinen. Alustan tutkimisessa on nimittäin keskitytty sekä paikkatietoisten alustojen että geosensoriverkkojen ja älykkäiden ympäristöjen tutkimiseen. Lisäksi Locawe-alusta tarjoaa yhden ratkaisun RFID ja WSAN teknologioiden integrointiin yhdeksi kehykseksi yhdessä mobiililaitteiden kanssa. Lopuksi kirjoittaja esittää, että väitöskirjassa esitetty tutkimus- ja kehittämistoiminnan lähestymistapaa voidaan soveltaa vastaavissa tutkimusorganisaatioissa kuin CENTRIA

Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.
Includes bibliographical references (p. 69-73).
In pervasive computing environments certain applications are interested in a user's location in order to provide a service. Such applications would benefit from an architecture that enables users to prove their location prior to requesting a service. We present PA C, an architecture for location-aware access control in pervasive computing environments, where users authenticate their location in order to gain access to resources. PAC preserves user anonymity and uses lightweight security. We evaluate our architecture with respect to its security and its scalability as the number of resources and users increase.
by Nikolaos Michalakis.
M.Eng.

In the post-PC era, mobile devices will replace desktops and become the main personal computer for many people. People rely on mobile devices such as smartphones and tablets for everything in their daily lives. A common requirement for mobile computing is wireless communication. It allows mobile devices to fetch remote resources easily. Unfortunately, the increasing demand of the mobility brings many new wireless management challenges such as security, energy-saving and location-awareness. These challenges have already impeded the advancement of mobile systems. In this dissertation we attempt to discover the guidelines of how to mitigate these problems through three general communication patterns in 802.11 wireless networks. We propose a cross-section of a few interesting and important enhancements to manage wireless connectivity. These enhancements provide useful primitives for the design of next-generation mobile systems in the future.;Specifically, we improve the association mechanism for wireless clients to defend against rogue wireless Access Points (APs) in Wireless LANs (WLANs) and vehicular networks. Real-world prototype systems confirm that our scheme can achieve high accuracy to detect even sophisticated rogue APs under various network conditions. We also develop a power-efficient system to reduce the energy consumption for mobile devices working as software-defined APs. Experimental results show that our system allows the Wi-Fi interface to sleep for up to 88% of the total time in several different applications and reduce the system energy by up to 33%. We achieve this while retaining comparable user experiences. Finally, we design a fine-grained scalable group localization algorithm to enable location-aware wireless communication. Our prototype implemented on commercial smartphones proves that our algorithm can quickly locate a group of mobile devices with centimeter-level accuracy.

Context-aware computing is a mobile computing paradigm in which applications can discover, use, and take advantage of contextual information, such as the location, tasks and preferences of the user, in order to adapt their behaviour in response to changing operating environments and user requirements. A problem that arises is the inability to respond to contextual information that cannot be classified into any known context. Many context-aware applications require all discovered contextual information to exactly match a type of context, otherwise the application will not react responsively. The ability to learn and recall contexts based on the contextual information discovered has not been very well addressed by previous context-aware applications and research. The aim of this thesis is to develop a component middleware technology for mobile computing devices for the discovery and capture of contextual information, using the situated reasoning concept of constructive memory. The research contribution of this thesis lies in developing a modified architecture for context-aware systems, using a constructive memory model as a way to learn and recall contexts from previous experiences and application interactions. Using a constructive memory model, previous experiences can be induced to construct potential contexts, given a small amount of learning and interaction. The learning process is able to map the many variations of contextual information currently discovered by the user with a predicted type of context based on what the application has stored and seen previously. It only requires a small amount of contextual information to predict a context, something common context-aware systems lack, as they require all information before a type of context is assigned. Additionally, some mechanism to reason about the contextual information being discovered from past application interactions will be beneficial to induce contexts for future experiences.

