Cost and accessibility have impeded the adoption of spirometers (devices that measure lung function) outside clinical settings, especially in low-resource environments. Prior work, called SpiroSmart, used a smartphone's built-in microphone as a spirometer. However, individuals in low- or middle-income countries do not typically have access to the latest smartphones. In this paper, we investigate how spirometry can be performed from any phone-using the standard telephony voice channel to transmit the sound of the spirometry effort. We also investigate how using a 3D printed vortex whistle can affect the accuracy of common spirometry measures and mitigate usability challenges. Our system, coined SpiroCall, was evaluated with 50 participants against two gold standard medical spirometers. We conclude that SpiroCall has an acceptable mean error with or without a whistle for performing spirometry, and advantages of each are discussed.

Accredited Social Health Activists (ASHAs) have been shown to have a positive impact on health outcomes of the households they visit, particularly in maternal and neonatal health. As the first line of the public health system in many countries, they are a critical link to the broader public health infrastructure for community members. Yet they do this all with minimal training and limited support infrastructure. To a pregnant woman, an ASHA is a trusted ally in navigating the health system---information gathered is returned by appropriate advice and counseling. To the health system, the ASHA is a key channel of valuable householdlevel information for the public health system, yet she generally receives minimal guidance in return. In this paper we present ASTA---the ASHA Self-Tracking Application---a system that provides ASHAs with timely, on-demand information regarding their own performance compared to their peers. Using ASTA, ASHAs access comparative performance data through both a web-based and voice-based interface on demand. We evaluated ASTA through a 12-month deployment with 142 ASHAs in Uttar Pradesh, India, assessing the impact of providing feedback on ASHA performance. We find that ASHAs with access to the ASTA system made significantly more client visits, with average monthly visits 21.5% higher than ASHAs who had access to a control system. In addition, higher ASHA performance was correlated with increased usage of ASTA. However, the performance improvement was front-loaded, with the impact of the system decreasing toward the end of the study period. Taken together, our findings provide promising evidence that studying and incorporating tools like ASTA could be cost effective and impactful for ASHA programs.

Interactive voice forums have emerged as a promising platform for people in developing regions to record and share audio messages using low-end mobile phones. However, one of the barriers to the scalability of voice forums is the process of screening and categorizing content, often done by a dedicated team of moderators. We present Sangeet Swara, a voice forum for songs and cultural content that relies on the community of callers to curate high-quality posts that are prioritized for playback to others. An 11-week deployment of Sangeet Swara found broad and impassioned usage, especially among visually impaired users. We also conducted a follow-up experiment, called Talent Hunt, that sought to reduce reliance on toll-free telephone lines. Together, our deployments span about 53,000 calls from 13,000 callers, who submitted 6,000 posts and 150,000 judgments of other content. Using a mixed-methods analysis of call logs, audio content, comparison with outside judges, and 204 automated phone surveys, we evaluate the user experience, the strengths and weaknesses of community moderation, financial sustainability, and the implications for future systems.

Global development organizations rely on the essential affordances provided by both paper and digital materials to navigate hurdles posed by poor infrastructure, low connectivity, linguistic differences, and other socioeconomic constraints that render communication and collaboration challenging. This paper examines the collaborative practices around paper-digital workflows within global development organizations operating in low-resource environments. We use a mixed methods approach to gather data from 23 organizations in 16 countries. Our findings show the tensions that arise between the ubiquitousness of paper and the desirability of digitized data, and highlight the challenges associated with transitioning information several times between paper and digital materials. We also reveal design opportunities for new tools to bridge the gap between paper-based and digital information in low-resource settings. Finally, we contribute a nuanced understanding of the cross-cultural and infrastructural challenges that influence the paper-digital lifecycle. Our findings will be useful for researchers and practitioners interested in understanding or participating in the workflows that drive global development.

Emerging uses of imaging technology for consumers cover a wide range of application areas from health to interaction techniques; however, typical cameras primarily transduce light from the visible spectrum into only three overlapping components of the spectrum: red, blue, and green. In contrast, hyperspectral imaging breaks down the electromagnetic spectrum into more narrow components and expands coverage beyond the visible spectrum. While hyperspectral imaging has proven useful as an industrial technology, its use as a sensing approach has been fragmented and largely neglected by the UbiComp community. We explore an approach to make hyperspectral imaging easier and bring it closer to the end-users. HyperCam provides a low-cost implementation of a multispectral camera and a software approach that automatically analyzes the scene and provides a user with an optimal set of images that try to capture the salient information of the scene. We present a number of use-cases that demonstrate HyperCam's usefulness and effectiveness.

We present SurfaceLink, a system where users can make natural surface gestures to control association and information transfer among a set of devices that are placed on a mutually shared surface (e.g., a table). SurfaceLink uses a combination of on-device accelerometers, vibration motors, speakers and microphones (and, optionally, an off-device contact microphone for greater sensitivity) to sense gestures performed on the shared surface. In a controlled evaluation with 10 participants, SurfaceLink detected the presence of devices on the same surface with 97.7% accuracy, their relative arrangement with 89.4% accuracy, and various single- and multi-touch surface gestures with an average accuracy of 90.3%. A usability analysis showed that SurfaceLink has advantages over current multi-device interaction techniques in a number of situations.

