Context-awareness in pervasive computing environments can reduce user interactions with computing devices by making applications adaptive and autonomous. Context-aware applications rely on information about user context and user preferences to guide their own behaviour. However, context-aware applications do not always behave as users expect due to imperfection of context information, incorrect user preferences or incorrect adaptation rules. This may cause users to feel loss of control over their applications. To mitigate these problems, context-aware systems must provide mechanisms to strike a suitable balance between user control and software autonomy. Allowing users to scrutinise the system and allowing the system to sometimes include users in the adaptation decision making, can provide a balance of user control. This thesis addresses the shortcoming in development of context-aware pervasive systems with regard to providing balance between user control and software autonomy. The thesis shows that rather than making a context-aware application a complete black box, it is possible to allow user control of application adaptations. The system can reveal to the user what context information the system uses and how it arrives at adaptation decisions if the user requests such information. The user may decide to alter the adaptive behaviour of the system to achieve desired outcomes. Hence, a context-aware application becomes a closed loop system where the user is put into the loop if requested. The proposed approach is developed under an assumption that users differ in the level of their technology expertise and therefore the system has to provide explanations that are suitable for a particular level of user expertise. The thesis makes two important research contributions: design of the architectural framework and development of the platform exposing autonomic behaviour of context-aware applications. The architectural framework supports developers of context aware-applications in providing balance of control between users and software autonomy. The framework describes a set of models that allow revealing the adaptation behaviour of context-aware applications in a way suitable for users with various levels of expertise. The framework consists of: (i) a model for exposing elements that influence the context-aware behaviour, (ii) a generic architecture for providing balance of control, (iii) a user model, and (iv) a context graph based overview of context-aware adaptations. The platform exposing autonomic behaviour of context-aware applications is a proof of concept prototype of a software infrastructure (middleware) providing balance of control. The software infrastructure includes: (i) a Semantic Manager, developed to serve the description of elements required for explanations of the application behaviour; (ii) an extension of the PACE Middleware, to enable the middleware to expose the context information, preferences, adaptation rules and their evaluation traces, respectively. (iii) supporting tools for the application designer to prepare the overview of context-aware adaptations and review the evaluation traces. Finally, this thesis presents a case study that illustrates and evaluates the system supporting balance of control. This evaluation involves the existing application which is developed using the previous version of the PACE middleware. The case study validates the architectural framework and illustrates the process and issues involved in developing context-aware application that are able to expose elements that influence context-aware behaviour.

Abstract Context-awareness, a state where the device is aware of the situation in which it is used, is a technology which has gained an increasing amount of attention in recent years. A context-aware device can infer the use condition, and adapt its behavior according to the circumstances. Mobile handheld devices, which have been highly adopted by large user groups, especially in the form of mobile phones, constitute an interesting platform for context-awareness. They are used in different kinds of situations, where the preferences of users may vary, and where different features are prioritized. While the increasing complexity and growing number of features set challenges to intuitive and easy use of devices, context-awareness may offer solutions to more efficient use of mobile applications and services. This thesis investigates the interaction issues with context-aware mobile devices. The research has been exploratory including several separate case studies, where interaction and usability matters have been charted. These studies consider topics such as location-awareness, user-defined settings of context-aware applications, and information sharing and privacy. In addition to these case studies, the author has sough to draw a bigger picture on interaction and usability issues with context-aware mobile devices, and incorporated the findings to a more general framework. Through presenting the case studies it is concluded that context-awareness can improve the usability of mobile devices, but careful design in the application development phase must be emphasized. The usability risks identified through case studies relate to numerous themes, such as diminished user control, increased number of interruptions, information overflow, users' subjective understanding of context attributes and privacy threat. As context-aware technology employs greater risks, e.g. due to the uncertain nature of context recognition, the user-centric design practices and testing in the authentic environment of the context-aware applications should be stressed. The author proposes design guidelines, which have been developed based on the findings from distinct case studies. The design guidelines aim to offer tangible help to application designers, who may not be acquaint with the special characteristics of context-awareness, and intend to prevent potential usability problems identified through the individual studies. Moreover, an evaluation for the design guidelines and their iteration to the presented form is demonstrated.