Master of Philosophy (Architecture)
Context-aware computing is a mobile computing paradigm in which applications can discover, use, and take advantage of contextual information, such as the location, tasks and preferences of the user, in order to adapt their behaviour in response to changing operating environments and user requirements. A problem that arises is the inability to respond to contextual information that cannot be classified into any known context. Many context-aware applications require all discovered contextual information to exactly match a type of context, otherwise the application will not react responsively. The ability to learn and recall contexts based on the contextual information discovered has not been very well addressed by previous context-aware applications and research. The aim of this thesis is to develop a component middleware technology for mobile computing devices for the discovery and capture of contextual information, using the situated reasoning concept of constructive memory. The research contribution of this thesis lies in developing a modified architecture for context-aware systems, using a constructive memory model as a way to learn and recall contexts from previous experiences and application interactions. Using a constructive memory model, previous experiences can be induced to construct potential contexts, given a small amount of learning and interaction. The learning process is able to map the many variations of contextual information currently discovered by the user with a predicted type of context based on what the application has stored and seen previously. It only requires a small amount of contextual information to predict a context, something common context-aware systems lack, as they require all information before a type of context is assigned. Additionally, some mechanism to reason about the contextual information being discovered from past application interactions will be beneficial to induce contexts for future experiences.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.
Includes bibliographical references (p. 87-89).
The Bluetooth specification describes a robust and powerful technology for short-range wireless communication. Unfortunately, the specification is immense and complicated, presenting a formidable challenge for novice developers. Currently, there is a lack of satisfactory technical documentation describing Bluetooth application development and the parts of the Bluetooth specification that are relevant to software developers. This thesis explains Bluetooth programming in the context of Internet programming and shows how most concepts in Internet programming are easily translated to Bluetooth. It describes how these concepts can be implemented in the GNU/Linux operating system using the BlueZ Bluetooth protocol stack and libraries. A Python extension module is presented that was created to assist in rapid development and deployment of Bluetooth applications. Finally, an inexpensive and trivially deployed infrastructure for location aware computing is presented, with a series of experiments conducted to determine how best to exploit such an infrastructure.
by Albert Shuyu Huang.
S.M.

This thesis presents an analytics platform for calculating spatio-temporal metrics in the context of geogames and context-based applications. It is based on an underlying conceptual model for spatio-temporal metrics, which consists of dimensions and variables to describe spatial and temporal phenomena, metrics functions to calculate application-relevant information and conditions using these data models, and actions to be triggered when certain conditions are met. The analytics platform is implemented as a cloud-based, distributed application that allows developers to define data requirements, collect required (client-generated) data, and define and execute spatio-temporal metrics. It is designed to handle large amounts of (streaming) data and to scale well under increasing amounts of data and metrics computations. The platform is validated in two experiments: a location-aware game for collecting noise data in a city and a mobile application for location-based mental health treatments, which shows its usability, versatility and feasibility in real-world scenario
Esta tesis presenta una plataforma de análisis para calcular métricas espacio-temporales en el contexto de geojuegos y aplicaciones basadas en el contexto. Se basa en un modelo conceptual para métricas espacio-temporales compuesto de dimensiones y variables para describir fenómenos con componentes espaciales y temporales, funciones de métricas para calcular información relevante para la aplicación, y acciones activadas cuando se cumplan ciertas condiciones. La implementación consiste en una aplicación distribuida basada en la nube que permite a los desarrolladores definir los requisitos de datos, recopilarlos en el cliente y ejecutar métricas espacio-temporales. Está diseñada para ser escalable en cuanto a los datos y al cómputo de las métricas. La plataforma está validada en dos experimentos: un geo-juego para recopilar datos de ruido en una ciudad y una aplicación móvil para tratamientos de salud mental basados en la ubicación, que muestra su usabilidad, versatilidad y viabilidad en escenarios del mundo real.

