Location Context in Mobile and Pervasive Computing Systems: Technologies, Architectures & Implementation

Technological advances allow manufacturing of smaller and more portable, yet increasingly powerful computing devices, which are equipped with wireless communicating capabilities. The integration of information processing into wirelessly interconnected everyday objects is the primary goal of pervasive computing. A pragmatic variant of the pervasive computing paradigm has been described by IBM chairman Lou Gerstner: a billion people interacting with a million e-businesses through a trillion interconnected intelligent devices. Persons move around, and therefore it is important for such a scenario to operate so that e-businesses and the interconnected devices know where they are and what other objects are in their vicinity. Location information seems crucial information for e-businesses and services. The pervasive environment is strongly interconnected, and the participants profit from this fact by detecting their surroundings and offering proactive service to objects in their vicinity. This work examines the location context in mobile and pervasive computing systems. Thereby, it investigates the impact of mobile and pervasive computing on location-based systems, and especially concentrates on proactive services, i.e., services that act on behalf of the user. To begin, the thesis probes standard locating algorithms and determines their applicability for proactive services. Then, it proposes adaptations to these algorithms through a novel mapping between locations and objects (formalizing the difference between locating and location systems). Next, it presents the proof-of-concept implementation (called Mobile Shadow) in detail to support the claims made in the first part. It starts with presenting the computation and data model for Mobile Shadow. Then, it shows by simulation that the model is sound and that the adaptations are valid and improve the overall quality of service. Finally, it presents implementation details such as the location system and how to create a new service. After presenting the proof-of-concept implementation, this thesis evaluates in detail the software architectures of Mobile Shadow and two more architecture prototypes suitable for location-based systems. Based on this evaluation and the discussion, and the thesis concludes with presenting a set of guidelines for choosing between these three architecture prototypes for developing a location-based system.