Since 2008, we have been applying smartphones and tablets to problems in the developing world in the domains of public health, environment monitoring, agriculture, and human rights monitoring (among others). The Open Data Kit (opendatakit.org) collection of modular tools for both client and server-side functions has been highly successful with tens of thousands of users in hundreds of organization on six continents. In this keynote, I will describe what we believe to be the principal features of this success, namely: (1) tackling real problems within a context of participatory design; (2) creating an open source community and ecosystem of companies around the tools; and (3) generalization of the modules so they can be easily adapted to different contexts. I will also argue that this line of problem-solving leads to explorations of different regions of the design space than would occur in the developed world due to the particular constraints that must be satisfied. Finally, I will conclude with some recommendations for the ubicomp community.

The worldwide adoption of mobile devices presents an opportunity to build mobile systems to support health workers in low-resource settings. This paper presents an in-depth field evaluation of a mobile system that uses a smartphone's built-in camera and computer vision to capture and analyze diagnostic tests for infectious diseases. We describe how health workers integrate the system into their daily clinical workflow and detail important differences in system usage between small clinics and large hospitals that could inform the design of future mobile health systems. We also describe a variety of strategies that health workers developed to overcome poor network connectivity and transmit data to a central database. Finally, we show strong agreement between our system's computed diagnoses and trained health workers' visual diagnoses, which suggests that our system could aid disease diagnosis in a variety of scenarios. Our findings will help to guide ministries of health and other stakeholders working to deploy mobile health systems in similar environments.

Mobile computing has deeply influenced the lives of almost every human in the world on a daily basis. In celebration of the 20th anniversary of Mobicom, Mobicom 2014 features an exciting panel on the topic of tackling societal grand challenges using mobile computing. The panel features five excellent researchers who have had a tremendous impact on the field of mobile computing over the years and whose research work has directly addressed pressing societal problems. The panel discussion will feature an in-depth discussion of the grand challenges that we face in society today and the role of mobile computing as a frontier platform for addressing these challenges. The panel will cover both a retrospective and futuristic perspective where the retrospective aspects highlight the diverse contributions of the panelists and the futuristic aspects will feature of a discussion of their individual views of what are the next big societal problems that Mobicom as a community should tackle.

Open Data Kit (ODK) is an open-source, modular toolkit that enables organizations to build application-specific mobile information services in resource-constrained environments. Feedback from users and developers about limitations experienced with the ODK 1.x set of tools led to a redesign of the system architecture and the creation of new tools. This demonstration presents a revised tool suite called ODK 2.0. This expanded ODK toolkit aims to increase an organization's data collection and management capabilities by supporting data synchronization, adaptable workflows, more configurable presentation screens, and increasing the diversity of input types by enabling new data input methods on mobile devices.

Mobile devices are integral to the workflows of many organizations working in rural or disconnected contexts. Data is often collected on mobile phones and tablets using tools like Open Data Kit (ODK). However, some of the applications require users to revisit and update previously collected data, necessitating easy viewing of stored data. To make it easier for organizations to create flexible information services, we present ODK Tables, an Android tool that allows users to enter and curate data on mobile devices. Tables leverages web tools to make mobile app creation simple. It provides abstractions to make the process straightforward and allows app designers to access data through a JavaScript API. App designers can create a custom app using only a small number of HTML and JavaScript files. This facilitates the creation of a custom user interface but leaves storage, data management, and synchronization to the framework. The result is a fully featured Android app based on established web-based tools with full support for disconnected operation.

Surveys conducted by human interviewers are one of the principal means of gathering data from all over the world, but the quality of this data can be threatened by interviewer fabrication. In this paper, we investigate a new approach to detecting interviewer fabrication automatically. We instrument electronic data collection software to record logs of low-level behavioral data and show that supervised classification, when applied to features extracted from these logs, can identify interviewer fabrication with an accuracy of up to 96%. We show that even when interviewers know that our approach is being used, have some knowledge of how it works, and are incentivized to avoid detection, it can still achieve an accuracy of 86%. We also demonstrate the robustness of our approach to a moderate amount of label noise and provide practical recommendations, based on empirical evidence, on how much data is needed for our approach to be effective.

We describe our experiences integrating ODK Scan into the community health worker (CHW) supply chain in Mozambique. ODK Scan is a mobile application that uses computer vision techniques to digitize data from paper forms. The application automatically classifies machine-readable data types, like bubbles and checkboxes, and assists users with the manual entry of handwritten text and numbers. We designed an intervention that uses paper forms in conjunction with ODK Scan to monitor CHW usage of essential health commodities, finding that the application is capable of providing supervisors and stakeholders with important information regarding health commodity availability in the field. Specifically, we (1) detail our experiences integrating ODK Scan into the health worker supply chain in Mozambique, with particular emphasis on the critical (and often under-reported) role of practitioners; (2) evaluate the impact of the technology at multiple levels of the information hierarchy, providing quantitative and qualitative data that exposes the benefits, challenges and limitations of the technology; and (3) share lessons learned and provide actionable guidance to researchers and practitioners interested in ODK Scan or other systems that bridge the gap between paper-based and digital data collection.

In this paper we describe three different offerings of a multi-quarter multidisciplinary capstone experience where students engaged in designing and building technology to address problems faced by populations in local and remote resource-constrained environments. We define resource-constrained environments broadly (e.g., low-income communities, low bandwidth environments). These environments provide unique constraints (e.g., cultures where people are unfamiliar with or afraid of technology, environments where power and network connectivity are scarce and expensive). Students are partnered with organizations interested in piloting a solution they devise. The course brings together multidisciplinary teams of students to conduct fieldwork with potential user populations, design a technology to solve a problem inspired by a community-based organization, implement a solution, and evaluate that solution. Students work on projects with real-world impact and gain valuable experience with multidisciplinary design and multidisciplinary team work. In this paper we describe the three class formats we have attempted, sample student projects, and course outcomes based on student projects and survey responses. We also address the various ways projects have continued past the course, and we analyze the structural course and project elements that have contributed to student and research successes.