Location information is used to provide a diverse range of services to users such as emergency, navigation, billing, security, information and advertising services. This information is derived from a broad range of indoor and outdoor technologies. The location information thus derived is of different granularity, different co-ordination system and is controlled by numerous service providers. In addition to this, broad selections of devices are used for providing these services. Having a diverse range of applications requiring location information at different levels of granularity, the need to export location information across multiple devices and the existence of different location determination technologies necessitates the need for heterogeneous location network. These networks derive location information from multiple sources and provides various location-based services to users irrespective of the medium, device or technology used. Security, user privacy and management of location information are some of the important issues that need to be addressed. The main contribution of this thesis is the design of a secure and privacy assured heterogeneous location architecture. A formal methodology was chosen to design the heterogeneous location architecture. The design of the architecture resulted in a novel key distribution protocol and a model for information flow that can be easily encapsulated into applications or architectures having similar requirements. The research also resulted in the enhancement of a proposed location framework for securing critical infrastructures using context-aware self-defending objects. The proposed enhanced framework helps to negate the security vulnerabilities introduced through the use of general-purpose computer systems in critical infrastructures.

Location information is used to provide a diverse range of services to users such as emergency, navigation, billing, security, information and advertising services. This information is derived from a broad range of indoor and outdoor technologies. The location information thus derived is of different granularity, different co-ordination system and is controlled by numerous service providers. In addition to this, broad selections of devices are used for providing these services. Having a diverse range of applications requiring location information at different levels of granularity, the need to export location information across multiple devices and the existence of different location determination technologies necessitates the need for heterogeneous location network. These networks derive location information from multiple sources and provides various location-based services to users irrespective of the medium, device or technology used. Security, user privacy and management of location information are some of the important issues that need to be addressed. The main contribution of this thesis is the design of a secure and privacy assured heterogeneous location architecture. A formal methodology was chosen to design the heterogeneous location architecture. The design of the architecture resulted in a novel key distribution protocol and a model for information flow that can be easily encapsulated into applications or architectures having similar requirements. The research also resulted in the enhancement of a proposed location framework for securing critical infrastructures using context-aware self-defending objects. The proposed enhanced framework helps to negate the security vulnerabilities introduced through the use of general-purpose computer systems in critical infrastructures.

Exploiting context-aware environments, where sensors scattered in a environment update presence servers to indicate the environmental changes can be used to enable new services. Such systems have become feasible both in terms of technical di±culties and their cost. A current focus in this area of research is how a context-aware system should be designed so that it reduces both the cost and complexity of the infrastructure, but still provides the desired services. One of the key components of many context-aware systems is location sensing, because a user's location is one of the most used elements of information in context-aware services. In this paper, we address cost e®ective location services by utilizing measurements of WLAN signal strength. We derive from these measurements an estimate of a device's location, and make this location information available via a SIP Presence User Agent, thus making location information readily available to services that might wish to use this information - while hiding details of how this information is acquired from these services.
Genom att utnyttja kontextmedvetna miljöer, där sensorer i en miljö uppdaterar närvarande servrar med information omändringar i omgivningen, så kan man öppna upp vägar för nya tjänster. Sådana system har blivit utförbara bade när det gäller tekniska svarigheter och deras kostnader. Inom forskning som rör sådana här system ägnas mycket uppmärksamhetåt hur en kontextmedveten miljö borde designas för att minimera både kostnaden och komplexiteten av infrastrukturen, men fortfarande tillhandahålla den önskade tjänsten. En av huvudkomponenterna i många kontextmedvetna system är platsuppfattning, eftersom en användares position är en av de mest använda elementen av information i kontextmedvetna tjänster. I den här uppsatsen ägnar vi oss åt kostnadseffektiva platstjänster genom att mäta signalstyrkan av ett WLAN. Genom dessa mätningar uppskattar vi en enhets position och gör denna information tillgänglig via en SIP Presence User Agent, och gör på så vis platsinformationen tillgänglig för tjänster som kan vilja ha den { utan att avslöja detaljer om hur informationen har skaffats.

Thesis (Ph.D.)--Computing, Georgia Institute of Technology, 2009.
Committee Chair: Abowd, Gregory; Committee Member: Edwards, Keith; Committee Member: Grinter, Rebecca; Committee Member: LaMarca, Anthony; Committee Member: Starner, Thad.

