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Proceedings of Pervasive 2007: International Conference on Pervasive Computing

Fullname:Pervasive 2007: Pervasive Computing, 5th International Conference
Editors:Anthony LaMarca; Marc Langheinrich; Khai N. Truong
Location:Toronto, Canada
Dates:2007-May-13 to 2007-May-16
Series:Lecture Notes in Computer Science 4480 Springer 2007
Standard No:ISBN 978-3-540-72036-2; hcibib: Pervasive07
Links:Online Proceedings
  1. Reaching Out
  2. Context and Its Application
  3. Security and Privacy
  4. Understanding Use
  5. Sensing
  6. Finding and Positioning

Reaching Out

Augmenting Looking, Pointing and Reaching Gestures to Enhance the Searching and Browsing of Physical Objects BIBAFull-Text 1-18
  David Merrill; Pattie Maes
In this paper we present a framework for attaching information to physical objects in a way that can be interactively browsed and searched in a hands-free, multi-modal, and personalized manner that leverages users' natural looking, pointing and reaching behaviors. The system uses small infrared transponders on objects in the environment and worn by the user to achieve dense, on-object visual feedback usually possible only in augmented reality systems, while improving on interaction style and requirements for wearable gear. We discuss two applications that have been implemented, a tutorial about the parts of an automobile engine and a personalized supermarket assistant. The paper continues with a user study investigating browsing and searching behaviors in the supermarket scenario, and concludes with a discussion of findings and future work.
Reach Out and Touch: Using NFC and 2D Barcodes for Service Discovery and Interaction with Mobile Devices BIBAFull-Text 19-36
  Eamonn O'Neill; Peter Thompson; Stavros Garzonis; Andrew Warr
We investigate the use of 2 tagging technologies: Near Field Communication (NFC) and 2-dimensional barcodes. Our investigation combined a field trial and interview based study with an experimental evaluation. The field trial focused on users' experience of the usability of NFC for a range of trial services, users' perceptions of NFC use in their daily life context, and users' suggestions for potential applications of NFC. The tags were embedded in a variety of postcards, table-top signs and posters. The experimental evaluation compared the ease of use of NFC and 2D barcodes, operationalised in terms of time taken to read a specified sequence of tags on posters. We found that for untrained users the 2D barcodes were quicker to use than the NFC tags but that training significantly improved users' performance with the NFC tags while having no effect on their performance with the barcodes.
Combining Web, Mobile Phones and Public Displays in Large-Scale: Manhattan Story Mashup BIBAFull-Text 37-54
  Ville H. Tuulos; Jürgen Scheible; Heli Nyholm
We present a large-scale pervasive game called Manhattan Story Mashup that combines the Web, camera phones, and a large public display. The game introduces a new form of interactive storytelling which lets an unlimited number of players author stories in the Web while a large number of players illustrate the stories with camera phones. This paper presents the first deployment of the game and a detailed analysis of its quantitative and qualitative results. We present details on the game implementation and game set up including practical lessons learnt about this large-scale experiment involving over 300 players in total. The analysis shows how the game succeeds in fostering players' creativity by exploiting ambiguity and how the players were engaged in a fast-paced competition which resulted in 115 stories and 3142 photos in 1.5 hours.