This dissertation studies the context-aware application with its proposed algorithms at client side. The required context-aware infrastructure is discussed in depth to illustrate that such an infrastructure collects the mobile user’s context information, registers service providers, derives mobile user’s current context, distributes user context among context-aware applications, and provides tailored services. The approach proposed tries to strike a balance between the context server and mobile devices. The context acquisition is centralized at the server to ensure the usability of context information among mobile devices, while context reasoning remains at the application level. Hence, a centralized context acquisition and distributed context reasoning are viewed as a better solution overall. The context-aware search application is designed and implemented at the server side. A new algorithm is proposed to take into consideration the user context profiles. By promoting feedback on the dynamics of the system, any prior user selection is now saved for further analysis such that it may contribute to help the results of a subsequent search. On the basis of these developments at the server side, various solutions are consequently provided at the client side. A proxy software-based component is set up for the purpose of data collection. This research endorses the belief that the proxy at the client side should contain the context reasoning component. Implementation of such a component provides credence to this belief in that the context applications are able to derive the user context profiles. Furthermore, a context cache scheme is implemented to manage the cache on the client device in order to minimize processing requirements and other resources (bandwidth, CPU cycle, power). Java and MySQL platforms are used to implement the proposed architecture and to test scenarios derived from user’s daily activities. To meet the practical demands required of a testing environment without the impositions of a heavy cost for establishing such a comprehensive infrastructure, a software simulation using a free Yahoo search API is provided as a means to evaluate the effectiveness of the design approach in a most realistic way. The integration of Yahoo search engine into the context-aware architecture design proves how context aware application can meet user demands for tailored services and products in and around the user’s environment. The test results show that the overall design is highly effective,providing new features and enriching the mobile user’s experience through a broad scope of potential applications.

Cellular network based Machine-to-Machine (M2M) communications have been growing rapidly in recent years, being used in a wide range of services such as security, metering, health, remote control, tracking and so on. A critical issue that needs to be considered in M2M communications is the energy efficiency, typically the machines are powered by batteries of low capacity and it is important to optimize the way the power is consumed. In search of better M2M systems, we propose a context-aware framework for M2M communications so the machine type communication (MTC) devices dynamically adapt their settings depending on a series of characteristics such as data reporting mode and quality of service (QoS) features so higher energy efficient is achieved, extending the operating lifetime of the M2M network. Simulations were performed with four commonly used M2M applications:home security, telehealth, climate and smart metering, achieving considerable energy savings and operating lifetime extension on the network. Thus, it is shown that contexts play an important role on the energy efficiency of a M2M system.

Today almost everyone owns a mobile phone, adults along with teenagers and kids. Even laptops and other wearable devices such as personal digital assistants (PDA’s) are become more common. We want constant connectivity to networks and the Internet, which in turn makes us more and more available. Context-awareness will play a bigger role for these devices in the future. Aware of its surroundings, a portable device can adapt and communicate with different devices and objects, hiding complexity from the user. This enables a simpler user interface and reduces user interaction. This master thesis builds partially upon the prior work done by Maria José Parajón Dominguez. To realize the concept of “context-awareness” HP’s iPAQ Pocket PC h5500 was used together with a server/client application developed as part of this thesis project. Questions that were addressed; what are the effects on the traffic to and from the mobile device of having a personal voice interface; what are the effect on the traffic to and from the mobile device of having significant local storage; and is it possible to exchanging personal CODECs to reduce bandwidth. With this background in mind, this thesis focuses on audio for mobile users in a quest to create more useful devices by exploiting context awareness. / Idag äger nästan alla en mobiltelefon, vuxna, tonåringar så väl som barn. Även bärbara datorer och andra bärbara apparater så som ”personal digital assistans” (PDA:er) blir vanligare. Vi strävar efter konstant dataåtkomst, vilket i sin tur gör oss mer och mer tillgängliga för andra. ”Context-awareness” kommer att spela en större roll för dessa apparater i framtiden. Medveten om sin omgivning, så kan en portabel apparat anpassa sig och kommunicera med andra, utan att göra det komplext för användaren. Detta medför ett enklare gränssnitt för användaren och minskar användarens samspel. Detta examensarbete bygger delvis på ett tidigare arbete av Maria José Parajón Dominguez. För att realisera begreppet “context-awareness” användes HP:s iPAQ Pocket PC h5500 tillsammans med en utvecklad server/klient programvara. Frågor som man försökte besvara var; vilken effekt trafiken har till och från PDA:n vid användning av ett röstgränssnitt; vilken effekt trafiken har till och från PDA:n vid lagring av mycket lokalt utrymme; och om det är möjligt att utväxla personliga algoritmer, så kallade CODECs. Med detta i tanke, så försöker detta examensarbete att fokusera på ljud för mobila användare i ett försök att skapa mer användbara apparater genom att utnyttja ”context-awareness”.