Home spirometry is gaining acceptance in the medical community because of its ability to detect pulmonary exacerbations and improve outcomes of chronic lung ailments. However, cost and usability are significant barriers to its widespread adoption. To this end, we present SpiroSmart, a low-cost mobile phone application that performs spirometry sensing using the built-in microphone. We evaluate SpiroSmart on 52 subjects, showing that the mean error when compared to a clinical spirometer is 5.1% for common measures of lung function. Finally, we show that pulmonologists can use SpiroSmart to diagnose varying degrees of obstructive lung ailments.

While previous work has shown that clinical decision support systems (CDSS) improve patient care in resource-limited settings, there is little access to such systems at the point of care. Moreover, even when CDSS are available, compliance with care suggestions remain low. In this paper, we use a multi-method approach to document four failure modes that can affect CDSS implementations. Building from six iteratively derived design principles, we describe a phone-based system designed to address these failure modes. Through a formal usability evaluation, we discover six core findings that are important for implementers of mobile systems for health care providers in resource-limited settings.

Community health workers (CHWs) have been shown to be an effective and powerful intervention for improving community health. Routine visits, for example, can lower maternal and neonatal mortality rates. Despite these benefits, many challenges, including supervision and support, make CHW programs difficult to maintain. An increasing number of mHealth projects are providing CHWs with mobile phones to support their work, which opens up opportunities for real-time supervision of the program. Taking advantage of this potential, we evaluated the impact of SMS reminders to improve the promptness of routine CHW visits, first in a pilot study in Dodoma, Tanzania, followed by two larger studies with 87 CHWs in Dar es Salaam, Tanzania. The first Dar es Salaam study evaluated an escalating reminder system that sent SMS reminders directly to the CHW before notifying the CHW's supervisor after several overdue days. The reminders resulted in an 86% reduction in the average number of days a CHW's clients were overdue (9.7 to 1.4 days), with only a small number of cases ever escalating to the supervisor. However, when the step of escalating to the supervisor was removed in the second study, CHW performance significantly decreased.

Smartphones can now connect to a variety of external sensors over wired and wireless channels. However, ensuring proper device interaction can be burdensome, especially when a single application needs to integrate with a number of sensors using different communication channels and data formats. This paper presents a framework to simplify the interface between a variety of external sensors and consumer Android devices. The framework simplifies both application and driver development with abstractions that separate responsibilities between the user application, sensor framework, and device driver. These abstractions facilitate a componentized framework that allows developers to focus on writing minimal pieces of sensor-specific code enabling an ecosystem of reusable sensor drivers. The paper explores three alternative architectures for application-level drivers to understand trade-offs in performance, device portability, simplicity, and deployment ease. We explore these tradeoffs in the context of four sensing applications designed to support our work in the developing world. They highlight a range of sensor usage models for our application-level driver framework that vary data types, configuration methods, communication channels, and sampling rates to demonstrate the framework's effectiveness.

OBJECTIVE: In parts of the developing world traditionally modeled healthcare systems do not adequately meet the needs of the populace. This can be due to imbalances in both supply and demand--there may be a lack of sufficient healthcare and the population most at need may be unable or unwilling to take advantage of it. Home-based care has emerged as a possible mechanism to bring healthcare to the populace in a cost-effective, useful manner. This study describes the development, implementation, and evaluation of a mobile device-based system to support such services. MATERIALS AND METHODS: Mobile phones were utilized and a structured survey was implemented to be administered by community health workers using Open Data Kit. This system was used to support screening efforts for a population of two million persons in western Kenya. RESULTS: Users of the system felt it was easy to use and facilitated their work. The system was also more cost effective than pen and paper alternatives. DISCUSSION: This implementation is one of the largest applications of a system utilizing handheld devices for performing clinical care during home visits in a resource-constrained environment. Because the data were immediately available electronically, initial reports could be performed and important trends in data could thus be detected. This allowed adjustments to the programme to be made sooner than might have otherwise been possible. CONCLUSION: A viable, cost-effective solution at scale has been developed and implemented for collecting electronic data during household visits in a resource-constrained setting.

We present our experiences with an SMS-based system for providing transit information based solely on existing cellular and GPS networks. The aim is to permit the development of information services that do not rely on a central authority or complex web hosting. We developed and applied our system to the network of privately-run marshrutka buses in Bishkek, Kyrgyzstan. However, our goal is to more broadly address issues of ad-hoc shared transportation systems in the developing world. A custom designed GPS-GSM unit is placed on a vehicle, and users can query our server over SMS with their own non-GPS-enabled cell phones. We report on the accuracy of our location naming approach and estimates of bus arrival times. In addition, we summarize interviews with bus drivers and bus riders relating their views of the system and outline directions for future work. Our system is a grassroots solution to the persistent lack of transport information in developing countries.

This paper presents Open Data Kit (ODK), an extensible, open-source suite of tools designed to build information services for developing regions. ODK currently provides four tools to this end: Collect, Aggregate, Voice, and Build. Collect is a mobile platform that renders application logic and supports the manipulation of data. Aggregate provides a "click-to-deploy" server that supports data storage and transfer in the "cloud" or on local servers. Voice renders application logic using phone prompts that users respond to with keypad presses. Finally, Build is a application designer that generates the logic used by the tools. Designed to be used together or independently, ODK core tools build on existing open standards and are supported by an open-source community that has contributed additional tools. We describe four deployments that demonstrate how the decisions made in the system architecture of ODK enable services that can both push and pull information in developing regions.