This thesis describes research on methods for Ubiquitous/Pervasive Computing to better suit users in an Intelligent Environment. The approach is to create and equip a computing environment, such as our Active Office, with technologies that can identify user needs and meet these need in a timely, efficient and unobtrusive manner.¶ The critical issues in the Intelligent Environment are how to enable transparent, distributed computing to allow continued operation across changing circumstances and how to exploit the changing environment so that it is aware of the context of user location, the collection of nearby people and objects, accessible devices and changes to those objects over time.¶ Since the Intelligent Environment is an environment with rapid and rich computing processing, the distributed context processing architecture (DiCPA) was developed to manage and respond to rapidly changing aggregation of sensor data. This architecture is a scalable distributed context processing architecture that provides: 1. continued operation across changing circumstances for users, 2. the collection of nearby people and objects, 3. accessible devices and 4. the changes to those objects over time in the environment. The DiCPA approach focuses on how the Intelligent Environment provides context information for user location, user mobility and the user activity model. Users are assumed mobile within the Intelligent Environment and can rapidly change their access to relevant information and the availability of communications and computational resources.¶ Context-Aware Computing is a new approach in software engineering for Intelligent Environment. It is an approach in the design and construction of a context-aware application that exploits rapid changes in access to relevant information and the availability of communication and computing resources in the mobile computing environment. The goal of Context-Aware Computing is to make user interaction with the computer easier in the smart environment where technology is spread throughout (pervasive), computers are everywhere at the same time (ubiquitous) and technology is embedded (ambient) in the environment. Context-aware applications need not be difficult, tedious or require the acquisition of new skills on the part of the user. They should be safe, easy, simple to use and should enable new functionality without the need to learn new technology. They should provide relevant information and a simple way for a user to manage.¶ The Intelligent Environment requires a context-aware application to improve its efficiency and to increase productivity and enjoyment for the user. The context awareness mechanism has four fundamental cores i.e. identity (who), activity (what), location (where) and timestamp (when). Based on DiCPA architecture, the model of user location (where), user mobility (where), user activity (what) and Intelligent Environment response (what) were developed. Prototypes were also developed to proof the Context-Aware Computing concept in the Intelligent Environment.¶ An Intelligent Environment uses the multi-disciplinary area of Context-Aware Computing, which combines technology, computer systems, models and reasoning, social aspects, and user support. A “good quality” project for Context-Aware Computing requires core content and provides iterative evaluation processes, which has two types of iteration: design and product iteration of the evaluation. The aim of the development of an evaluation program in Context-Aware Computing is to determine what to test, how to test and the appropriate metrics to use. This work presents the metrics for a good quality project in the Context-Aware Computing area, which is followed by the evaluation of the prototypes of this work.

