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One of the challenges for ubiquitous computing is to design systems that can be both understood by their users and at the same time understand the users themselves. As information and its meaning becomes more associated with the communities that provide and use it, how will it be possible to build effective systems for these users? We have been examining these issues via ethnographic analysis of the information and community supporting system that we have developed and employed at conference events. This paper presents initial analysis and suggests greater focus on the interaction between members of micro-communities of users in future ubicomp research. [ABSTRACT FROM AUTHOR]

Over the last decade, new information and communication technologies have lived a secret life. For individuals and institutions around the world, this constellation of mobile phones, personal computers, the internet, software, games, and other computing objects have supported a complex set of religious and spiritual needs. In this paper, I offer a survey of emerging and emergent techno-spiritual practices, and the anxieties surrounding their uptake. I am interested in particular in the ways in which religious uses of technology represent not only a critique of dominant visions of technology's futures, but also suggest a very different path(s) for ubiquitous computing's technology envisioning and development. [ABSTRACT FROM AUTHOR]

Recognition of everyday physical activities is difficult due to the challenges of building informative, yet unobtrusive sensors. The most widely deployed and used mobile computing device today is the mobile phone, which presents an obvious candidate for recognizing activities. This paper explores how coarse-grained GSM data from mobile phones can be used to recognize high-level properties of user mobility, and daily step count. We demonstrate that even without knowledge of observed cell tower locations, we can recognize mobility modes that are useful for several application domains. Our mobility detection system was evaluated with GSM traces from the everyday lives of three data collectors over a period of one month, yielding an overall average accuracy of 85%, and a daily step count number that reasonably approximates the numbers determined by several commercial pedometers. [ABSTRACT FROM AUTHOR]

In this paper, we propose a simulator for facilitating reliable and inexpensive development of ubiquitous applications where each application software controls a lot of information appliances based on the state of external environment, user's contexts and preferences. The proposed simulator realistically reproduces behavior of application software on virtual devices in a virtual 3D space. For this purpose, the simulator provides functions to facilitate deployment of virtual devices in a 3D space, simulates communication among the devices from MAC level to application level, and reproduces the change of physical quantities (e.g., temperature) caused by devices (e.g., air conditioners). Also, we keep software portability between virtual devices and real devices. As the most prominent function of the simulator, we provide a systematic and visual testing method for testing whether a given application software satisfies specified requirements. [ABSTRACT FROM AUTHOR]

Real world recommendation systems, personalized mobile search, and online city guides could all benefit from data on personal place preferences. However, collecting explicit rating data of locations as users travel from place to place is impractical. This paper investigates the relationship between explicit place ratings and implicit aspects of travel behavior such as visit frequency and travel time. We conducted a four-week study with 16 participants using a novel sensor-based experience sampling tool, called My Experience (Me), which we developed for mobile phones. Over the course of the study Me was used to collect 3,458 in-situ questionnaires on 1,981 place visits. Our results show that, first, sensor-triggered experience sampling is a useful methodology for collecting targeted information in situ. Second, despite the complexities underlying travel routines and visit behavior, there exist positive correlations between place preference and automatically detectable features like visit frequency and travel time. And, third, we found that when combined, visit frequency and travel time result in stronger correlations with place rating than when measured individually. Finally, we found no significant difference in place ratings due to the presence of others. [ABSTRACT FROM AUTHOR]

This paper examines the positioning accuracy of a GSM beacon-based location system in a metropolitan environment. We explore five factors effecting positioning accuracy: location algorithm choice, scan set size, simultaneous use of cells from different providers, training and testing on different devices, and calibration data density. We collected a 208-hour, 4350Km driving trace of three different GSM networks covering the Seattle metropolitan area. We show a median error of 94m in downtown and 196m in residential areas using a single GSM network and the best algorithm for each area. Estimating location using multiple providers' cells reduces median error to 65-134 meters and 95% error to 163m in the downtown area, which meets the accuracy requirements for E911. We also show that a small 60-hour calibration drive is sufficient for enabling a metropolitan area similar to Seattle. [ABSTRACT FROM AUTHOR]

This paper presents a novel ubiquitous computing device, the SenseCam, a sensor augmented wearable stills camera. SenseCam is designed to capture a digital record of the wearer's day, by recording a series of images and capturing a log of sensor data. We believe that reviewing this information will help the wearer recollect aspects of earlier experiences that have subsequently been forgotten, and thereby form a powerful retrospective memory aid. In this paper we review existing work on memory aids and conclude that there is scope for an improved device. We then report on the design of SenseCam in some detail for the first time. We explain the details of a first in-depth user study of this device, a 12-month clinical trial with a patient suffering from amnesia. The results of this initial evaluation are extremely promising; periodic review of images of events recorded by SenseCam results in significant recall of those events by the patient, which was previously impossible. We end the paper with a discussion of future work, including the application of SenseCam to a wider audience, such as those with neurodegenerative conditions such as Alzheimer's disease. [ABSTRACT FROM AUTHOR]