Applying information and communication technologies to development (ICTD) is emerging as an interesting and motivating research area in computer science and engineering. It spans application areas from healthcare to transportation, and requires the use of computing skills from networking to user interface design. Addressing problems of developing regions and under-served communities lets students explore a different part of the ICT design space, leading to new implementation and research questions. ICTD is also an area that has the potential to excite students about the CSE field more generally, with its emphasis on enabling social benefits with technology, and is rich in possibilities for interesting student projects. In this paper we report on two offerings of a course at the University of Washington that introduce students to the field by way of 1) reading papers from literature in the area to gain exposure to this very different design mindset and 2) doing practical projects that engage students in engineering problems under unique design constraints. Our hope is that CSE educators may find our experiences useful in identifying an approach to integrating the field of ICTD into their curricula.

Individuals with cognitive impairments would prefer to live independently, however issues in wayfinding prevent many from fully living, working, and participating in their community. Our research has focused on designing, prototyping, and evaluating a mobile wayfinding system to aid such individuals. Building on the feedback gathered from potential users, we have implemented the system’s automated direction selection functionality. Using a decision-theoretic approach, we believe we can create better wayfinding experience that assists users to reach their destination more intuitively than traditional navigation systems. This paper describes the system and results from a study using systemgenerated directions that inform us of key customization factors that would provide improved wayfinding assistance for individual users.

In 2007, approximately 30% of US adults were obese, with related health care costs exceeding 100 billion dollars. Clearly, the obesity epidemic represents a growing societal concern. One challenge in weight control is the difficulty of tracking food calories consumed and calories expended by activity. This paper presents a system for automatic monitoring of calories expended using a single body-worn accelerometer. Our system uses activity inference combined with signal analysis to estimate calories expended in real-time using regression formulas developed by the American College of Sports Medicine. To validate our system, we have collected data from 51 subjects in a laboratory setting using a treadmill and a more natural field test. Actual caloric expenditure was determined using the medical "gold standard" measurement, of oxygen consumption. We are able to achieve 89% accuracy with lab data and 79% with field data -- both high enough to be useful in practice.

This work consists of two main components: (a) a longitudinal ethnographic study in Kyrgyzstan that demonstrates the importance of transportation resources in the developing world and how to plan for an appropriate ICT solution, and (b) the results of a proof-of-concept system engineered to create a bottom-up, transportation information infrastructure using only GPS and SMS. Transportation is a very important shared resource; enabling efficient and effective use of such resources aids overall development goals.

Organizations in low income regions need tools for collecting and reporting on data. Existing paper-based approaches are often slow and incomplete when compared to data collection tools on mobile devices. In this demonstration, we present the authors Android-based system in addition to broader work by the OpenRosa Consortium - a community dedicated to building open source, standards-based tools for mobile data collection, aggregation, analysis, and reporting.

Radio Frequency IDentification (RFID) deployments are becoming increasingly popular in both industrial and consumer-oriented settings. To effectively exploit and operate such deployments, important challenges must be addressed, from managing RFID data streams to handling limitations in reader accuracy and coverage. Furthermore, deployments that support pervasive computing raise additional issues related to user acceptance and system utility. To better understand these challenges, we conducted a four-week study of a building-scale EPC Class-1 Generation-2 RFID deployment, the "RFID Ecosystem", with 47 readers (160 antennas) installed throughout an 8,000 square meter building. During the study, 67 participants having over 300 tags accessed the collected RFID data through applications including an object finder and a friend tracker and several tools for managing personal data. We found that our RFID deployment produces a very manageable amount of data overall, but with orders of magnitude difference among various participants and objects. We also find that the tag detection rates tend to be low with high variance across the type of tag, participant and object. Users need expert guidance to effectively mount their tags and are encouraged by compelling applications to wear tags more frequently. Finally, probabilistic modeling and inference techniques promise to enable more complex applications by smoothing over gaps and errors in the data, but must be applied with care as they add significant computational and storage overhead.

Every year almost 10 million children die before reaching the age of five despite the fact that two-thirds of these deaths could be prevented by effective low-cost interventions. To combat this, the World Health Organization (WHO) and UNICEF developed the Integrated Management of Childhood Illness (IMCI) treatment algorithms.

Cascadia is a system that provides RFID-based pervasive computing applications with an infrastructure for specifying, extracting and managing meaningful high-level events from raw RFID data. Cascadia provides three important services. First, it allows application developers and even users to specify events using either a declarative query language or an intuitive visual language based on direct manipulation. Second, it provides an API that facilitates the development of applications which rely on RFID-based events. Third, it automatically detects the specified events, forwards them to registered applications and stores them for later use (e.g., for historical queries).

Mobile phones are an attractive platform for landmark-based pedestrian navigation systems. To be practical, such a system must be able to automatically generate lightweight directions that can be displayed on these mobile devices. We present a system that leverages an online collection of geotagged photographs to automatically generate navigational instructions. These are presented to the user as a sequence of images of landmarks augmented with directional instructions. Both the landmark selection and image augmentation are done automatically. We present a user study that indicates these generated directions are beneficial to users and suggest areas for future improvement.

In this paper we present preliminary results and future directions of work for a project in which we are building an RFID based system to sense and monitor free weight exercises.