The modern organizations are becoming increasingly dependent on Information Technology (IT), which requires implementation of an effective management support on this area where the high investments achieved can add value for the companies. The intent of reducing the damage caused by unusual computer problems is to provide an active and complete technical assistance to the users. This support team, which is responsible for IT maintenance, was initially named help desk and later, it was modified to service desk due to its significance and the integrated services that were added in this work area. The high diversity of hardware and software besides the current user s demand, which increase the complexity of the technical assistance, creates a new request: the human resource allocation that provides an appropriate profile for solving different types of computers problems. Professionals, who don t have the proper expertise (work experience and practice) for specific maintenance, can bring unnecessary travel for the technician and work inactivity for the requester.This paper aims the adjustment of a service desk tool developed at the Federal University of Santa Maria. The remodelling involves a context-aware computing, location awareness and temporal context characteristics and the technician expertise. The main results demonstrate a service desk context-aware system (sdvpc-SC), that also enables its access through a mobile device and the improvement of technical calls distributed by expertise and geographical location. The tests proved that the system is technically possible and its adjustments can be easily implemented in different types systems of the same category.
As organizações modernas estão se tornando cada vez mais dependentes da Tecnologia da Informação (TI), o que torna imprescindível a implementação de um gerenciamento efetivo da TI para que os altos investimentos realizados no setor possam agregar valor às empresas. Quando surge um problema em algum equipamento de informática, ocasionando um funcionamento anormal dos serviços, espera-se que o usuário tenha uma resposta rápida e clara da equipe de suporte para minimizar os prejuízos causados. Esta equipe de suporte, responsável por resolver os problemas de TI, foi inicialmente denominada help desk, mas devido a sua importância e a novos serviços agregados a sua área de atuação passou a ser chamada de service desk. A grande diversidade de hardware e software aliada as atuais exigências dos usuários torna o atendimento mais complexo e cria uma nova demanda: a alocação de recursos humanos que apresentem o perfil adequado para resolução dos diferentes tipos de problemas. Alocar técnicos que não possuem a expertise (experiência e prática) correta para a solução do problema pode ocasionar, para o técnico, a perda de tempo pelo deslocamento desnecessário, e para o usuário a ociosidade devido à falta de solução do incidente no primeiro atendimento. Este trabalho apresenta a adaptação de uma ferramenta de service desk desenvolvida na Universidade Federal de Santa Maria. As adequações envolvem características da computação sensível ao contexto de localização, temporal e de expertise do técnico. Como principais resultados, obteve-se um sistema de service desk sensível ao contexto (sdvpc-SC), que possibilita o seu acesso através de dispositivo móvel, com a otimização das chamadas por expertise e a localização geográfica do técnico. Os testes demonstraram que o sistema é tecnicamente viável e as adaptações realizadas neste trabalho podem ser facilmente implementadas em diferentes tipos de sistemas da mesma categoria.

This work describes a design of a multimedia content delivery system based on context, to provide multimedia information and other services according to the user location and his preferences. It focuses on mobility and the problem of different coherent and cohesive presentations depending on the available resources of the presentation environment.

Les systèmes d'information mobiles et ambiants liés à la localisation et à la navigation évoluent progressivement vers des environnements à petite échelle. La nouvelle frontière scientifique et technologique concernent les applications qui assistent les utilisateurs dans leurs déplacements et activités au sein d'espaces bâtis dits "indoor" (e.g., aéroports, musées, bâtiments). La recherche présentée par cette thèse développe une représentation de données spatiales d'un environnement "indoor" qui tient compte des dimensions contextuelles centrées sur l'utilisateur et aborde les enjeux de gestion de données mobiles. Un modèle de données "indoor" hiérarchique et sensible au contexte est proposé. Ce modèle intègre différentes dimensions du contexte en plus de la localisation des entités concernées, telles que le temps et les profils des utilisateurs. Ce modèle est basé sur une structure arborescente dans laquelle l'information spatiale est représentée à différents niveaux d'abstraction. Cette conception hiérarchique favorise un traitement adaptatif et efficace des Requêtes Dépendantes de la Localisation (RDL) qui sont considérées comme des éléments clés pour le développement des différentes catégories de services de géolocalisation sensibles au contexte. Un langage de requêtes continues est développé et illustré par des exemples de requêtes RDL. Ce langage exploite le concept des granules spatiaux, et permet de représenter les requêtes continues et dépendantes de la localisation en prenant compte des préférences de l'utilisateur au moment de l'exécution. Cette approche de modélisation est complétée par le développement d'une architecture générique pour le traitement continu des requêtes RDL et par la conception et la mise en œuvre de plusieurs algorithmes qui permettent un traitement efficace des requêtes dépendantes de la localisation sur des objets mobiles en "indoor". Plusieurs algorithmes de traitement continu des requêtes de recherche de chemin hiérarchique et des requêtes de zone appliquées à des objets statiques et/ou en mouvement sont présentés. Ces algorithmes utilisent une approche hiérarchique et incrémentale afin d'exécuter efficacement les requêtes RDL continues. Un prototype encapsulant le modèle de données hiérarchique, les opérateurs et les contraintes introduits dans le langage de requête ainsi que les différents algorithmes et méthodes pour la manipulation de requêtes RDL a été développé comme une extension du SGBD Open Source PostgreSQL. Une étude expérimentale des solutions développées a été menée pour étudier la performance et le passage à l'échelle à l'égard des propriétés intrinsèques des solutions proposées.

