Showing papers on "Context awareness published in 2003"

CARISMA: context-aware reflective middleware system for mobile applications

Abstract: Mobile devices, such as mobile phones and personal digital assistants, have gained wide-spread popularity. These devices will increasingly be networked, thus enabling the construction of distributed applications that have to adapt to changes in context, such as variations in network bandwidth, battery power, connectivity, reachability of services and hosts, etc. In this paper, we describe CARISMA, a mobile computing middleware which exploits the principle of reflection to enhance the construction of adaptive and context-aware mobile applications. The middleware provides software engineers with primitives to describe how context changes should be handled using policies. These policies may conflict. We classify the different types of conflicts that may arise in mobile computing and argue that conflicts cannot be resolved statically at the time applications are designed, but, rather, need to be resolved at execution time. We demonstrate a method by which policy conflicts can be handled; this method uses a microeconomic approach that relies on a particular type of sealed-bid auction. We describe how this method is implemented in the CARISMA middleware architecture and sketch a distributed context-aware application for mobile devices to illustrate how the method works in practice. We show, by way of a systematic performance evaluation, that conflict resolution does not imply undue overheads, before comparing our research to related work and concluding the paper.

Managing context information in mobile devices

Abstract: We present a uniform mobile terminal software framework that provides systematic methods for acquiring and processing useful context information from a user's surroundings and giving it to applications. The framework simplifies the development of context-aware mobile applications by managing raw context information gained from multiple sources and enabling higher-level context abstractions.

Context-awareness on mobile devices - the hydrogen approach

Abstract: Information about the user's environment offers new opportunities and exposes new challenges in terms of time-aware, location-aware, device-aware and personalized applications. Such applications constantly need to monitor the environment - called context - to allow the application to react accordingly to this context. Context-awareness is especially interesting in mobile scenarios where the context of the application is highly dynamic and allows the application to deal with the constraints of mobile devices in terms of presentation and interaction abilities and communication restrictions. Current context-aware applications often realize sensing of context information in an ad hoc manner. The application programmer needs to deal with the supply of the context information including the sensing of the environment, its interpretation and its disposal for further processing in addition to the primary purpose of the application. The close interweavement of device specific context handling with the application obstructs its reuse with other hardware configurations. Recently, architectures providing support for context-aware applications have been developed. Up to now such architectures are not trimmed to the special requirements of mobile devices regarding particularly the limitations of network connections, limited computing power and the characteristics of mobile users. This paper proposes an architecture and a software framework - the hydrogen context framework -which support context-awareness for considering these constraints. It is extensible to consider all kind of context information and comprises a layered architecture. To prove the feasibility the framework has been implemented to run on mobile devices. A context-aware postbox is realized to demonstrate the capabilities of the framework.

An infrastructure for context-awareness based on first order logic

Abstract: Context simplifies and enriches human-human interaction. However, enhancing human-computer interaction through the use of context remains a difficult task. Applications in pervasive and mobile environments need to be context-aware so that they can adapt themselves to rapidly changing situations. One of the problems is that there is no common, reusable model for context used by these environments. In this paper, we propose a model of context that is based on first order predicate calculus. The first order model allows complex rules involving contexts to be written. It also enables automated inductive and deductive reasoning to be done on contextual information. The first order model allows an expressive description of context using Boolean operators and existential and universal quantifiers. Based on this model, an infrastructure to enable context-awareness in ubiquitous computing environments has been developed. The infrastructure allows the easy development and deployment of various sensors and context-aware applications. It also allows distributed reasoning to take place. This context infrastructure is part of our smart spaces framework for ubiquitous computing, Gaia.

Multi-sensor Activity Context Detection for Wearable Computing

Abstract: For wearable computing applications, human activity is a central part of the user’s context. In order to avoid user annoyance it should be acquired automatically using body-worn sensors. We propose to use multiple acceleration sensors that are distributed over the body, because they are lightweight, small and cheap. Furthermore activity can best be measured where it occurs. We present a hardware platform that we developed for the investigation of this issue and results as to where to place the sensors and how to extract the context information.