Embedded systems are increasingly becoming connected through wireless networking. These devices now form the basis of many of today's consumer products including cell phones and video game controllers. In the "Software for Embedded Systems" class in the Department of Computer Science & Engineering at the University of Washington, we used the design of a multi-player video game as motivation for the principal concepts in wireless embedded systems. Each student in the class designed an accelerometer-based game controller and then, the class as a whole, developed a multi-player video game that allowed 28 players (the number of students in the course) to play simultaneously. In this paper, we first describe the context of the course and its goals followed by the hardware/software platform we used to realize the game controller. We then detail the pedagogical approach we used to collectively design the video game (loosely based on soccer) and conclude with the lessons learned from this group design experience and how we would enhance the project and course in the future.

The Cascadia system provides RFID-based pervasive computing applications with an infrastructure for specifying, extracting and managing meaningful high-level events from raw RFID data. Cascadia allows users to specify events of interest using a graphical interface with an intuitive visual language. Cascadia also effectively extracts these events from data in spite of the unreliability of RFID technology and the inherent ambiguity in event extraction. We demonstrate Cascadia’s technique through a digital diary application in the form of a calendar. Cascadia automatically populates the calendar with meaningful events for the user. We use data collected in a building-wide RFID deployment.

Assistive technology for wayfinding will significantly improve the quality of life for many individuals with cognitive impairments. The user interface of such a system is as crucial as the underlying implementation and localization technology. We built a system using the Wizard-of-Oz technique that let us experiment with many guidance strategies and interface modalities. Through user studies, we evaluated various configurations of the user interface for accuracy of route completion, time to completion, and user preferences. We used a counter-balanced design that included different modalities (images, audio, and text) and different routes. We found that although users were able to use all types of modalities to find their way indoors, they varied significantly in their preferred modalities. We also found that timing of directions requires careful attention, as does providing users with confirmation messages at appropriate times. Our findings suggest that the ability to adapt indoor wayfinding devices for specific users' preferences and needs will be particularly important.

Ubiquitous computing applications often use a user's context to automatically adjust their behavior to the situation. We have developed three types of wireless sensor nodes that can be worn, carried, or embedded in the environment that can provide interesting contextual information: a rich multi-sensor node to infer human activity that can be worn by a person or be part of a sensing environment, a portable wireless node for reading and writing short-range radio-frequency identification (RFID) tags, and a small wrist-watch-sized wireless display device that can serve as an easily accessible and 'glanceable' user interface. We report on our experiences in building these platforms and using them in some initial applications. We conclude with suggestions for future work in creating platforms that help blend sensor networks into ubiquitous computing.

In this paper, we propose a system that uses the wireless networking and microphone interfaces of mobile devices to determine location to room-level accuracy. The wireless network provides a synchronizing pulse along with information about the room. This is accompanied by an ultrasound beacon that allows us to resolve locations to the confines of a physical room (since audio is mostly bounded by walls). We generate the wireless data and ultrasound pulses from the existing PCs in each room; a PDA carried by a user listens for both signals. Thus, our approach does not require special hardware. We do not use ultrasound to send data. As a result we dramatically reduce the computational burden on the mobile device while also decreasing the latency of location resolution. Our results indicate that (i) ultrasound detection is robust even in noisy environments with many reflective surfaces; and (ii) that we can determine the correct room within a couple of seconds with high probability even when the ultrasound emitting PCs are not synchronized.

Pervasive computing provides an attractive vision for the future of computing. Computational power will be available everywhere. Mobile and stationary devices will dynamically connect and coordinate to seamlessly help people in accomplishing their tasks. For this vision to become a reality, developers must build applications that constantly adapt to a highly dynamic computing environment. To make the developers' task feasible, we present a system architecture for pervasive computing, called one.world. Our architecture provides an integrated and comprehensive framework for building pervasive applications. It includes services, such as discovery and migration, that help to build applications and directly simplify the task of coping with constant change. We describe our architecture and its programming model and reflect on our own and others' experiences with using it.

TiltType is a novel text entry technique for mobile devices. To enter a character, the user tilts the device and presses one or more buttons. The character chosen depends on the button pressed, the direction of tilt, and the angle of tilt. TiltType consumes minimal power and requires little board space, making it appropriate for wristwatch-sized devices. But because controlled tilting of one's forearm is fatiguing, a wristwatch using this technique must be easily removable from its wriststrap. Applications include two-way paging, text entry for watch computers, web browsing, numeric entry for calculator watches, and existing applications for PDAs.

Pervasive computing, with its focus on users and their tasks rather than on computing devices and technology, provides an attractive vision for the future of computing. But, while hardware and networking infrastructure to realize this vision are becoming a reality, precious few applications run in this infrastructure. We believe that this lack of applications stems largely from the fact that it is currently too hard to design, build, and deploy applications in the pervasive computing space. In this paper, we argue that existing approaches to distributed computing are flawed along three axes when applied to pervasive computing; we sketch out alternatives that are better suited for this space. First, application data and functionality need to be kept separate, so that they can evolve gracefully, in a global computing infrastructure. Second, applications need to be able to acquire any resource they need at any time, so that they can continuously provide their services in a highly dynamic environment. Third, pervasive computing requires a common system platform, allowing applications to be run across the range of devices and to be automatically distributed and installed.

Intrabody communication (IBC) is a wireless communications technology that uses a person's body as the transmission medium for imperceptible electrical signals. Because communication is limited to the vicinity of a person's body, ambiguities arising from communication between personal devices and environmental devices when multiple people are present can, in theory, be solved simply. Intrabody communication also potentially allows data to be transferred when a person touches an IBC-enabled device. We have designed and constructed an intrabody communication system, modeled after Zimmerman's original design, and extended it to operate up to 38.4Kbps and to calculate signal strength. In this paper, we present quantitative measurements of data error rates and signal strength while varying hand distance to transceiver plate, electrode location on the body, touch plate size and shape, and several other factors. We find that plate size and shape have only minor effects, but that the distance to plate and the coupling mechanism significantly effect signal strength. We also find that portable devices, with poor ground coupling, suffer more significant signal attenuation. Our goal is to promote design guidelines for this technology and identify the best contexts for its effective deployment.