This paper presents an analysis, implementation and evaluation of the physical mobile interaction techniques touching, pointing and scanning. Based on this we have formulated guidelines that show in which context which interaction technique is preferred by the user. Our main goal was to identify typical situations and scenarios in which the different techniques might be useful or not. In support of these aims we have developed and evaluated, within a user study, a low-fidelity and a high-fidelity prototype to assess scanning, pointing and touching interaction techniques within different contexts. Other work has shown that mobile devices can act as universal remote controls for interaction with smart objects but, to date, there has been no research which has analyzed when a given mobile interaction technique should be used. In this research we analyze the appropriateness of three interaction techniques as selection techniques in smart environments. [ABSTRACT FROM AUTHOR]

In this paper, we are concerned with the detection software faults and tampering of the mobile application as well as the mobile device theft. We want to disable mobile device cryptographically once either of these problems are detected. Basically the device needs to receive a new cryptographic key after each pre-set period of time in order to continue function. The mobile application execution integrity is checked by the authority when deciding whether or not to give out a new key. The detection can be done via a run-time result checking when the device connects to the authority. The authority can also proactively examine whether or not software tampering is happening. This paper will show approaches that each standalone can improve the dependability and security of a mobile application. We will show how these approaches can work together seamlessly to form a stronger scheme. [ABSTRACT FROM AUTHOR]

A motivation behind much UbiComp research has been to make our lives convenient, comfortable and informed, following in the footsteps of Weiser's calm computing vision. Three themes that have dominated are context awareness, ambient intelligence and monitoring/tracking. While these avenues of research have been fruitful their accomplishments do not match up to anything like Weiser's world. This paper discusses why this is so and argues that is time for a change of direction in the field. An alternative agenda is outlined that focuses on engaging rather than calming people. Humans are very resourceful at exploiting their environments and extending their capabilities using existing strategies and tools. I describe how pervasive technologies can be added to the mix, outlining three areas of practice where there is much potential for professionals and laypeople alike to combine, adapt and use them in creative and constructive ways. Keywords: calm computing, Weiser, user experiences, engaged living, Ubi- Comp history, pervasive technologies, proactive computing. [ABSTRACT FROM AUTHOR]

We present WISP, a wireless, battery-free platform for sensing and computation that is powered and read by a standards compliant Ultra-High Frequency (UHF) RFID reader. To the reader, the WISP appears to be an ordinary RFID tag. The WISP platform includes a general-purpose programmable flash microcontroller and implements the bi-directional communication primitives required by the Electronic Product Code (EPC) RFID standard, which allows it to communicate arbitrary sensor data via an EPC RFID reader by dynamically changing the ID it presents to the reader. For each 64 bit "packet," the WISP's microcontroller dynamically computes the 16-bit CRC that the EPC standard requires of valid packets. Because the WISP device can control all bits of the presented ID, 64 bits of sensor data can be communicated with a single RFID read event. As an example of the system in operation, we present 13 hours of continuous-valued light-level data measured by the device. All the measurements were made using power harvested from the RFID reader. No battery, and no wired connections (for either power or data) were used. As far as we are aware, this paper reports the first fully programmable computing platform that can operate using power transmitted from a long-range (UHF) RFID reader and communicate arbitrary, multi-bit data in response to a single RFID reader poll event. [ABSTRACT FROM AUTHOR]

Effective ubiquitous computing applications need to integrate users' personal devices and data with the devices and resources they encounter around them. Previous work addressed this problem by simply enabling the user to take all of their data with them wherever they go. In this paper, we present a more flexible approach: the "instant matchmaker", a personal device that allows a user to seamlessly and securely connect his local computing environment with his other personal resources, wherever they are. The matchmaker provides an intuitive user experience, while simultaneously enabling extremely fine-grained control over access to resources. We have implemented a cellphone-based matchmaker and explored its use in a secure media sharing application. The matchmaker concept, however, is general, and can be used to enable a range of appealing and secure ubicomp applications. [ABSTRACT FROM AUTHOR]