Context-aware applications are applications that exploit knowledge of the situation of the user (i.e. the user’s context) to adapt their behavior, thus helping the user achieve his or her daily tasks. Today, the transfer of context information needs to take place over unreliable and dynamically changing networks. Moreover context information may be produced in different devices connected to different networks. These difficulties have limited the development of context-aware applications. This thesis presents a context distribution method exploiting the event notification mechanisms of the Session Initiation Protocol (SIP), aiming to provide access to context information regardless of where it is produced. The context distribution component presented in this thesis uses SIP for Instant Messaging and Presence Leveraging Extensions (SIMPLE) to enable context sharing by using a SIP presence server, specifically the SIP Express Router (SER) and its presence module. This context distribution component allows distribution of context information in both synchronous and asynchronous mode. The distribution mode depends on the application requirements for context distribution, as well as the nature and characteristics of the contextinformation. In this thesis, based on system scalability, the user’s mobility, and latency - recommendations are given about in which situations each mode is more suitable for distributing context information. The system was evaluated using a load generator. The evaluation revealed that the server is highly scalable. The response time for synchronous retrieval of context information is nearly constant, while in asynchronous mode the time to process a subscription increases with the amount of information in the database regarding previous subscriptions. Notifications are sent at a regular rate (≈2800 notifications per second); however there is a purposely random delay (0 to 1 second), between an update of context information (i.e. receipt of a publish message) and the start of notifications to subscribed users. The requirements of the context-aware applications using the distribution component, such as response time, have to be taken into account when deciding upon the mode of context distribution for each application. This thesis provides some empirical data to help an application developer make this selection. / Kontext-medvetna (eng. Context-aware) applikationer är applikationer som utnyttjar information om användarens situation (d.v.s. användarens kontext) och förändrar applikationens beteende i syfte att hjälpa användaren i dennes vardagliga arbetsuppgiften. Idag överförs kontextuell-information (eng. context information) i nätverk som är opålitliga och dynamiskt föränderliga. Därtill tillkommer komplexiteten att kontextuell-information är ibland producerad i olika noder anslutna till olika nätverk.Utvecklingen av kontext-medvetna applikationer har hittills begränsats av ovannämnda svårigheter. Denna avhandling presenterar en metod för att distribuera kontextuell-information genom användning av mekanismer för händelsemeddelande (eng. event notification mechanisms) inbyggda i Session Initiation Protocol (SIP). Målet är att undersöka hur metoden kan användas för att möjliggöra tillgång till kontextuell-information oavsett vart den är producerad. Komponenten för distribution av kontextuell data, som presenteras i denna uppsats, använder SIP för direktmeddelanden (eng. Instant Messaging) och tekniken “Presence Leveraging Extensions (SIMPLE)” för datadelning av kontextuell data (eng. Context sharing). För detta ändamål används SIP närvaroserver (eng. SIP presence server), mer specifikt modulen för närvaroinformation tillhörande SIP Expressroutrar (SER). Komponenten för distribution av kontextuell information möjliggör både synkront och asynkront distribution. Valet mellan de två beror delvist på applikationens kravspecifikation för distribution av kontextuell information, delvist på typen av den kontextuella informationen. Baserat på systemet skalbarhet (eng. Scalability), användarens rörlighet och latens (eng. latency) kan man ge rekommendationer vilken av de två distributionssätten, synkront eller asynkront, som är lämpligast för distributionen av kontextuell information. Systemet utvärderades med hjälp av ett program som genererar belastning (eng. load generator). Resultaten visar att systemet är mycket skalbart. Responstiden för synkront åtkomst av kontextuell information är nästan konstant, medan responstiden för asynkront åtkomst ökar med informationsmängden i databasen, i respekt till den föregående prenumerationen av kontextändringar. Händelsemeddelande skickas regelbundet ( 2800 meddelande per sekund). Vi har dock medvetet valt att skapa en slumpmässigt dröjsmål (0 till 1 sekund) mellan varje uppdatering av kontextuell information (t.ex. en kvitto på en Publish-meddelande) och den tidpunkten då händelsemeddelande skickas till de användare som prenumererar på ändringarna. För utvecklingen av varje kontext-medveten applikation, som distribuerar kontextuell information måste man ta hänsyn till responstid vid beslut huruvida man ska välja synkront eller asynkront sätt för distribution. Denna uppsats ger empirisk data som hjälper applikationsutvecklare i detta val.