Context and Its Application

PersonisAD: Distributed, Active, Scrutable Model Framework for Context-Aware Services BIBAFull-Text 55-72
  Mark Assad; David J. Carmichael; Judy Kay; Bob Kummerfeld
PersonisAD, is a framework for building context-aware, ubiquitous applications: its defining foundation is a consistent mechanism for scrutable modelling of people, sensors, devices and places. This paper describes the PersonisAD features for supporting distributed models with active elements which can trigger when relevant events occur. This framework makes it possible to quickly create new context-aware applications. We demonstrate the power of the framework by describing how it has been used to create two context aware applications: MusicMix which plays music based on the preferences of the people in the room; MyPlace, which informs people of relevant details of the current environment. Major contributions of this work are: the PersonisAD framework which provides a powerful and consistent means to respond to significant changes in the models of people, sensors, devices and places; support for distributed models and associated resource discovery; two applications that illustrate the power of PersonisAD.
An Exploration into Activity-Informed Physical Advertising Using PEST BIBAKFull-Text 73-90
  Matthias C. Sala; Kurt Partridge; Linda Jacobson; James Begole
Targeted advertising benefits consumers by delivering them only the messages that match their interests, and also helps advertisers by identifying only the consumers interested in their messages. Although targeting mechanisms for online advertising are well established, pervasive computing environments lack analogous approaches. This paper explores the application of activity inferencing to targeted advertising. We present two mechanisms that link activity descriptions with ad content: direct keyword matching using an online advertising service, and "human computation" matching, which enhances keyword matching with help from online workers. The direct keyword approach is easier to engineer and responds more quickly, whereas the human computation approach has the potential to target more effectively.
Keywords: Ubiquitous computing; experience sampling method; human computation; advertising.
Evaluating a Wearable Display Jersey for Augmenting Team Sports Awareness BIBAKFull-Text 91-108
  Mitchell Page; Andrew Vande Moere
This paper introduces a user-centered design process and case study evaluation of a novel wearable visualization system for team sports, coined TeamAwear. TeamAwear consists of three basketball jerseys that are equipped with electroluminescent wires and surfaces. Each jersey can be wirelessly controlled to represent game-related information on the player in real-time, such as the amount of individual fouls, scores and time alerts. A participatory user-centered approach guided the development process towards a more meaningful, ethically and ergonomically valid design. The system aims to enhance the awareness and understanding of game-related public information for all stakeholders, including players, referees, coaches and audience members. We initially hypothesized that such increased awareness would positively influence in-game decisions by players, resulting in a more interesting and enjoyable game play experience for all participants. Instead, the case study evaluation demonstrated TeamAwear's perceived usefulness particularly for non-playing stakeholders, such as the audience, referees and coaches, supporting more accurate coaching assessments, better understanding of in-game situations and increased enjoyment for spectators. The high amount of game-related cognitive load on the players during game-play seems to hinder its influence on in-game decisions.
Keywords: wearable computing; visualization; design; evaluation
Using Location, Bearing and Motion Data to Filter Video and System Logs BIBAKFull-Text 109-126
  Alistair Morrison; Paul Tennent; John Williamson; Matthew Chalmers
In evaluating and analysing a pervasive computing system, it is common to log system use and to create video recordings of users. A lot of data will often be generated, representing potentially long periods of user activity. We present a procedure to identify sections of such data that are salient given the current context of analysis; for example analysing the activity of a particular person among many trial participants recorded by multiple cameras. By augmenting the cameras used to capture a mobile experiment, we are able to establish both a location and heading for each camera, and thus model the field of view for each camera over time. Locations of trial participants are also recorded and compared against camera views, to determine which periods of user activity are likely to have been recorded in detail. Additionally the stability of a camera can be tracked and video can be subsequently filtered to exclude footage of unacceptable quality. These techniques are implemented in an extension to Replayer: a software toolkit for use in the development cycle of mobile applications. A report of initial testing is given, whereby the technique's use is demonstrated on a representative mobile application.
Keywords: Video; auto-classification; analysis toolkit; log synchronisation; visualisation