Ubiquitous computing technologies create new opportunities for preventive healthcare researchers to deploy behavior modification strategies outside of clinical settings. In this paper, we describe how strategies for motivating behavior change might be embedded within usage patterns of a typical electronic device. This interaction model differs substantially from prior approaches to behavioral modification such as CD-ROMs: sensor-enabled technology can drive interventions that are timelier, tailored, subtle, and even fun. To explore these ideas, we developed a prototype system namedViTo. On one level, ViTo functions as a universal remote control for a home entertainment system. The interface of this device, however, is designed in such a way that it may unobtrusively promote a reduction in the user's television viewing while encouraging an increase in the frequency and quantity of non-sedentary activities. The design of ViTo demonstrates how a variety of behavioral science strategies for motivating behavior change can be carefully woven into the operation of a common consumer electronic device. Results of an exploratory evaluation of a single participant using the system in an instrumented home facility are presented. [ABSTRACT FROM AUTHOR]

Context-aware computing is a central concept in ubiquitous computing and many suggestions for context-aware technologies and applications have been proposed. There is, however, little evidence on how these concepts and technologies play out in a real-world setting. In this paper we describe and discuss our experiences from an ongoing deployment of a suite of context-aware technologies and applications in a hospital environment, including a context-awareness infrastructure, a location tracking system, and two context-aware applications running on interactive wall displays and mobile phones. Based on an analysis of the use of these systems, we observe that many of the ideas behind context-aware computing are valid, and that the context-aware applications are useful for clinicians in their work. By reflecting on the nature of the designed context-aware technologies, we present a model which states that the triggering of context-awareness actions depend upon the accuracy of the sensed context information, the degree to which you know which action to perform in a given situation, and the consequence of performing the action. [ABSTRACT FROM AUTHOR]

Drawing on Value Sensitive Design, we developed a workable privacy addendum for an open source software license that not only covers intellectual property rights while allowing software developers to modify the software (the usual scope of an open source license), but also addresses end-user privacy. One central innovation of our work entails the integration of an informed consent model and a threat model for developing privacy protections for ubiquitous location aware systems. We utilized technology that provided a device's location information in real-time: Intel's POLS, a "sister" system to Intel's Place Lab. In January 2006, POLS was released under a license combining the substantive terms of the Eclipse Public License together with this privacy addendum. In this paper, we describe how we developed the privacy addendum, present legal terms, and discuss characteristics of our design methods and results that have implications for protecting privacy in ubiquitous information systems released in open source. [ABSTRACT FROM AUTHOR]

This paper reports on issues related to the use of mobile phones by women aged 60 years and over. The study started with a series of focus group discussions, which covered usage patterns, problems, benefits, ideal phone design, and desired and unwanted features. It then moved to an exploration of the group's cooperative learning process when encountering an unfamiliar mobile phone. The issues raised in the discussions were translated into an online questionnaire, which was responded to by 67 women aged 60 and over. This study makes two main contributions to the field. First, it is one of a very few studies that provides a diagrammatic representation of older mobile phone female users' cooperative learning process and strategies. Second, the study presents a combination of quantitative and qualitative data, which provides more nuanced interpretation and understanding of the use of mobile phones by older women. Keywords: Elderly, mobile phone, older adults, focus group, questionnaire. [ABSTRACT FROM AUTHOR]

People who are deaf or hard-of-hearing may have challenges communicating with others via spoken words and may have challenges being aware of audio events in their environments. This is especially true in public places, which may not have accessible ways of communicating announcements and other audio events. In this paper, we present the design and evaluation of a mobile sound transcription tool for the deaf and hard-of-hearing. Our tool, Scribe4Me, is designed to improve awareness of sound-based information in any location. When a button is pushed on the tool, a transcription of the last 30 seconds of sound is given to the user in a text message. Transcriptions include dialog and descriptions of environmental sounds. We describe a 2-week field study of an exploratory prototype, which shows that our approach is feasible, highlights particular contexts in which it is useful, and provides information about what should be contained in transcriptions. [ABSTRACT FROM AUTHOR]

Seeking to be sensitive to users, smart home researchers have focused on the concept of control. They attempt to allow users to gain control over their lives by framing the problem as one of end-user programming. But families are not users as we typically conceive them, and a large body of ethnographic research shows how their activities and routines do not map well to programming tasks. End-user programming ultimately provides control of devices. But families want more control of their lives. In this paper, we explore this disconnect. Using grounded contextual fieldwork with dual-income families, we describe the control that families want, and suggest seven design principles that will help end-user programming systems deliver that control. [ABSTRACT FROM AUTHOR]