This dissertation presents novel approaches to test context aware applications that suffer from a cost prohibitive number of context and GUI events and event combinations. The contributions of this work to test context aware applications under test include: (1) a real-world context events dataset from 82 Android users over a 30-day period, (2) applications of Markov models, Closed Sequential Pattern Mining (CloSPAN), Deep Neural Networks- Long Short Term Memory (LSTM) and Gated Recurrent Units (GRU), and Conditional Random Fields (CRF) applied to predict context patterns, (3) data driven test case generation techniques that insert events at the beginning of each test case in a round-robin manner, iterate through multiple context events at the beginning of each test case in a round-robin manner, and interleave real-world context event sequences and GUI events, and (4) systematically interleaving context with a combinatorial-based approach. The results of our empirical studies indicate (1) CRF outperforms other models thereby predicting context events with F1 score of about 60% for our dataset, (2) the ISFreqOne that iterates over context events at the beginning of each test case in a round-robin manner as well as interleaves real-world context event sequences and GUI events at an interval one achieves up to four times better code coverage than not including context, 0.06 times better coverage than RSContext that inserts random context events at the beginning of each test case, 0.05 times better coverage than ISContext that iterates over context events to insert at the beginning of each test case in a round-robin manner, and 0.04 times better coverage than ISFreqTwo that iterates over context events at the beginning of each test case in a round-robin manner as well as interleaves real-world context event sequences and GUI events at an interval two on an average across four subject applications and, (3) the PairwiseInterleaved technique that selects a different context event at the beginning of each test case by iterating through context covering array in a round-robin manner and systematically interleaves context with GUI events by prioritizing the execution of GUI events in new contexts achieves higher code coverage up to a factor of six when compared to Monkey, up to a factor of 1.3 when compared to a technique that generates test suites without context events, and similar code coverage when compared to ISContext that iterates over context events to insert at the beginning of each test case in a round-robin manner on an average across five subject applications.

Our hunger for data has grown tremendously over the years which has led to a demand for the increase in the available radio spectrum for communications. The Federal Communications Commission in the United States allowed for the sharing of the CBRS band (3550-3700 MHz) a few years ago. Since then, research has been done by both industry and academia to identify similar opportunities in other radio bands as well. This research is, however, being hampered due to a lack of experimental frameworks where the various aspects of spectrum sharing can be studied. To this end, we propose to develop an open-source spectrum access system that incorporates context awareness and multi-band operational support and serves as an RandD tool for the research community. We have developed a novel Prioritization Framework that takes the current operational context of each user into account to determine their relative priority, within or outside their user class/group, for transmission in the network. We also introduce a Policy Engine for the configuration and management of dynamic policies (or rules) for defining the relationships between the various forms of context information and their relative impact on a user's overall priority. We have performed several experiments to show how context awareness impacts the spectrum sharing efficiency and quality of service. Due to its modular and extensible nature, we expect that this tool will be used by researchers and policy-makers to implement their own policies and algorithms and test their efficacy in a simulated radio environment. / Master of Science / Over the years, the advancements in the internet and communication technology have made us more and more data-hungry. Consequently, the electromagnetic spectrum on which data is transmitted has become a sparse resource. Governments worldwide are working together with academia and industry to find the most efficient utilization of this resource. If the current users of protected spectrum could share their bands with other licensed or opportunistic users, then a tremendous amount of spectrum could be freed up for public and private use. To facilitate rapid research and development in this field, this thesis proposes the development of an open-source, modular, and extensible Context-Aware Dynamic Spectrum Access System. In this system, we explore the usage of several traditional and novel context information in spectrum allocation, which in turn helps us improve the efficiency and resiliency of spectrum management while ensuring that incumbent users are not adversely affected by other licensed or unlicensed users. We develop cognitive modules for context-based prioritization of users for allocation through a novel Prioritization Framework and for enabling the use of dynamic policies or rules (governing spectrum allocation) instead of static policies that most systems use today. We simulate several operational scenarios and depict our tool's performance in them. Through our experiments and discussions, we highlight the significance of this tool for researchers, policy-makers, and regulators for studying spectrum sharing in general, and context-aware, dynamic policy-based spectrum sharing in particular.