For many applications of location-based services, such as friend finding, buddy tracking,information sharing and cooperative caching in ad hoc networks, it is often important to be able to identify whether the positions of a given set of moving objects are within close proximity. To compute these kinds of proximity relations among large populations of moving objects, continuously available location position information of these objects must be correlated against each other to identify whether a given set of objects are in the specified proximity relation. In this dissertation, we state this problem, referring to it as the location constraint matching problem, both in the Euclidean space and the road network space. In the Euclidean space, we present an adaptive solution to this problem for various environments. We also study the position uncertainty associated with the constraint matching. For the road network space, where the object can only move along the edges of the road network, we propose an efficient algorithm based on graph partitioning, which dramatically restricts the search space and enhances performance. Our approaches reduce the constraint processing time by 80% for Euclidean space and by 90% for road network space respectively. The logical combination of individual constraints with conjunction, disjunction and negation results in more expressive constraint expressions than are possible based on single constraints. We model constraint expressions with Binary Decision Diagrams (BDD). Furthermore, we exploit the shared execution of constraint combinations based on the BDD modeling. All the algorithms for various aspects of the constraint processing are integrated in the research prototype L-ToPSS (Location-based Toronto Publish/Subscribe System). Through experimental study and the development of an analytical model, we show that the proposed solution scales to large numbers of constraints and large numbers of moving objects.