Ubicomp developers are increasingly borrowing from other disciplines, such as anthropology and creative design, to inform their design process. In this paper, we demonstrate that the discipline of history similarly has much to offer ubicomp research. Specifically, we describe a historically-grounded approach to designing ubicomp systems and applications for the home. We present findings from a study examining aging and housework that demonstrate how our approach can be useful to sensitize ubicomp developers to the impact of cultural values on household technology, to reunderstand the home space, and to spur development of new design spaces. Our findings suggest that historically-grounded research approaches may be useful in more deeply understanding and designing for context both in and outside of the home. [ABSTRACT FROM AUTHOR]

The paper reports the results of the first stage of our work on an automatic dietary monitoring system. The work is part of a large European project on using ubiquitous systems to support healthy lifestyle and cardiovascular disease prevention. We demonstrate that sound from the user's mouth can be used to detect that he/she is eating. The paper also shows how different kinds of food can be recognized by analyzing chewing sounds. The sounds are acquired with a microphone located inside the ear canal. This is an unobtrusive location widely accepted in other applications (hearing aids, headsets). To validate our method we present experimental results containing 3500 seconds of chewing data from four subjects on four different food types typically found in a meal. Up to 99% accuracy is achieved on eating recognition and between 80% to 100% on food type classification. [ABSTRACT FROM AUTHOR]

The vision of a landscape of heterogeneous web services deployed as encapsulated business software assets in the Internet is currently becoming a reality as part of the Semantic Web. When pro-active agents handle the context-aware discovery, acquisition, composition, and management of application services and data, ensuring the security of customers' data becomes a principle task. To dynamically compose its offered service, an agent has to process and spread confidential data to other web services demanding the required degree of security. In this paper we propose a methodology based on type-based information flow to control the security of dynamically computed data and their proliferation to other web services. [ABSTRACT FROM AUTHOR]

In a wireless communication network, it is possible to locate a user and track its trajectory based on its transmission, during communication with access points. This type of tracking leads to the breach of a user's location privacy. Prior solutions to this problem enhances user's location privacy at the expense of communication Quality of Service(QoS) degradation. In this paper, we propose silent cascade to enhance a user' location privacy by trading users' delay in silent cascade for anonymity. As a result, it avoids the problem of QoS degradation in prior solutions. Furthermore, we abstract silent cascade as a mix-network based formal model, and use this model to evaluate the performance of silent cascade. Study results prove the effectiveness of silent cascade under different types of QoS requirements. Besides, we also derive the optimal configuration of silent cascade to achieves target anonymity within minimum duration of time. and the theoretical upper bound of a silent cascade's anonymity. [ABSTRACT FROM AUTHOR]

Increasing automation of buildings enables rich information streams about the activities of building users to reach networked computer systems. Privacy concerns typically cause this information to be accessible only by building managers and security personnel. However, if appropriate privacy mechanisms can be implemented, then it is possible to deploy location information systems that can contribute to the convenience and efficiency of users. This paper describes a three step approach to privacy-sensitive release of location information collected by building sensors. These steps entail defining an ownership model, defining environment events to be monitored, and creating a sharing model. These steps are described mathematically and then validated through a case study for a system called Janus's Map which provides a location information system for the card reader, door, and occupancy sensors of a modern smart building. [ABSTRACT FROM AUTHOR]

This paper addresses the need for individualized information anytime and anyplace in contrast to the problem of user's right to privacy. The creation and application of profiles is characterized. A extensible middleware approach is proposed to combine independent databases on localization and personal profiles in order to identify the right layer to protect privacy. This will enable telecommunication providers to offer common basic services for the development of a wide range of mobile 3rd party applications. [ABSTRACT FROM AUTHOR]

Multivariate (or ) public-key cryptosystems (PKC) are alternatives to traditional PKCs based on large algebraic structures (e.g., RSA and ECC); they usually execute much faster than traditional PKCs on the same hardware. However, one major challenge in implementing multivariates in embedded systems is that the key size can be prohibitively large for applications with stringent resource constraints such as low-cost smart cards, sensor networks (e.g., Berkeley motes), and radio-frequency identification (RFID). In this paper, we investigate strategies for shortening the key of a multivariate PKC. We apply these strategies to the Tame Transformation Signatures (TTS) as an example and quantify the improvement in key size and running speed, both theoretically and via implementation. We also investigate ways to save die space and energy consumption in hardware, reporting on our ASIC implementation of TTS on a TSMC 0.25μm process. Even without any key shortening, the current consumption of TTS is only 21 μA for computing a signature, using 22,000 gate equivalents and 16,000 100-kHz cycles (160 ms). With circulant-matrix key shortening, the numbers go down to 17,000 gates and 4,400 cycles (44 ms). We therefore conclude: besides representing a future-proofing investment against the emerging quantum computers, multivariates can be immediately useful in niches. Keywords: Multivariate public-key cryptosystem, efficient implementation, digital signature schemes, embedded system, sensor networks, motes. [ABSTRACT FROM AUTHOR]