Lessons from the lighthouse: collaboration in a shared mixed reality system

Abstract: Museums attract increasing numbers of online visitors along with their conventional physical visitors. This paper presents a study of a mixed reality system that allows web, virtual reality and physical visitors to share a museum visit together in real time. Our system allows visitors to share their location and orientation, communicate over a voice channel, and jointly navigate around a shared information space. Results from a study of 34 users of the system show that visiting with the system was highly interactive and retained many of the attractions of a traditional shared exhibition visit. Specifically, users could navigate together, collaborate around objects and discuss exhibits. These findings have implications for non-museum settings, in particular how location awareness is a powerful resource for collaboration, and how 'hybrid objects' can support collaboration at-a-distance.

Cerberus: a context-aware security scheme for smart spaces

Abstract: Ubiquitous computing has fueled the idea of constructing sentient, information-rich "smart spaces" that extend the boundaries of traditional computing to encompass physical spaces, embedded devices, sensors, and other machinery. To achieve this, smart spaces need to capture situational information so that they can detect changes in context and adapt themselves accordingly. However, without considering basic security issues ubiquitous computing environments could be rife with vulnerabilities. Ubiquitous computing environments impose new requirements on security. Security services, like authentication and access control, have to be non-intrusive, intelligent, and able to adapt to the rapidly changing contexts of the spaces. We present a ubiquitous security mechanism that integrates context-awareness with automated reasoning to perform authentication and access control in ubiquitous computing environments.

Unsupervised, dynamic identification of physiological and activity context in wearable computing

Abstract: Context-aware computing describes the situationwhere a wearable / mobile computer is aware of itsuser's state and surroundings and modifies its behaviorbased on this information. We designed, implemented andevaluated a wearable system which can determine typicaluser context and context transition probabilities onlineand without external supervision. The system relies ontechniques from machine learning, statistical analysisand graph algorithms. It can be used for onlineclassification and prediction. Our results indicate thepower of our method to determine a meaningful usercontext model while only requiring data from acomfortable physiological sensor device.

A context awareness architecture for facilitating mobile learning

Abstract: The MOBIlearn project (EU IST-2001-37187) aims to support a wide range of services and applications for learners using mobile computing devices such as phones, PDAs, and laptops The display limitations of these devices mean that it is crucial to deliver the right content at the right time One way of doing this is to use contextual information to derive content that is relevant to what the user is doing, as well as where and how they are doing it We present an object-oriented, feature-based architecture for a context awareness subsystem to be implemented within the MOBIlearn project, and consider the implications involved in the use of such a system for mobile learning

Context attributes: an approach to enable context-awareness for service discovery

Abstract: The service discovery problem has attracted a lot of attention from researchers and practitioners. Jini, SLP, and UPnP are among the few emerging service discovery protocols. Although they seem to provide a good solution to the problem, there is an unaddressed need of more sophisticated location and context-aware service selection support. In this paper, we introduce the concept of context attribute as an effective, flexible means to exploit relevant context information during the service discovery process. Context attributes can express context information including service-specific selection logic, client, and network condition. We describe our approach and implementation, and present experimental results of our context-aware service discovery implementation.

Enabling location-aware pervasive computing applications for the elderly

Abstract: The Pervasive Computing Laboratory at the University of Florida is dedicated to creating smart environments and assistants to enable elderly persons to live a longer and a more independent life at home. By achieving this goal, technology will increase the chances of successful aging despite an ailing health care system (e.g. Medicaid). One of the essential services required to maximize the intelligence of a smart environment is an indoor precision tracking system. Such system allows the smart home to make proactive decisions to better serve its occupants by enabling context-awareness instead of being solely reactive to their commands. This paper presents our hands-on experience and lessons learnt from our first phase work to build up a smart home infrastructure for the elderly. We review location tracking technology and describe the rationale behind our choice of the emerging ultrasonic sensor technology. We give an overview of the House of Matilda (an in-laboratory mock up house) and describe our design of a precision in-door tracking system. We also describe an OSGi-based robust framework that abstracts the ultrasonic technology into a standard service to enable the creation of tracking based applications by third party, and to facilitate the collaboration among various devices and other OSGi services. Finally, we describe three pervasive computing applications that use the location-tracking system which we have implemented in Matilda's house.

Location management in pervasive systems

Abstract: Pervasive systems require context awareness in order to be able to provide "anywhere, anytime" computing to mobile users. One type of context information is location information: pervasive systems require knowledge of the location of users, devices and services. This paper reviews location management for pervasive systems. The review is based on our experience in the development of a location management system. Issues discussed include the types of location sensors (which are categorised as physical, virtual or logical); the processing of location information; and an architecture for a location management system. Three issues of ongoing importance are discussed in greater detail. These are location conflict resolution (i.e., how can the location of an entity be determined when multiple sensors provide conflicting information); the security and privacy of location information; and scalability issues in location management.