Yu Sheung Fan.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2003.
Includes bibliographical references (leaves 96-99).
Abstracts in English and Chinese.
Chapter 1. --- Introduction --- p.1
Chapter 1.1 --- Background: Context-Aware Applications --- p.2
Chapter 1.1.1 --- Definitions of Context --- p.2
Chapter 1.1.2 --- Existing Applications --- p.3
Chapter 1.1.3 --- Review --- p.6
Chapter 1.2 --- Research Motivation --- p.6
Chapter 1.3 --- Research Contributions --- p.8
Chapter 1.4 --- Thesis Outline --- p.8
Chapter 2. --- Location-sensing Technologies --- p.9
Chapter 2.1 --- Global Positioning System (GPS) --- p.9
Chapter 2.2 --- Existing indoor Location-sensing Systems --- p.11
Chapter 2.2.1 --- Active Badge --- p.11
Chapter 2.2.2 --- The Bat System --- p.12
Chapter 2.2.3 --- RADAR --- p.13
Chapter 2.2.4 --- PinPoint 3D-iD --- p.14
Chapter 2.2.5 --- Easy Living --- p.15
Chapter 2.3 --- System Properties and Risks --- p.16
Chapter 2.3.1 --- Accuracy --- p.17
Chapter 2.3.2 --- Cost --- p.18
Chapter 2.3.3 --- User Privacy --- p.18
Chapter 2.3.4 --- Location Representation --- p.19
Chapter 2.3.5 --- Other Limitations --- p.20
Chapter 2.4 --- Design Goals --- p.20
Chapter 2.4.1 --- Operate Inside Buildings --- p.21
Chapter 2.4.2 --- Preserve User Privacy --- p.21
Chapter 2.4.3 --- Low Cost --- p.22
Chapter 2.4.4 --- Fast Response --- p.22
Chapter 2.4.5 --- Spatial Recognition --- p.23
Chapter 2.4.6 --- Easy Administration and Deployment --- p.23
Chapter 2.5 --- Summary --- p.23
Chapter 3. --- System Design --- p.25
Chapter 3.1 --- System Architecture --- p.25
Chapter 3.2 --- Position-sensing Platform --- p.28
Chapter 3.2.1 --- Platform Architecture --- p.29
Chapter 3.2.2 --- Transmission Format --- p.30
Chapter 3.2.3 --- Distance Measurement --- p.31
Chapter 3.2.4 --- Position Estimation --- p.32
Chapter 3.2.5 --- Noise Cancellation --- p.35
Chapter 3.2.6 --- Location Inference --- p.36
Chapter 3.3 --- Summary --- p.38
Chapter 4. --- System Implementation --- p.39
Chapter 4.1 --- Communication Technologies --- p.39
Chapter 4.1.1 --- Ultrasound --- p.40
Chapter 4.1.2 --- Radio Frequency Identification (RFID) --- p.40
Chapter 4.1.3 --- Infrared Data Association (IrDA) --- p.41
Chapter 4.1.4 --- Bluetooth --- p.42
Chapter 4.2 --- Technologies Overview --- p.43
Chapter 4.2.1 --- Positioning --- p.44
Chapter 4.2.2 --- Networking --- p.44
Chapter 4.2.3 --- Communication Protocol --- p.45
Chapter 4.2.4 --- Range --- p.45
Chapter 4.2.5 --- Angle Dependency --- p.45
Chapter 4.2.6 --- Hardware supports --- p.46
Chapter 4.3 --- Hardware --- p.46
Chapter 4.3.1 --- Mobile Receiver --- p.46
Chapter 4.3.2 --- Transmitter --- p.47
Chapter 4.4 --- Software --- p.47
Chapter 4.4.1 --- Communication Protocol --- p.48
Chapter 4.4.2 --- Programming Environment --- p.48
Chapter 4.4.3 --- Signal Generation Routine --- p.48
Chapter 4.4.4 --- Position Estimation Routine --- p.50
Chapter 4.5 --- Summary --- p.53
Chapter 5. --- Evaluation --- p.55
Chapter 5.1 --- Platform Calibration --- p.55
Chapter 5.1.1 --- Outliers Elimination --- p.56
Chapter 5.1.2 --- Delay Determination --- p.58
Chapter 5.1.3 --- Window Size Determination --- p.61
Chapter 5.1.4 --- Revised Position Estimation Algorithm --- p.63
Chapter 5.2 --- Platform Evaluation - IrDA Figure 5.9: Experimental setup for distance performance evaluation --- p.64
Chapter 5.2.1 --- Distance Measurement Figure 5.10: IrDA horizontal distance measurement experiment results --- p.66
Chapter 5.2.2 --- Position Estimation - Static --- p.66
Chapter 5.2.3 --- Position Estimation - Mobile --- p.68
Chapter 5.3 --- Platform Evaluation - Bluetooth --- p.69
Chapter 5.3.1 --- Distance Measurement --- p.69
Chapter 5.3.2 --- Position Estimation - Static --- p.70
Chapter 5.3.3 --- Position Estimation ´ؤ Mobile --- p.71
Chapter 5.4 --- Summary --- p.73
Chapter 6. --- Applications --- p.74
Chapter 6.1 --- Potential Applications --- p.74
Chapter 6.1.1 --- Resource Tracking Systems --- p.75
Chapter 6.1.2 --- Shopping Assistance System --- p.76
Chapter 6.1.3 --- Doctor Tracking System --- p.77
Chapter 6.1.4 --- Tourist Guide Application --- p.78
Chapter 6.1.5 --- Other Applications --- p.79
Chapter 6.2 --- System Limitations --- p.79
Chapter 6.3 --- Summary --- p.79
Chapter 7. --- Conclusion --- p.80
Chapter 7.1 --- Summary --- p.80
Chapter 7.2 --- Future Work --- p.81
Chapter Appendix A: --- IrDA --- p.86
Chapter A.1 --- IrDA Physical Layer --- p.86
Chapter A.2 --- Physical Aspects of IrDA Physical Layer --- p.87
Chapter A.3 --- Discovering Other IrDA Devices --- p.88
Chapter A.4 --- Connection of IrDA Devices --- p.89
Chapter Appendix B: --- Bluetooth --- p.91
Chapter B.1 --- Bluetooth Stack --- p.91
Chapter B.2 --- Radio --- p.92
Chapter B.3 --- Frequency Hopping --- p.92
Chapter B.4 --- Package Structure --- p.92
Chapter B.5 --- The Link Controller --- p.93
Chapter B.6 --- The Link Manager --- p.93
Chapter B.7 --- Logical Link Control and Adaptation Protocol --- p.94
Chapter B.8 --- The Service Discovery Protocol --- p.94
Chapter B.9 --- Encryption and Security --- p.95
Bibliography --- p.96