The pervasive computing paradigm assumes an essentially dynamic model of interaction between devices that also motivates the need to discover the services offered by previously unknown parties at an early phase of these interactions. Whereas this assumption is at the heart of many pervasive computing protocols and systems, the necessity of securing service discovery and the complexity of this task have been largely underestimated, if considered at all. This paper discusses the implications of insecure service discovery in available systems and which security objectives should be pursued. The design space for introducing security features into a specific architecture, namely registry-based discovery systems, is then explored and assessed. [ABSTRACT FROM AUTHOR]

In this paper, we consider a multi-layer mobile ad-hoc network (MANET) composed of several kinds of networking units (such as ground soldiers, tanks, and unmanned aerial vehicles) with heterogeneous resources to communicate and compute. In this multi-layer MANET, we first propose a password-based authenticated group key exchange scheme with members' different passwords. The proposed scheme only requires constant-round to generate a group session key under the dynamic scenario, hence it is scalable, i.e., the overhead of key generation is independent of the size of a total group. We support the proposed scheme with formal security proof. Namely, our proposed scheme is the first constant-round password-based group key exchange with different passwords for the dynamic setting of MANET. Keywords: Password authentication, key agreement, authenticated key exchange, heterogeneous, pervasive computing, multi-layer ad-hoc network. [ABSTRACT FROM AUTHOR]

It is technically feasible for mobile social software such as pairing or ‘matchmaking' systems to introduce people to others and assist information exchange. However, little is known about the social structure of many mobile communities or why they would want such pairing systems. While engaged in other work determining requirements for a mobile travel assistant we saw a potentially useful application for a pairing system to facilitate the exchange of travel information between backpackers. To explore this area, we designed two studies involving usage of a low-fidelity role prototype of a social pairing system for backpackers. Backpackers rated the utility of different pairing types, and provided feedback on the social implications of being paired based on travel histories. Practical usage of the social network pairing activity and the implications of broader societal usage are discussed. [ABSTRACT FROM AUTHOR]

In May 2005 Nokia Sensor application (www.nokia.com/sensor) was launched, allowing mobile phone users to create digital identity expressions, seen by other users within Bluetooth range. This paper describes the design and mass-scale longitudinal field trial of a precursor prototype called DigiDress. 618 participants voluntarily used the application for an average of 25 days. The identity expressions created were both serious and playful, revealing and non-revealing. Factors influencing the identity expression included strategies for personal impression management, privacy concerns, and social feedback. The application was used with both acquainted and unacquainted people, and viewing the identity expression of people nearby was one major motivation for continued use. Direct communication features such as Bluetooth messages were not commonly adopted. DigiDress acted as a facilitator for 'real' social interaction between previously unacquainted users. Privacy concerns and their alleviations, as well as use barriers, were identified. [ABSTRACT FROM AUTHOR]

Building capture and access (C&A) applications for use in the operation theatre differs greatly from C&A applications built to support other settings e.g. meeting rooms or classrooms. Based on field studies of surgical operations, this paper explores how to design C&A applications for the operation theatre. Based on the findings from our field work, we have built the ActiveTheatre, a C&A prototype. ActiveTheatre is built to support collaboration in and around the operating theatre, to capture events instead of automatically capturing everything, and to be integrated with existing applications already present in the operation theatre. The ActiveTheatre prototype has been developed in close co-operation with surgeons and nurses at a local hospital. The work on the prototype and our initial evaluations have provided an insight into how to design, capture and access applications that are going to be used in other settings than the meeting room. [ABSTRACT FROM AUTHOR]

This paper presents Treasure, an outdoor mobile multiplayer game inspired by Weiser's notion of seams, gaps and breaks in different media. Playing Treasure involves movement in and out of a wi-fi network, using PDAs to pick up virtual 'coins' that may be scattered outside network coverage. Coins have to be uploaded to a server to gain game points, and players can collaborate with teammates to double the points given for an upload. Players can also steal coins from opponents. As they move around, players' PDAs sample network signal strength and update coverage maps. Reporting on a study of players taking part in multiple games, we discuss how their tactics and strategies developed as their experience grew with successive games. We suggest that meaningful play arises in just this way, and that repeated play is vital when evaluating such games. [ABSTRACT FROM AUTHOR]

