Context-aware computing is a mobile computing paradigm in which applications can discover and take advantage of contextual information (such as user location, time of day, nearby people and devices, and user activity). Since it was proposed about a decade ago, many researchers have studied this topic and built several context-aware applications to demonstrate the usefulness of this new technology. Context-aware applications (or the system infrastructure to support them), however, have never been widely available to everyday users. In this survey of research on context-aware systems and applications, we looked in depth at the types of context used and models of context information, at systems that support collecting and disseminating context, and at applications that adapt to the changing context. Through this survey, it is clear that context-aware research is an old but rich area for research. The difficulties and possible solutions we outline serve as guidance for researchers hoping to make context-aware computing a reality. 1.

this article we focus on the issues pertinent to software designers without delving into the lower level details of the hardware realization of mobile computers. We look at some promising approaches under investigation and also consider their limitations. The many issues to be dealt with stem from three essential properties of mobile computing: communication, mobility, and portability. Of course, special-purpose systems may avoid some design pressures by doing without certain desirable properties. For instance, portability would be less of a concern for mobile computers installed in the dashboards of cars than with hand-held mobile computers. However, we concentrate on the goal of large-scale, hand-held mobile computing as a way to reveal a wide assortment of issues

. The proliferation ofcomputing into the physical world promises more than the ubiquitous availability of computing infrastructure; it suggests new paradigms of interaction inspired by constant access to information and computational capabilities. For the past decade, applicationdriven research in ubicomp has pushed three interaction themes: natural interfaces, context-aware applications, and automated capture and access. To chart a course for future research in ubiquitous computing, we review the accomplishments of these efforts and point to remaining research challenges. Research in ubiquitous computing implicitly requires addressing some notion of scale; whether in the number and type of devices, the physical space of distributed computing or the number of people using a system. We posit a new area of applications research, everyday computing, focussed on scaling interaction with respect to time. Just as pushing the availability of computing away from the traditional desktop fun...

There has been increased research interest in systems composed of multiple autonomous mobile robots exhibiting collective behavior. Groups of mobile robots are constructed, with an aim to studying such issues as group architecture, resource conflict, origin of cooperation, learning, and geometric problems. As yet, few applications of collective robotics have been reported, and supporting theory is still in its formative stages. In this paper, we give a critical survey of existing works and discuss open problems in this field, emphasizing the various theoretical issues that arise in the study of cooperative robotics. We describe the intellectual heritages that have guided early research, as well as possible additions to the set of existing motivations. 1

To take advantage of the full potential of ubiquitous computing, we will need systems which minimize powerconsumption. Weiser et al. and others have suggested that this may be accomplished by a CPU which dynamically changes speed and voltage, thereby saving energy by spreading run cycles into idle time. Here we continue this research, using a simulation to compare a number of policies for dynamic speed-setting. Our work clarifies a fundamental power vs. delay tradeoff, as well as the role of prediction and of smoothing in dynamic speed-setting policies. We conclude that success seemingly depends more on simple smoothing algorithms than on sophisticated prediction techniques, but defer to the replication of these results on future variable-speed systems. 1 Introduction Recent developments in ubiquitous computing make it likely that the future will see a proliferation of cordless computing devices. Clearly it will be advantageous for such devices to minimize power-consumption. The top p...

We present a method for searching in an image database using a query image that is similar to the intended target. The query image may be a hand-drawn sketch or a (potentially low-quality) scan of the image to be retrieved. Our searching algorithm makes use of multiresolution wavelet decompositions of the query and database images. The coefficients of these decompositions are distilled into small "signatures" for each image. We introduce an "image querying metric" that operates on these signatures. This metric essentially compares how many significant wavelet coefficients the query has in common with potential targets. The metric includes parameters that can be tuned, using a statistical analysis, to accommodate the kinds of image distortions found in different types of image queries. The resulting algorithm is simple, requires very little storage overhead for the database of signatures, and is fast enough to be performed on a database of 20,000 images at interactive rates (on standard...

One potentially useful feature of future computing environments is the ability to capture the live experiences of the occupants and to provide that record to users for later access and review. Over the last 3 years, we have designed and extensively used a particular instrumented environment, the classroom, designed to facilitate the easy capture of the traditional lecture experience. We will describe the history of the Classroom 2000 project at Georgia Tech, and provide results of extended evaluations of the impact of automated capture on the teaching and learning experience. In addition to understanding the impact of automated capture in this educational domain, there are many important lessons to take away from this long-term, largescale experiment with a living ubiquitous computing environment. The environment needs to address issues of scale and extensibility, and there needs to be a way to continuously evaluate the effectiveness of the environment and understand and react to the w...

The reduction of energy consumption in microprocessors can be accomplished without impacting the peak performance through the use of dynamic voltage scaling (DVS). This approach varies the processor voltage under software control to meet dynamically varying performance requirements. This paper presents a foundation for the simulation and analysis of DVS algorithms. These algorithms are applied to a benchmark suite specifically targeted for PDA devices. 2.

We describe the i-LAND environment which constitutes an example of our vision of the workspaces of the future, in this case supporting cooperative work of dynamic teams with changing needs. i-LAND requires and provides new forms of human-computer interaction and new forms of computer-supported cooperative work. Its design is based on an integration of information and architectural spaces, implications of new work practices and an empirical requirements study informing our design. i-LAND consists of several ‘roomware ’ components, i.e. computer-augmented objects integrating room elements with information technology. We present the current realization of i-LAND in terms of an interactive electronic wall, an interactive table, two computer-enhanced chairs, and two “bridges” for the Passage-mechanism. This is complemented by the description of the creativity support application and the technological infrastructure. The paper is accompanied by a video figure in the CHI’99 video program.

... This paper describes the Ubiquitous Computing philosophy, the PARCTAB system, user-interface issues for small devices, and our experience developing and testing a variety of mobile applications.