A main advantage of control composition with modal processes [4] is the enhanced retargetability of the composed behavior over a wide variety of target architectures. Unlike previous component models that hardwire the coordination behavior either explicitly in the components or implicitly in the underlying model of computation, modal processes decouple component functionality and coordination protocols. Retargetability is achieved through the synthesis of distributed mode managers, which abstract away low-level synchronization and control communication details that would otherwise be exposed to the component designer. This paper presents an algorithm for the synthesis and optimization of distributed coordination controllers by computing an optimal projection of the global state space onto each processor. It not only minimizes interprocessor communication traffic for coordination but also reduces controller complexity by minimizing replication.

Article ipChinook: an integrated IP-based design framework for distributed embedded systems Share on Authors: Pai Chou Consystant Design Technologies, Inc., Seattle, WA Consystant Design Technologies, Inc., Seattle, WAView Profile , Ross Ortega Department of Computer Science and Engineering, Box 352350, University of Washington, Seattle, WA Department of Computer Science and Engineering, Box 352350, University of Washington, Seattle, WAView Profile , Ken Hines Department of Computer Science and Engineering, Box 352350, University of Washington, Seattle, WA Department of Computer Science and Engineering, Box 352350, University of Washington, Seattle, WAView Profile , Kurt Patridge Department of Computer Science and Engineering, Box 352350, University of Washington, Seattle, WA Department of Computer Science and Engineering, Box 352350, University of Washington, Seattle, WAView Profile , Gaetano Borriello Department of Computer Science and Engineering, Box 352350, University of Washington, Seattle, WA Department of Computer Science and Engineering, Box 352350, University of Washington, Seattle, WAView Profile Authors Info & Claims DAC '99: Proceedings of the 36th annual ACM/IEEE Design Automation ConferenceJune 1999 Pages 44–49https://doi.org/10.1145/309847.309865Online:01 June 1999Publication History 25citation519DownloadsMetricsTotal Citations25Total Downloads519Last 12 Months0Last 6 weeks0 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteGet Access

Article Next century challenges: data-centric networking for invisible computing: the Portolano project at the University of Washington Share on Authors: Mike Esler Department of Computer Science and Engineering, University of Washington, Seattle Department of Computer Science and Engineering, University of Washington, SeattleView Profile , Jeffrey Hightower Department of Computer Science and Engineering, University of Washington, Seattle Department of Computer Science and Engineering, University of Washington, SeattleView Profile , Tom Anderson Department of Computer Science and Engineering, University of Washington, Seattle Department of Computer Science and Engineering, University of Washington, SeattleView Profile , Gaetano Borriello Department of Computer Science and Engineering, University of Washington, Seattle Department of Computer Science and Engineering, University of Washington, SeattleView Profile Authors Info & Claims MobiCom '99: Proceedings of the 5th annual ACM/IEEE international conference on Mobile computing and networkingAugust 1999 Pages 256–262https://doi.org/10.1145/313451.313553Online:01 August 1999Publication History 85citation1,248DownloadsMetricsTotal Citations85Total Downloads1,248Last 12 Months16Last 6 weeks3 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteGet Access

Solutions to timing relationship analysis problems are often reported using symbolic variables and inequalities which specify linear relationships between the variables. Complex relationships can be expressed using Presburger formulas which allow Boolean relations to be specified between the inequalities. This paper develops and applies a highly effective simplification approach for Presburger formulas based on logic minimization techniques.

To explore different points in the design space of an embeddedsystem, it is important to be able to compose a designfrom reusable design components, and then map the resultingsystem description onto several possible target architectureswith different partitionings of functionality. Today's specificationmodels support composition styles that work well fordata communication but not for control communication betweenconcurrent processes to be mapped onto a distributedarchitecture. We propose a new retargetable system specificationmodel that combines the best properties of process-basedand hierarchical-FSM-based methods for modular compositionof data and control. The model lends itself to automatedsynthesis of the run-time system for coordinating tasks ondifferent processors in the system. The model and synthesismethod are illustrated with several examples of embeddedsystems.

The di#culty of embedded system co-design is increasing rapidly due to the increasing complexity of individual parts, the variety of parts available and pressure to use multiple processors to meet performance criteria. Validation toolsshouldcontain several features in order to keep up with this trend, including the ability to dynamically change detail levels, built in protection for intellectual property, and support for gradual migration of functionality from a simulation environment to the real hardware. In this paper, we present our approach to the problem which includes a geographically distributedco-simulation framework. This framework is a system of nodessuchthateach can include either portions of the simulator or real hardware. In support of this, the framework includes a mechanism for maintaining consistent versions of virtual time. 1 Introduction Embedded system co-design is becoming increasingly di#- cult due to a number of factors: # Performance criteria are harder to me...

Interface synthesis seeks to automate the process of interconnecting component.There are many levels of interconnection that must be considered including electrical, power, logic, register-transfer, device drivers, and higher software levels.This presentation ~cover a vertical stice of the interfacing problem from digital logic up to coordinating communications between software components.The focus Ml be within an embedded systems context where the interfacing is between procwsors and memory and peripheral blocks as is the case in system-on-a-chip design.The structure of the tutorial ~parallel the history of CAD efforts in this area.We wi~ begin with the early work in interface specMcation and logic synthesis then proceed on to the problems of interconnecting hardware to processors and their software, and ftish with purely software interfaces involving inter-process communication and protocols between multiple procwsors.At each level we ti discuss specflcation, synthesis, and verification aspecti as we~as higtight the currently avdable tools and on-going r=earch efforts.