A frameless display is a display with no perceptible boundaries; it appears to be embodied in the physical world. Frameless displays are created by projecting visual elements on a black background into a physical environment. By considering visual arts and design theory together with our own experience building about a dozen applications, we argue the importance of this technique in creating ubiquitous computer applications that are truly contextualized in the physical world. Nine different examples using frameless displays are described, providing the background for a systematization of frameless displays pros and cons, together with a basic set of usage guidelines. The paper also discusses the differences and constraints on user interaction with visual elements in a frameless display. [ABSTRACT FROM AUTHOR]

Our goal in this paper is to clearly delineate how households currently manage communication and coordination information; this will provide practitioners and designers with a more complete view of information in the home, and how technology embedded within the home can augment communication and coordination of home inhabitants. Through contextual interviews, we identify five types of communicative information: reminders and alerts, awareness and scheduling, notices, visual displays, and resource coordination. These information types are created and understood by home inhabitants as a function of contextual locations within the home. The choice of location is important to the functioning of the home, and is highly nuanced. Location helps home inhabitants understand time: when others need to interact with that information, as well as ownership: who this information belongs to and who should receive it. It also provides them with awareness of the actions and locations of others. These findings resonate and further elaborate on work by other researchers. [ABSTRACT FROM AUTHOR]

Accurate indoor localization has long been an objective of the ubiquitous computing research community, and numerous indoor localization solutions based on 802.11, Bluetooth, ultrasound and infrared technologies have been proposed. This paper presents the first accurate GSM indoor localization system that achieves median accuracy of 5 meters in large multi-floor buildings. The key idea that makes accurate GSM-based indoor localization possible is the use of wide signal-strength fingerprints. In addition to the 6-strongest cells traditionally used in the GSM standard, the wide fingerprint includes readings from additional cells that are strong enough to be detected, but too weak to be used for efficient communication. Experiments conducted on three multi-floor buildings show that our system achieves accuracy comparable to an 802.11-based implementation, and can accurately differentiate between floors in both wooden and steel-reinforced concrete structures. [ABSTRACT FROM AUTHOR]

The ubiquitous computing community has widely researched the use of 802.11 for the purpose of location inference. Meanwhile, Bluetooth is increasingly widely deployed due to its low power consumption and cost. This paper describes a study of Bluetooth radio propagation using an accurate indoor location system to conduct fine-grained signal strength surveys. We discuss practical problems and requirements encountered setting up the infrastructure using the ultrasonic Active Bat indoor location system, and limitations of the commodity Bluetooth devices used. We conclude that Bluetooth is poorly suited to the purpose of fine-grained, low latency location inference due to specification and hardware limitations, and note that the movement speed of mobile devices is an important factor in calculating available bandwidth. We publish our data sets of signal strength samples for the community to freely use in future research. [ABSTRACT FROM AUTHOR]

Location systems that are based on scanning for nearby radio sources can estimate the position of a mobile device with reasonable accuracy and high coverage. These systems require a calibration step in which a map is built from radio-readings taken on a location-aware device. War driving, for example, calibrates the positions of WiFi access points using a GPS-equipped laptop. In this paper we introduce an algorithm for self-mapping that minimizes or even eliminates explicit calibration by allowing the location system to build this radio map as the system is used. Using nearly 100 days of trace data, we evaluate self-mapping's accuracy when the map is seeded by three realistic data sources: public war-driving databases, WiFi hotspot finders, and sporadic GPS connectivity. On average, accuracy and coverage are shown to be comparable to those achieved with an explicit war-driven radio map. [ABSTRACT FROM AUTHOR]

We present Supple, a novel toolkit which automatically generates interfaces for ubiquitous applications. Designers need only specify declarative models of the interface and desired hardware device and Supple uses decision-theoretic optimization to automatically generate a concrete rendering for that device. This paper provides an overview of our system and describes key extensions that barred the previous version (reported in [3]) from practical application. Specifically, we describe a functional modeling language capable of representing complex applications. We propose a new adaptation strategy, split interfaces, which speeds access to common interface features without disorienting the user. We present a customization facility that allows designers and end users to override Supple's automatic rendering decisions. We describe a distributed architecture which enables computationally-impoverished devices to benefit from Supple interfaces. Finally, we present experiments and a preliminary user-study that demonstrate the practicality of our approach. [ABSTRACT FROM AUTHOR]

This paper introduces a novel way to allow non-expert users to create smart surroundings. Non-smart everyday objects such as furniture and appliances found in homes and offices can be converted to smart ones by attaching computers, sensors, and devices. In this way, non-smart components that form non-smart objects are made smart in advance. For our first prototype, we have developed u-Texture, a self-organizable universal panel that works as a building block. The u-Texture can change its own behavior autonomously through recognition of its location, its inclination, and surrounding environment by assembling these factors physically. We have demonstrated several applications to confirm that u-Textures can create smart surroundings easily without expert users. [ABSTRACT FROM AUTHOR]