Security and Privacy

Inference Attacks on Location Tracks BIBAKFull-Text 127-143
  John Krumm
Although the privacy threats and countermeasures associated with location data are well known, there has not been a thorough experiment to assess the effectiveness of either. We examine location data gathered from volunteer subjects to quantify how well four different algorithms can identify the subjects' home locations and then their identities using a freely available, programmable Web search engine. Our procedure can identify at least a small fraction of the subjects and a larger fraction of their home addresses. We then apply three different obscuration countermeasures designed to foil the privacy attacks: spatial cloaking, noise, and rounding. We show how much obscuration is necessary to maintain the privacy of all the subjects.
Keywords: location; privacy; inference attack; location tracks
Shake Well Before Use: Authentication Based on Accelerometer Data BIBAFull-Text 144-161
  Rene Mayrhofer; Hans Gellersen
Small, mobile devices without user interfaces, such as Bluetooth headsets, often need to communicate securely over wireless networks. Active attacks can only be prevented by authenticating wireless communication, which is problematic when devices do not have any a priori information about each other. We introduce a new method for device-to-device authentication by shaking devices together. This paper describes two protocols for combining cryptographic authentication techniques with known methods of accelerometer data analysis to the effect of generating authenticated, secret keys. The protocols differ in their design, one being more conservative from a security point of view, while the other allows more dynamic interactions. Three experiments are used to optimize and validate our proposed authentication method.
Virtual Walls: Protecting Digital Privacy in Pervasive Environments BIBAFull-Text 162-179
  Apu Kapadia; Tristan Henderson; Jeffrey J. Fielding; David Kotz
As pervasive environments become more commonplace, the privacy of users is placed at increased risk. The numerous and diverse sensors in these environments can record users' contextual information, leading to users unwittingly leaving "digital footprints." Users must thus be allowed to control how their digital footprints are reported to third parties. While a significant amount of prior work has focused on location privacy, location is only one type of footprint, and we expect most users to be incapable of specifying fine-grained policies for a multitude of footprints. In this paper we present a policy language based on the metaphor of physical walls, and posit that users will find this abstraction to be an intuitive way to control access to their digital footprints. For example, users understand the privacy implications of meeting in a room enclosed by physical walls. By allowing users to deploy "virtual walls," they can control the privacy of their digital footprints much in the same way they control their privacy in the physical world. We present a policy framework and model for virtual walls with three levels of transparency that correspond to intuitive levels of privacy, and the results of a user study that indicates that our model is easy to understand and use.
Trust, Privacy and Relationships in 'Pervasive Education': Families' Views on Homework and Technologies BIBAFull-Text 180-197
  Katie Fraser; Tom Rodden; Claire O'Malley
Extensive educational research discusses the potential for information and communication technologies in supporting homework, but most has focused on providing content. The research in this paper focuses instead on the issues around managing homework and balancing home and school through the capabilities of ubiquitous technologies. As part of our requirements capture we presented three families with demonstrators of ubiquitous computing systems. Our technologies provoked reactions to situated and embedded information capture and access, and locational information capture through mobile devices. The subtlety and complexity of roles and relationships of different family members raised issues around trust and privacy in relation to children's homework practices. We consider how these drove acceptance of the technologies, and how the contrasts between family and educational relationships produced different requirements for technologies managing information transfer inside and outside the home. Overall, we highlight how respect for these concerns can inform the design of pervasive technologies, particularly within the domestic and educational contexts bridged.

Understanding Use

Operating Appliances with Mobile Phones -- Strengths and Limits of a Universal Interaction Device BIBAFull-Text 198-215
  Christof Roduner; Marc Langheinrich; Christian Floerkemeier; Beat Schwarzentrub
Mobile phones are increasingly becoming ubiquitous computational devices that are almost always available, individually adaptable, and nearly universally connectable (using both wide area and short range communication capabilities). Until Star Trek-like speech interfaces are fully developed, mobile phones seem thus poised to become our main devices for interacting with intelligent spaces and smart appliances, such as buying train passes, operating vending machines, or controlling smart homes (e.g., TVs, stereos, and dishwashers, as well as heating and light). But how much can a mobile phone simplify our everyday interactions, before it itself becomes a usability burden? What are the capabilities and limitations of using mobile phones to control smart appliances, i.e., operating things like ATMs or coffee makers that typically do not benefit from remote control? This paper presents a user study investigating the use of a prototypical, mobile phone based interaction system to operate a range of appliances in a number of different task settings. Our results show that mobile devices can greatly simplify appliance operation in exceptional situations, but that the idea of a universal interaction device is less suited for general, everyday appliance control.
Portable, But Not Mobile: A Study of Wireless Laptops in the Home BIBAFull-Text 216-233
  Allison Woodruff; Ken Anderson; Scott D. Mainwaring; Ryan Aipperspach
We report a qualitative study of the use of physical space and wireless laptops by ten United States households. Although wireless laptops purportedly offer the opportunity and affordances to go "anywhere in the home," laptops were generally used in a small set of particular places rather than moving fluidly through the home: wireless laptops were portable, but not mobile per se We present factors that influence laptop movement in the home. We also present a model of people's use of space in the home, identifying a small set of favored places of long-term use and a larger set of kinetic places used for specific tasks. We discuss how the factors we have identified generally promote use of laptops in favored places and generally discourage use of laptops in kinetic places. We discuss how our findings are relevant to the design of technologies for the home.
Managing Communication Availability and Interruptions: A Study of Mobile Communication in an Oncology Department BIBAFull-Text 234-250
  Jeremiah Scholl; Per Hasvold; Eva Henriksen; Gunnar Ellingsen
Wireless phones and text messaging are tremendously popular in many areas of society. However, they are still relatively unused in hospitals where pagers are a pervasive communication device that is notoriously difficult to replace. This paper studies pager and wireless phone use at the oncology department at University Hospital of North Norway. Participatory observation and interviews with physicians are used to provide qualitative analysis about the use, drawbacks and benefits of both technologies. A number of important issues are addressed that should aid designers of next generation mobile communication systems for hospitals. In particular, the data points towards specific features that will be crucial for the overall usability and acceptance of an integrated device that supports paging, voice and text services. Of particular importance will be features that allow users to manage their communication availability and avoid interruptions.