In traditional distributed embedded system designs, control information is often replicated across severrd processes and kept coherent by application-specific mechanisms.Consequently, processes cannot be reused in a new system without tailoring the code to ded with the new system's control information.The modal process framework [5] provides a high-level way to specify the coherence of replicated control information independently of the behavior of the processes.Thus multiple processes can be composed without internal tailoring and without suffering from errors common in lower-level specification styles.This paper first describes a kernel-language representation for the high-level composition operators; it also presents a synthesis algorithm for the mode manager, the runtime code that maintains control information coherence within and between distributed processors.

Designers of distributed embedded systems face many challenges in determining the tradeoffs when defining a system architecture or retargeting an existing design. Communication synthesis, the automatic generation of the necessary software and hardware for system components to exchange data, is required to more effectively explore the design space and automate very error-prone tasks. This paper examines the problem of mapping a high-level specification to an arbitrary architecture that uses specific, common bus protocols for inter-processor communication. The communication model presented allows for easy retargeting to different bus topologies, protocols, and illustrates that global considerations are required to achieve a correct implementation. An algorithm is presented that partitions multihop communication timing constraints to effectively utilize the bus bandwidth along a message path. The communication synthesis tool is integrated with a system co-simulator to provide performance data for a given mapping.

There is currently great interest in using fixed arrays of FPGAs for logic emulators, custom computing devices, and software accelerators. An important part of designing such a system is determining the proper routing topology to use to interconnect the FPGAs. This topology can have a great effect on the area and delay of the resulting system. Crossbar, Hierarchical Crossbar, and Mesh interconnection schemes have all been proposed for use in FPGA-based systems. In this paper, we examine Mesh interconnection schemes, and propose several constructs for more efficient topologies. These reduce interchip delays by more than 60% over the basic four-way Mesh.

We present a novel set of tools for performing symbolic timing verificationof timing diagrams. The tools are multi-purpose with usesin verification, derivation of synthesis constraints, and design evaluation.Our methodology is based on using techniques for manipulatingPresburger formulas. We demonstrate using several interestingexamples that the method is efficient in practice and should beconsidered for inclusion in commercial tools.

Many co-simulation techniques either suffer from poor performancewhen simulating communications intensive systems, or theyrepresent communications with a uniformly low level of detail.This paper presents a technique which allows communication tobe represented at multiple levels of detail and which gives a designerthe ability to dynamically choose the appropriate level fordifferent parts of the system. This paper also presents a tool whichuses this technique and experiments which show relative simulationspeedups.

Logic partitioning is an important issue in VLSI CAD, and has been an area of active research for at least the last 25 years. Numerous approaches have been developed and many different techniques have been combined for a wide range of applications. In this paper, we examine many of the existing techniques for logic bipartitioning and present a methodology for determining the best mix of approaches The result is a novel bipartitioning algorithm that includes both new and preexisting techniques. Our algorithm produces results that are at least 16% better than the state of the art while also being efficient in run time.

Multi-FPGA systems have tremendous potential, providing a high-performance computing substrate for many different applications. One of the keys to achieving this potential is a complete, automatic mapping solution that creates high-quality mappings in the shortest possible time. In this paper, we consider one step in this process, the assignment of inter-FPGA signals to specific I/O pins on the FPGAs in a multi-FPGA system. We show that this problem can neither be handled by pin assignment methods developed for other applications nor standard routing algorithms. Although current mapping systems ignore this issue, we show that an intelligent pin assignment method can achieve both quality and mapping speed improvements over random approaches. Intelligent pin assignment methods already exist for multi-FPGA systems, but are restricted to topologies where logic-bearing FPGAs cannot be directly connected. In this paper, we provide three new algorithms for the pin assignment of multi-FPGA systems with arbitrary topologies. We compare these approaches on several mappings to current multi-FPGA systems, and show that the force-directed approach produces better mappings, in significantly shorter time, than any of the other approaches.

A central problem in embedded system co-synthesis is the generation of software for lowlevel I/O.Scheduling still remains a manual task because existing coarse-grained real-time scheduling algorithms are not applicable: they assume xed delays even though the run times are often variable, and they incur too much o v erhead.To solve this problem, we present a new static ordering technique, called interval scheduling, for meeting general timing constraints on ne-grained, variable-delay operations without using a run-time executive.

One of the critical issues for multi-FPGA systems is developing software tools for automatically mapping circuits. In this paper we consider one step in this process, partitioning. We described the task of finding partition orderings, i.e., determining the way in which a circuit should be bipartitioned so as to best map it to a multi-FPGA system. This allows multi-FPGA partitioners to harness standard partitioning techniques. We develop an algorithm for finding partition orderings, which includes a method for increasing parallelism in the process, as well as for including multi-sectioning and multi-way partitioning algorithms. This method is very efficient, and capable of handling most of the current multi-FPGA topologies.

A key aspect of the synthesis of embedded systems is the automatic integration of system components. This entails the derivation of both the hardware and software interfaces that will bind these elements together and permit them to communicate correctly and efficiently. Without the automatic synthesis of these interfaces, designers are not able to fully simulate and evaluate their systems. Frequently, they are discouraged from exploring the design space of different hardware/software partitions because practical concerns mandate minimizing changes late in the design cycle, thus leading to more costly implementations than necessary. This paper presents a set of techniques that form the basis of a comprehensive solution to the synthesis of hardware/software interfaces. Software drivers and glue logic are generated to connect processors to peripheral devices, hardware co-processors, or communication interfaces while meeting bandwidth and performance requirements. We use as examples a set of devices that communicate over an infrared local communications network (highlighting a video wrist-watch display) to explain our techniques and the need for design space exploration tools for embedded systems.

