Context reasoning, context prediction and proactive adaptation in pervasive computing systems

Sammanfattning: The paradigm of pervasive computing aims to integrate the computing technologies in a graceful and transparent manner, and make computing solutions available anywhere and at any time. Different aspects of pervasive computing, like smart homes, smart offices, social networks, micromarketing applications, PDAs, etc. are becoming a part of everyday life. Context of pervasive computing system is any piece of information that can be of possible interest to the system. Context often includes location, time, activity, surroundings, etc. One of the core features of pervasive computing systems is context awareness – the ability to use context information to the benefit of the system. The thesis proposes a set of context prediction and situation prediction methods on top of enhanced situation awareness mechanisms. Being aware of the future context enables a pervasive computing system to choose the most efficient strategies to achieve its stated objectives and therefore a timely response to the upcoming situation can be provided. This thesis focuses on the challenges of context prediction, but in order to become really efficient and useful, context prediction approaches need to be gracefully integrated with different other aspects of reasoning about the context. This thesis proposes a novel integrated approach for proactively working with context information. In order to become efficient, context prediction should be complemented with proper acting on predicted context, i.e. proactive adaptation. The majority of current approaches to proactive adaptation solves context prediction and proactive adaptation problems in sequence. This thesis identifies the shortcomings of that approach, and proposes an alternative solution based on reinforcement learning techniques. The concept of situation provides useful generalization of context data and allows eliciting the most important information from the context. The thesis proposes, justifies and evaluates improved situation modeling methods that allow covering broader range of real-life situations of interest and efficiently reason about situation relationships. The context model defines the pervasive computing system’s understanding of its internal and external environments, and determines the input for context prediction solutions. This thesis proposes novel methods for formal verification of context and situation models that can help to build more reliable and dependable pervasive computing systems and avoid the inconsistent context awareness, situation awareness and context prediction results. The architecture of pervasive computing system integrates all the aspects of context reasoning and governs the interaction and collaboration between different context processing mechanisms. This thesis proposes, justifies and evaluates the architectural support for context prediction methods. The novel architectural solutions allow encapsulating various practical issues and challenges of pervasive computing systems and handling them on low levels of context processing, therefore, supporting the efforts for efficient context prediction and proactive adaptation.