Using Ground Reaction Forces from Gait Analysis: Body Mass as a Weak Biometric BIBAKFull-Text 251-267
  Jam Jenkins; Carla Schlatter Ellis
Ground reaction forces generated during normal walking have recently been used to identify and/or classify individuals based upon the pattern of the forces observed over time. One feature that can be extracted from vertical ground reaction forces is body mass. This single feature has identifying power comparable to other studies that use multiple and more complex features. This study contributes to understanding the role of body mass in identification by (1) quantifying the accuracy and precision with which body mass can be obtained using vertical ground reaction forces, (2) quantifying the distribution of body mass across a population larger than has previously been studied in relation to gait analysis, and (3) quantifying the expected identification capabilities of systems using body mass as a weak biometric. Our results show that body mass can be measured in a fraction of a second with less than a 1 kilogram standard deviation of error.
Keywords: body mass; biometric; ground reaction forces; gait
Weight-Sensitive Foam to Monitor Product Availability on Retail Shelves BIBAKFull-Text 268-279
  Christian Metzger; Jan Meyer; Elgar Fleisch; Gerhard Tröster
The retail industry, which is characterized by highly complex supply chain processes, still faces stockout rates of 5-10%. This results in sales losses of up to 4% which corresponds to hundreds of millions of dollars for large retailers. The most significant cause for stockout situations is inefficiencies in in-store logistics due to the lack of inventory visibility. In this paper, we present a product availability monitoring system, which anticipates stockouts before they occur and triggers the personnel to replenish the shelf. Our monitoring system is based on inexpensive polyolefin foam, which serves as mount for capacitive sensing elements. Our sensor system is designed for roll-to-roll based manufacturing, which suggests low production costs. Preliminary tests suggest that the system offers sufficient sensitivity to accurately and reliably detect low quantities of stocks. This will not only reduce losses of sales but also increase customer satisfaction.
Keywords: Retail logistics; shelf replenishment; product availability monitoring; capacitive sensors; pervasive computing
Assessing and Optimizing the Range of UHF RFID to Enable Real-World Pervasive Computing Applications BIBAFull-Text 280-297
  Steve Hodges; Alan Thorne; Hugo Mallinson; Christian Floerkemeier
Radio frequency identification (RFID) may be used to automatically detect, locate and/or identify objects, making it an ideal candidate for many pervasive computing applications. As RFID technology improves in terms of cost and performance, it is increasingly being explored in a variety of applications, ranging from eldercare through to the smart supply chain. However, while passive UHF RFID has many benefits over other RFID variants, reliable operation as the tag moves in the environment is inherently difficult to predict and can represent a significant challenge. In this paper, we present a novel and practical experimental method called attenuation-thresholding which may be used to characterize the operating range of such RFID systems. The results presented demonstrate the advantages of our method over the conventional read-rate approach. We also demonstrate a novel approach to collecting the measurements in range characterization experiments using robotic automation. Finally, we show how the application of attenuation-thresholding in combination with robotic automation can be used to optimize tag placement on an object. In addition to the clear relevance of this work to the many RFID-based pervasive computing applications reported in the literature and currently under development, it also has broad applicability in other RFID application domains. We conclude with a number of ideas for future extensions to this work.
Movement-Based Group Awareness with Wireless Sensor Networks BIBAFull-Text 298-315
  Raluca Marin-Perianu; Mihai Marin-Perianu; Paul J. M. Havinga; Hans Scholten
We propose a method through which dynamic sensor nodes determine that they move together by communicating and correlating their movement information. We describe two possible solutions, one using inexpensive tilt switches, and another one using low-cost MEMS accelerometers. We implement a fast, incremental correlation algorithm, which can run on resource constrained devices. The tests with the implementation on real sensor nodes show that the method distinguishes between joint and separate movements. In addition, we analyse the scalability from four different perspectives: communication, energy, memory and execution speed. The solution using tilt switches proves to be simpler, cheaper and more energy efficient, while the accelerometer-based solution is more accurate and more robust to sensor alignment problems.