Bayesian approach to sensor-based context awareness

Abstract: The usability of a mobile device and services can be enhanced by context awareness. The aim of this experiment was to expand the set of generally recognizable constituents of context concerning personal mobile device usage. Naive Bayesian networks were applied to classify the contexts of a mobile device user in her normal daily activities. The distinguishing feature of this experiment in comparison to earlier context recognition research is the use of a naive Bayes framework, and an extensive set of audio features derived partly from the algorithms of the upcoming MPEG-7 standard. The classification was based mainly on audio features measured in a home scenario. The classification results indicate that with a resolution of one second in segments of 5–30 seconds, situations can be extracted fairly well, but most of the contexts are likely to be valid only in a restricted scenario. Naive Bayes framework is feasible for context recognition. In real world conditions, the recognition accuracy using leave-one-out cross validation was 87% of true positives and 95% of true negatives, averaged over nine eight-minute scenarios containing 17 segments of different lengths and nine different contexts. Respectively, the reference accuracies measured by testing with training data were 88% and 95%, suggesting that the model was capable of covering the variability introduced in the data on purpose. Reference recognition accuracy in controlled conditions was 96% and 100%, respectively. However, from the applicability viewpoint, generalization remains a problem, as from a wider perspective almost any feature may refer to many possible real world situations.

An ontology for mobile device sensor-based context awareness

Abstract: In mobile computing, the efficient utilisation of the information gained from the sensors embedded in the devices is difficult. Instead of using raw measurement data application specifically, as currently is customary, higher abstraction level semantic descriptions of the situation, context, can be used to develop mobile applications that are more usable. This article introduces an ontology of context constituents, which are derived from a set of sensors embedded in a mobile device. In other words, a semantic interface to the sensor data is provided. The ontology promotes the rapid development of mobile applications, more efficient use of resources, as well as reuse and sharing of information between communicating entities. A few mobile applications are presented to illustrate the possibilities of using the ontology.

Location- and Time-Based Information Delivery in Tourism

Abstract: Today’s mobile devices allow end users to get information related to a particular domain based on their current location, such as the fastest route to the nearest drugstore. However, in such Location-Based Services (LBS), richer and more targeted information is desirable. In many applications, end users would like to be notified about relevant events or places to visit in the near future according to their profile. They also do not wish to get the same information many times unless they explicitly ask for it. In this paper, we describe our system, TIP (Tourism Information Provider), which delivers various types of information to mobile devices based on location, time, profile of end users, and their “history”, i.e., their accumulated knowledge. The system hinges on a hierarchical semantic geospatial model as well as on an Event Notification System (ENS).

Location aware resource management in smart homes

Abstract: The rapid advances in a wide range of wireless access technologies along with the efficient use of smart spaces have already set the stage for the development of smart homes. Context-awareness is perhaps the most salient feature in these intelligent computing platforms. The "location" information of the users plays a vital role in defining this context. To extract the best performance and efficacy of such smart computing environments, one needs a scalable, technology-independent location service. We have developed a predictive framework for location-aware resource optimization in smart homes. The underlying compression mechanism helps in efficient learning of an inhabitant's movement (location) profiles in the symbolic domain. The concept of Asymptotic Equipartition Property (AEP) in information theory helps to predict the inhabitant's future location as well as most likely path-segments with good accuracy. Successful prediction helps in pro-active resource management and on-demand operations of automated devices along the inhabitant's future paths and locations - thus providing the necessary comfort at a near-optimal cost. Simulation results on a typical smart home floor plans corroborate this high prediction success and demonstrate sufficient reduction in daily energy-consumption, manual operations and time spent by the inhabitant which are considered as a fair measure of his/her comfort.