Technological advancements in sensor miniaturization, processing power and faster networks has broadened the scope of our contemporary compute-infrastructure to an extent that Context-Aware Intelligent Environment (CAIE)--physical spaces with computing systems embedded in it--are increasingly commonplace. With the widespread adoption of intelligent personal agents proliferating as close to us as our living rooms, there is a need to rethink the human-computer interface to accommodate some of their inherent properties such as multiple focus of interaction with a dynamic set of devices and limitations such as lack of a continuous coherent medium of interaction. A CAIE provides context-aware services to aid in achieving user's goals by inferring their instantaneous context. However, often due to lack of complete understanding of a user's context and goals, these services may be inappropriate or at times even pose hindrance in achieving user's goals. Determining service appropriateness is a critical step in implementing a reliable and robust CAIE. Explicitly querying the user to gather such feedback comes at the cost of user's cognitive resources in addition to defeating the purpose of designing a CAIE to provide automated services. The CAIE may, however, infer this appropriateness implicitly from the user, by observing and sensing various behavioral cues and affective reactions from the user, thereby seamlessly gathering such user-feedback. In this dissertation, we have studied the design space for incorporating user's affective reactions to the intelligent services, as a mode of implicit communication between the user and the CAIE. As a result, we have introduced a framework named CAfFEINE, acronym for Context-aware Affective Feedback in Engineering Intelligent Naturalistic Environments. The CAfFEINE framework encompasses models, methods and algorithms establishing the validity of the idea of using a physiological-signal based affective feedback loop in conveying service appropriateness in a CAIE. In doing so, we have identified methods of learning ground-truth about an individual user's affective reactions as well as introducing a novel algorithm of estimating a physiological signal based quality-metric for our inferences. To evaluate the models and methods presented in the CAfFEINE framework, we have designed a set of experiments in laboratory-mockups and virtual-reality setup, providing context aware services to the users, while collecting their physiological signals from wearable sensors. Our results provide empirical validation for our CAfFEINE framework, as well as point towards certain guidelines for conducting future research extending this novel idea. Overall, this dissertation contributes by highlighting the symbiotic nature of the subfields of Affective Computing and Context-aware Computing and by identifying models, proposing methods and designing algorithms that may help accentuate this relationship making future intelligent environments more human-centric. / Ph. D. / Physical spaces containing intelligent computing agents have become an increasingly commonplace concept. These systems when populating a physical space, provides intelligent services by inferring user’s immediate needs, they are called intelligent environments. With this widespread adoption of intelligent systems, there is a need to design computer interfaces that focuses on the human user’s responses. In order for this service-delivery interaction to feel natural, these interfaces need to sense a user’s disapproval of a wrong service, without the user actively indicating so. It is imperative that implicitly inferring a user’s disapproval of a service by observing and sensing various behavioral cues from the user, will help in making the computing system cognitively disappear into the background. In this dissertation, we have studied the design space for incorporating user’s affective reactions to the intelligent services, as a mode of implicit communication between the user and the intelligent system. As a result, we have introduced an interaction framework named CAfFEINE, acronym for Context-aware Affective Feedback in Engineering Intelligent Naturalistic Environments. The CAfFEINE framework encompasses models, methods and algorithms exploring the validity of the idea of using physiological signal based affective feedback in intelligent environments. To evaluate the models and algorithms, we have designed a set of experimental protocols and conducted user studies in virtual-reality setup. The results from these user studies demonstrate the feasibility of this novel idea, in addition to proposing new methods of evaluating the quality of underlying physiological signals. Overall, this dissertation contributes by highlighting the symbiotic nature of the subfields of Affective Computing and Context-aware Computing and by identifying models, proposing methods and designing algorithms that may help accentuate this relationship making future intelligent environments more human-centric.

Σε αυτή τη διδακτορική διατριβή μελετήσαμε τις δυνατότητες αξιοποίησης των οντολογιών στην αναπαράσταση γνώσης σε συστήματα απανταχού και κινητού υπολογίζειν. / In this thesis we studied the use of ontologies for knowledge representation in ubiquitous and mobile computing.