Finding and Positioning

Zone-Based RSS Reporting for Location Fingerprinting BIBAFull-Text 316-333
  Mikkel Baun Kjærgaard; Georg Treu; Claudia Linnhoff-Popien
In typical location fingerprinting systems a tracked terminal reports sampled Received Signal Strength (RSS) values to a location server, which estimates its position based on a database of pre-recorded RSS fingerprints. So far, poll-based and periodic RSS reporting has been proposed. However, for supporting proactive Location-based Services (LBSs), triggered by pre-defined spatial events, the periodic protocol is inefficient. Hence, this paper introduces zone-based RSS reporting: the location server translates geographical zones defined by the LBS into RSS-based representations, which are dynamically configured with the terminal. The terminal, in turn, reports its measurements only when they match with the configured RSS patterns. As a result, the number of messages exchanged between terminal and server is strongly reduced, saving battery power, bandwidth and also monetary costs spent for mobile bearer services. The paper explores several methods for realizing zone-based RSS reporting and evaluates them simulatively and analytically. An adaption of classical Bayes estimation turns out to be the best suited method.
TrackSense: Infrastructure Free Precise Indoor Positioning Using Projected Patterns BIBAFull-Text 334-350
  Moritz Köhler; Shwetak N. Patel; Jay Summet; Erich P. Stuntebeck; Gregory D. Abowd
While commercial solutions for precise indoor positioning exist, they are costly and require installation of additional infrastructure, which limits opportunities for widespread adoption. Inspired by robotics techniques of Simultaneous Localization and Mapping (SLAM) and computer vision approaches using structured light patterns, we propose a self-contained solution to precise indoor positioning that requires no additional environmental infrastructure. Evaluation of our prototype, called TrackSense, indicates that such a system can deliver up to 4 cm accuracy with 3 cm precision in rooms up to five meters squared, as well as 2 degree accuracy and 1 degree precision on orientation. We explain the design and performance characteristics of our prototype and demonstrate a feasible miniaturization that supports applications that require a single device localizing itself in a space. We also discuss extensions to locate multiple devices and limitations of this approach.
Objects Calling Home: Locating Objects Using Mobile Phones BIBAFull-Text 351-368
  Christian Frank; Philipp Bolliger; Christof Roduner; Wolfgang Kellerer
Locating physical items is a highly relevant application addressed by numerous systems. Many of these systems share the drawback that costly infrastructure must be installed before a significant physical area can be covered, that is, before these systems may be used in practice. In this paper, we build on the ubiquitous infrastructure provided by the mobile phone network to design a wide-area system for locating objects. Sensor-equipped mobile phones, naturally omnipresent in populated environments, are the main elements of our system. They are used to distribute search queries and to report an object's location. We present the design of our object search system together with a set of simple heuristics which can be used for efficient object search. Moreover, such a system can only be successfully deployed if environment conditions (such as the participant density and their mobility) and system settings (such as number of queried sensors) allow to find an object quickly and efficiently. We therefore demonstrate the practicability of our system and obtain suitable system parameters for its execution in a series of simulations. Further, we use a real-world experiment to validate the obtained simulation results.