Research Issues in Ad-Hoc Distributed Personal Networking

Abstract: This paper discusses the research issues that need to be addressed in order to create a personal distributed environment where people interact with various companion, embedded, or invisible computers not only in their close vicinity but potentially anywhere. These systems are called personal networks (PNs). They constitute a category of distributed systems with very specific characteristics. They are configured in an ad hoc fashion, as the opportunity and the demand arise, to support personal applications. PNs consist of communicating clusters of personal digital devices, devices shared with other people and even infrastructure-based systems. At the heart of a PN is a core Personal Area Network (PAN), which is physically associated with the owner of the PN. Unlike the present PANs that have a geographically limited coverage, the Personal Operating Space, PNs have an unrestricted geographical span, and incorporate devices into the personal environment regardless of their geographic location. In order to do this they need the services of infrastructure-based networks and ad-hoc networks to extend their reach. A PN extends and complements the concept of pervasive computing. We show that PNs introduce new design challenges due to the heterogeneity of the involved technologies, the need for self-organization, the dynamics of the system composition, the application-driven nature, the co-operation with infrastructure-based networks, and the security hazards. We discuss the impact of these problems on network design, assess present and proposed solutions, and identify the research issues.

User-centric content negotiation for effective adaptation service in mobile computing

Abstract: We address the challenges of building a good content adaptation service for mobile devices and propose a decision engine that is user-centric with QoS awareness, which can automatically negotiate for the appropriate adaptation decision to use in the synthesis of an optimal adapted version. The QoS-sensitive approach complements the lossy nature of the transcoding operations. The decision engine will look for the best trade off among various parameters in order to reduce the loss of quality in various domains. Quantitative methods are suggested to measure the QoS of the content versions in various quality domains. Based on the particular user perception and other contextual information on the client capability, the network connection, and the requested content, the proposed negotiation algorithm will determine a content version with a good aggregate score. We have built a prototype document adaptation system for PDF documents to demonstrate the viability of our approach.

Context Awareness using Environmental Noise Classification

Abstract: Context-awareness is essential to the development of adaptive information systems. Environmental noise can provide a rich source of information about the current context. We describe our approach for automatically sensing and recognising noise from typical environments of daily life, such as office, car and city street. In this paper we present our hidden Markov model based noise classifier. We describe the architecture of the system, compare classification results from the system with human listening tests, and discuss open issues in environmental noise classification for mobile computing.

A semantic E-wallet to reconcile privacy and context awareness

Abstract: Increasingly, application developers are looking for ways to provide users with higher levels of personalization that capture different elements of a user's operating context, such as her location, the task that she is currently engaged in, who her colleagues are, etc. While there are many sources of contextual information, they tend to vary from one user to another and also over time. Different users may rely on different location tracking functionality provided by different cell phone operators; they may use different calendar systems, etc. In this paper, we describe work on a Semantic e-Wallet aimed at supporting automated discovery and access of personal resources, each represented as a Semantic Web Service. A key objective is to provide a Semantic Web environment for open access to a user's contextual resources, thereby reducing the costs associated with the development and maintenance of context-aware applications. A second objective is, through Semantic Web technologies, to empower users to selectively control who has access to their contextual information and under which conditions. This work has been carried out in the context of myCampus, a context-aware environment aimed at enhancing everyday campus life. Empirical results obtained on Carnegie Mellon's campus are encouraging.

The NIST Smart Space and Meeting Room projects: signals, acquisition annotation, and metrics

Abstract: Pervasive computing devices, sensors, and networks, provide infrastructure for context aware smart meeting rooms that sense ongoing human activities and respond to them. This requires advances in areas including networking, distributed computing, sensor data acquisition, signal processing, speech recognition, human identification, and natural language processing. Open interoperability and metrology standards for the sensor and recognition technologies can aid R&D programs in making these advances. The NIST (National Institute of Standards and Technology) Smart Space and Meeting Room projects are developing tools for data formats, transport, distributed processing, and metadata. We are using them to create annotated multi modal research corpora and measurement algorithms for smart meeting rooms, which we are making available to the research and development community.

HyCon: a framework for context-aware mobile hypermedia

Abstract: This paper introduces the notion of context-aware mobile hypermedia. Context awareness means to take the users' context such as location, time, objective, community relations, etc., into account when browsing, searching, annotating, and linking. Attributes constituting the context of the user may be sensed automatically and/or be provided by the user directly. When mobile, the user may obtain context-aware hypermedia support on a variety of small and medium sized computing platforms such as mobile phones, PDAs, tablet PCs, and laptops. This paper introduces the HyCon (HyperContext) framework with an architecture for context-aware hypermedia. The architecture includes interfaces for a sensor tier encapsulating relevant sensors and represents the hypermedia objects in structures based on the XLink and RDF standards. A prototype called the HyConExplorer created with the framework is presented, and it is illustrated how the classical hypermedia features such as browsing, searching, annotating, linking, and collaboration are supported in context-aware hypermedia. Among the features of the HyConExplorer are real-time location-based searches via Google collecting hits within a specified nimbus around the user's GPS position. Finally, the use of scenarios for and evaluation of the use of the HyConExplorer in public school projects are discussed.