Alice first meets Bob in an entertainment shop, then, they wish to share multimedia content, but Do they know what are trustworthy users? How do they share such information in a secure way? How do they establish the permissions? Pervasive computing environments originate this kind of scenario, users with their personal devices interacting without need of wires, by forming ad-hoc networks. Such devices considered pervasive are having increasingly faster processors, larger memories and wider communication capabilities, which allows certain autonomy for collaborating and sharing resources. So, they require a suitable access control in order to avoid unauthorised access, or disclosure/modification of relevant information; in general, to protect the data that are usually confidential and the resources. This paper presents a distributed solution for access control, making use of the autonomy and cooperation capability of the devices, since in open dynamic environments is very difficult to depend on central server. The access control is based on a pervasive trust management model from which trust degrees are dynamically obtained. We present the TrustAC reference and functional model, as well as a prototype implementation using XACML-compliant policies. [ABSTRACT FROM AUTHOR]

We previously developed building blocks to enable end-users to construct customized sensor-based embedded systems to help monitor and control a users' environment. Because design objectives, like battery lifetime, reliability, and responsiveness, vary across applications, these building blocks have software-configurable parameters that control features like operating voltage, frequency, and communication baud rate. The parameters enable the same blocks to be used in diverse applications, in turn enabling mass-produced and hence low-cost blocks. However, tuning block parameters to an application is hard. We thus present an automated approach, wherein an end-user simply defines objectives using an intuitive graphical method, and our tool automatically tunes the parameter values to those objectives. The automated tuning improved satisfaction of design objectives, compared to a default general-purpose block configuration, by 40% on average, and by as much as 80%. The tuning required only 10-20 minutes of end-user time for each application. [ABSTRACT FROM AUTHOR]

Using existing communications infrastructure, such as 802.11 and GSM, researchers have demonstrated effective indoor localization. Inspired by these previous approaches, and recognizing some limitations of relying on infrastructure users do not control, we present an indoor location system that uses an even more ubiquitous domestic infrastructure—the residential powerline. PowerLine Positioning (PLP) is an inexpensive technique that uses fingerprinting of multiple tones transmitted along the powerline to achieve sub-room-level localization. We describe the basics behind PLP and demonstrate how it compares favorably to other fingerprinting techniques. [ABSTRACT FROM AUTHOR]

The pervasive nature of multimedia recording devices enables novel pervasive multimedia applications with automatic, inexpensive, and ubiquitous identification and locationing abilities. We present the design and implementation of Ferret, a scalable system for locating nomadic objects augmented with RFID tags and displaying them to a user in real-time. We present two alternative algorithms for refining a postulation of an object's location using a stream of noisy readings from an RFID reader: an online algorithm for real-time use on a mobile device, and an offline algorithm for use in post-processing applications. We also present methods for detecting when nomadic objects move and how to reset the algorithms to restart the refinement process. An experimental evaluation of the Ferret prototype shows that (i) Ferret can refine object locations to only 1% of the reader's coverage region in less than 2 minutes with small error rate (2.22%); (ii) Ferret can detect nomadic objects with 100% accuracy when the nomadic distances exceed 20cm; and (iii) Ferret works with a variety of user mobility patterns. [ABSTRACT FROM AUTHOR]

A sedentary lifestyle is a contributing factor to chronic diseases, and it is often correlated with obesity. To promote an increase in physical activity, we created a social computer game, Fish'n'Steps, which links a player's daily foot step count to the growth and activity of an animated virtual character, a fish in a fish tank. As further encouragement, some of the players' fish tanks included other players' fish, thereby creating an environment of both cooperation and competition. In a fourteen-week study with nineteen participants, the game served as a catalyst for promoting exercise and for improving game players' attitudes towards physical activity. Furthermore, although most player's enthusiasm in the game decreased after the game's first two weeks, analyzing the results using Prochaska's Transtheoretical Model of Behavioral Change suggests that individuals had, by that time, established new routines that led to healthier patterns of physical activity in their daily lives. Lessons learned from this study underscore the value of such games to encourage rather than provide negative reinforcement, especially when individuals are not meeting their own expectations, to foster long-term behavioral change. [ABSTRACT FROM AUTHOR]