We present a low cost and easily deployed infrastructure for location aware computing that is built using standard Bluetooth® technologies and personal computers. Mobile devices are able to determine their location to room-level granularity with existing bluetooth technology, and to even greater resolution with the use of the recently adopted bluetooth 1.2 specification, all while maintaining complete anonymity. Various techniques for improving the speed and resolution of the system are described, along with their tradeoffs in privacy. The system is trivial to implement on a large scale – our network covering 5,000 square meters was deployed by a single student over the course of a few days at a cost of less than US$1,000.
Singapore-MIT Alliance (SMA)

碩士
大葉大學
資訊管理學系碩士班
91
In the past serval years, mobile devices with wireless communication and location awareness capabilities have become increasingly popular. These advanced mobile devices together with their offering services create a new paradigm for mobile computing. People are able to access information on the Internet or get the location based services anytime and anywhere easily. However, the limited battery lifetime is one of the major issues limiting the usefulness of mobile devices. The more services mobile devices offer, the more power they need. Therefore, it is essential to have a power management software which can extend the battery lifetime effectively and efficeiently on mobile devices. 　This research integrates location information and power information to build a generic power management framework for location aware mobile computing. The proposed framework is modular, reusabile and extensible. Thus, it enables application developers to develop location aware application with power conservative for different mobile operating system rapidly and effectively. A simple location aware application based on the proposed framework is designed and implemented as a proof-of-concept example of this research.

No
Continuously identifying a user’s location context provides new opportunities to understand daily life and human behavior. Indoor location systems have been mainly based on WiFi infrastructures which consume a great deal of energy mostly due to keeping the user’s WiFi device connected to the infrastructure and network communication, limiting the overall time when a user can be tracked. Particularly such tracking systems on battery-limited mobile devices must be energy-efficient to limit the impact on the experience of using a phone. Recently, there have been a lot of studies of energy-efficient positioning systems, but these have focused on outdoor positioning technologies. In this paper, we propose a novel indoor tracking framework that intelligently determines the location sampling rate and the frequency of network communication, to optimize the accuracy of the location data while being energy-efficient at the same time. This framework leverages an accelerometer, widely available on everyday smartphones, to reduce the duty cycle and the network communication frequency when a tracked user is moving slowly or not at all. Our framework can work for 14 h without charging, supporting applications that require this location information without affecting user experience.

This thesis describes research on methods for Ubiquitous/Pervasive Computing to better suit users in an Intelligent Environment. The approach is to create and equip a computing environment, such as our Active Office, with technologies that can identify user needs and meet these need in a timely, efficient and unobtrusive manner.¶ The critical issues in the Intelligent Environment are how to enable transparent, distributed computing to allow continued operation across changing circumstances and how to exploit the changing environment so that it is aware of the context of user location, the collection of nearby people and objects, accessible devices and changes to those objects over time.¶ Since the Intelligent Environment is an environment with rapid and rich computing processing, the distributed context processing architecture (DiCPA) was developed to manage and respond to rapidly changing aggregation of sensor data. This architecture is a scalable distributed context processing architecture that provides: 1. continued operation across changing circumstances for users, 2. the collection of nearby people and objects, 3. accessible devices and 4. the changes to those objects over time in the environment. The DiCPA approach focuses on how the Intelligent Environment provides context information for user location, user mobility and the user activity model. Users are assumed mobile within the Intelligent Environment and can rapidly change their access to relevant information and the availability of communications and computational resources.¶ Context-Aware Computing is a new approach in software engineering for Intelligent Environment. ...