Dynamic binding in mobile applications

Abstract: By separating binding concerns from application logic, the Colomba approach exploits metadata to let mobile applications adapt to dynamic environments Colomba separates service logic from binding management This permits developers to code, change, and reuse service components and binding strategies independently of each other Administrators can express binding strategies at a high level of abstraction in terms of declarative policies In particular, Colomba supports a dynamic binding management that requires: Context awareness is the knowledge of application-specific attributes, such as user preferences, level of trust, subscribed services, and access device characteristics Users can refer to a set of resources determined by context information Location awareness is the knowledge of the physical position of the user or device connection to the network infrastructure Available resources depend on location information

Location-dependent services for mobile users

Abstract: One of the main issues in mobile services' research (M-service) is supporting M-service availability, regardless of the user's context (physical location, device employed, etc.). However, most scenarios also require the enforcement of context-awareness, to dynamically adapt M-services depending on the context in which they are requested. In this paper, we focus on the problem of adapting M-services depending on the users' location, whether physical (in space) or logical (within a specific distributed group/application). To this end, we propose a framework to model users' location via a multiplicity of local and active service contexts. First, service contexts represent the mean to access to M-services available within a physical locality. This leads to an intrinsic dependency of M-service on the users' physical location. Second, the execution of service contexts can be tuned depending on who is requesting what M-service. This enables adapting M-services to the logical location of users (e.g., a request can lead to different executions for users belonging to different groups/applications). The paper firstly describes the framework in general terms, showing how it can facilitate the design of distributed applications involving mobile users as well as mobile agents. Then, it shows how the MARS coordination middleware, implementing service contexts in terms of programmable tuple spaces, can be used to develop and deploy applications and M-services coherently with the above framework. A case study is introduced and discussed through the paper to clarify our approach and to show its effectiveness.

Experiments with multi-modal interfaces in a context-aware city guide

Abstract: In recent years there has been considerable research into the development of mobile context-aware applications. The canonical example of such an application is the context-aware tour-guide that offers city visitors information tailored to their preferences and environment. The nature of the user interface for these applications is critical to their success. Moreover, the user interface and the nature and modality of information presented to the user impacts on many aspects of the system’s overall requirements, such as screen size and network provision. Current prototypes have used a range of different interfaces developed in a largely ad-hoc fashion and there has been no systematic exploration of user preferences for information modality in mobile context-aware applications. In this paper we describe a series of experiments with multi-modal interfaces for context-aware city guides. The experiments build on our earlier research into the GUIDE system and include a series of field trials involving members of the general public. We report on the results of these experiments and extract design guidelines for the developers of future mobile context-aware applications.

Context-awareness in user modelling: requirements analysis for a case-based reasoning application

Abstract: The paper describes an approach of using the case-based reasoning methodology in context-aware systems. It elaborates how this technique can be applied to generate recommendations based on the contexts of users respectively objects especially in a mobile scenario. By combining case-based reasoning methodology and context awareness a new and powerful way of modelling and reasoning from contexts emerges. Using cases to enclose contexts will enhance the possibilities to compare contexts, determine certain values of context-similarities, and reflect this information in the process of generating recommendations. Furthermore, this contribution tries to show how the users' behaviour can be learnt in a case-based fashion and how the users' way of thinking can be simulated.

Lino, the User-Interface Robot

Abstract: This paper reports on the development of a domestic user-interface robot that is able to have a natural human interaction by speech and emotional feedback and is able to navigate in a home environment. The natural interaction with the user is achieved by means of a mechanical head able to express emotions. The robot is aware of the position and identities of the users, both from visual and auditory information. The robot estimates its location in the environment with an appearance-based localization method using a stereo camera system. The navigation to the goal is achieved with a hybrid method, combining planning with reactive control. The robot is designed to operate in an intelligent environment, such that external information can be used to localize users and their intentions (context awareness), and that additional information can be retrieved from various databases in the environment. The result is a service robot that can have a simple dialogue with the user, provide information in a natural way (speech and expressions) and can be instructed to navigate to any specific goal in the environment.