We approach the design of ubiquitous computing systems in the urban environment as integral to urban design. To understand the city as a system encompassing physical and digital forms and their relationships with people's behaviours, we are developing, applying and refining methods of observing, recording, modelling and analysing the city, physically, digitally and socially. We draw on established methods used in the space syntax approach to urban design. Here we describe how we have combined scanning for discoverable Bluetooth devices with two such methods, gatecounts and static snapshots. We report our experiences in developing, field testing and refining these augmented methods. We present initial findings on the Bluetooth landscape in a city in terms of patterns of Bluetooth presence and Bluetooth naming practices. [ABSTRACT FROM AUTHOR]

Hitchers is a game for mobile phones that exploits cellular positioning to support location-based play. Players create digital hitch hikers, giving them names, destinations and questions to ask other players, and then drop them into their current phone cell. Players then search their current cell for hitchers, pick them up, answer their questions, carry them to new locations and drop them again, providing location-labels as hint to where they can be found. In this way, hitchers pass from player to player, phone to phone and cell to cell, gathering information and encouraging players to label cells with meaningful place names. A formative study of Hitchers played by 47 players over 4 months shows how the seams in cellular positioning, including varying cell size, density and overlap, affected the experience. Building on previous discussions of designing for uncertainty and seamful design, we consider five ways of dealing with these seams: removing, hiding, managing, revealing and exploiting them. This leads us to propose the mechanism of a dynamic search focus, to explore new visualization tools for cellular data, and to reconsider the general relationship between ‘virtual' and ‘physical' worlds in location-based games. Keywords: Mobile games, cellular positioning, ubiquitous computing, seamful design. [ABSTRACT FROM AUTHOR]

We describe a set of fixed-function and programmable blocks, eBlocks, previously developed to provide non-programming, non-electronics experts the ability to construct and customize basic embedded computing systems. We present a novel and powerful tool that, combined with these building blocks, enables end-users to automatically generate an optimized physical implementation derived from a virtual system function description. Furthermore, the tool allows the end-user to specify optimization criteria and constraint libraries that guide the tool in generating a suitable physical implementation, without requiring the end-user to have prior programming or electronics experience. We summarize experiments illustrating the ability of the tool to generate physical implementations corresponding to various end-user defined goals. The tool enables end-users having little or no electronics or programming experience to build useful customized basic sensor-based computing systems from existing low-cost building blocks. [ABSTRACT FROM AUTHOR]

Implicit in much research and application development for mobile phones is the assumption that the mobile phone is a suitable proxy for its owner's location. We report an in-depth empirical investigation of this assumption in which we measured proximity of the phone to its owner over several weeks of continual observation. Our findings, summarizing results over 16 different subjects of a variety of ages and occupations, establish baseline statistics for the proximity relationship in a typical US metropolitan market. Supplemental interviews help us to establish reasons why the phone and owner are separated, leading to guidelines for developing mobile phone applications that can be smart with respect to the proximity assumption. We show it is possible to predict the proximity relationship with 86% confidence using simple parameters of the phone, such as current cell ID, current date and time, signal status, charger status and ring/vibrate mode. [ABSTRACT FROM AUTHOR]

In current authoring tools for location-aware applications the designer typically places trigger zones onto a map of the target environment and associates these with events and media assets. However, studies of deployed experiences have shown that the characteristics of the usually invisible ubiquitous computing infrastructure, especially limited coverage and accuracy, have a major impact on an experience. We propose a new approach in which designers work with three layers of information: information about the physical world, information about digital media, but also visualizations of ubiquitous infrastructure. We describe the implementation of a prototype authoring tool that embodies this approach and describe how it has been used to author a location-based game for mobile phones called Tycoon. We then outline the key challenges involved in generalizing this approach to more powerful authoring tools including acquiring and visualizing infrastructure data, acquiring map data, and flexibly specifying how digital content relates to both of these. [ABSTRACT FROM AUTHOR]

Increasing availability of sensor-based location traces for individuals, combined with the goal of better understanding user context, has resulted in a recent emphasis on algorithms for automatically extracting users' significant places from location data. Place-finding can be characterized by two sub-problems, (1) finding significant locations, and (2) assigning semantic labels to those locations (the problem of "moving from location to place") [8]. Existing algorithms focus on the first sub-problem and on finding city-level locations. We use a principled approach in adapting Gaussian Mixture Models (GMMs) to provide a first solution for finding significant places within the home, based on the first set of long-term, precise location data collected from several homes. We also present a novel metric for quantifying the similarity between places, which has the potential to assign semantic labels to places by comparing them to a library of known places. We discuss several implications of these new techniques for the design of Ubicomp systems. [ABSTRACT FROM AUTHOR]