Determining the time separation of events is a fundamental problem in the analysis, synthesis, and optimization of concurrent systems. Applications range from logic optimization of asynchronous digital circuits to evaluation of execution times of programs for real-time systems. We present an efficient algorithm to find exact (tight) bounds on the separation time of events in an arbitrary process graph without conditional behavior. This result is more general than the methods presented in several previously published papers as it handles cyclic graphs and yields the tightest possible bounds on event separations. The algorithm is based on a functional decomposition technique that permits the implicit evaluation of an infinitely unfolded process graph. Examples are presented that demonstrate the utility and efficiency of the solution. The algorithm will form a basis for exploration of timing-constrained synthesis techniques.>

Field-programmable gate arrays (FPGAs) are an important implementation medium for digital logic. Unfortunately, they currently suffer from poor silicon area utilization due to routing constraints. In this paper we present Triptych, an FPGA architecture designed to achieve improved logic density with competitive performance. This is done by allowing a per-mapping tradeoff between logic and routing resources, and with a routing scheme designed to match the structure of typical circuits. We show that, using manual placement, this architecture yields a logic density improvement of up to a factor of 3.5 over commercial FPGAs, with comparable performance. We also describe Montage, the first FPGA architecture to fully support asynchronous and synchronous interface circuits.

Abstract { Existing software scheduling techniques limit the functions that can be implemented in software to those with a restricted class of timing constraints, in particular those with a coarse-grained, uniform, periodic behavior. In practice, however, many systems change their I/O behavior in response to the inputs from the environment. This paper considers one such class of systems, called reactive real-time systems, where timing requirements can include sequencing, rate, and response time constraints. We present a static, non-preemptive, ne-grained software scheduling algorithm to meet these constraints. This algorithm is suitable for control-dominated embedded systems with hard real-time constraints, and is part of the core of a hardware/software co-synthesis system. I

A fundamental timing analysis problem in the veri cation and synthesis of interface logic circuitry is the determination of allowable time separations, or skews between interface events, given timing constraints and circuit propagation delays.These skews are used to verify timing properties and determine allowable propagation delays for logic synthesis.This paper presents an algorithm that provides tighter skew bounds with better asymptotic running time than previous methods, and sho ws how to apply the method to synthesis tasks.

There is currently great interest in using fixed arrays of FPGAs for logic emulators, custom computing devices, and software accelerators. An important part of designing such a system is determining the proper routing topology to use to interconnect the FPGAs. This topology can have a great effect on the area and delay of the resulting system. Tree, bipartite graph, and mesh inter-connection schemes have all been proposed for use in FPGA-based systems. In this paper we examine mesh interconnection schemes, and propose several constructs for more efficient topologies. These reduce inter-chip delays by more than 60% over the basic 4-way Mesh.>

Determining the time separation of events is a fundamental problem in the analysis, synthesis, and optimization of concurrent systems. We present results of applying an efficient algorithm to solve this problem of three different application domains. These are: analysis of instruction execution times of an asynchronous multiprocessor, analysis of a high-performance mixed asynchronous/synchronous communication interface, and isochronic fork analysis in asynchronous circuit synthesis. The algorithm we use yields exact (tight) bounds on the separation time of events in an arbitrary process graph without conditional behavior. This class of graphs is quite large and includes graphs that are not strongly connected. The algorithm is based on a functional decomposition technique that permits the implicit evaluation of an infinitely unfolded process graph.

Determining the time separation of events is a fundamental problem in the analysis, synthesis, and optimization of concurrent systems. Applications range from logic optimization of asynchronous digital circuits to evaluation of execution times of programs for real-time systems. We present an efficient algorithm to find exact (tight) bounds on the separation time of events in an arbitrary process graph without conditional behavior. The algorithm is based on a functional decomposition technique that permits the implicit evaluation of an infinitely unfolded process graph.>

A tool that automates the synthesis of the hardware/software interface between a microcontroller and the devices it controls is described. Optimizations of the synthesis process focus primarily on the minimization of interface hardware and also the code size of the device driver routines. This interface synthesis problem is specified and the data structures used to represent the microcontroller, devices, and hardware and software primitives are described. The port allocation algorithm is presented and the features of this interface synthesis tool are highlighted with two practical examples.>

Article Free Access Share on OEsim: a simulator for timing behavior Authors: Tod Amon Department of Computer Science and Engineering, University of Washington, Seattle, WA Department of Computer Science and Engineering, University of Washington, Seattle, WAView Profile , Gaetano Borriello Department of Computer Science and Engineering, University of Washington, Seattle, WA Department of Computer Science and Engineering, University of Washington, Seattle, WAView Profile Authors Info & Claims DAC '91: Proceedings of the 28th ACM/IEEE Design Automation ConferenceJune 1991 Pages 656–661https://doi.org/10.1145/127601.127746Published:01 June 1991Publication History 7citation138DownloadsMetricsTotal Citations7Total Downloads138Last 12 Months2Last 6 weeks1 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF

In synthesizing a circuit from its description in a concurrent programming language, it is necessary to make decisions about how to implement synchronization constructs such as send and receive statements.The semantic model of these constructs is an infinite length FIFO queue that can handle all send events until they are paired up with corresponding receive events.In this paper, we describe an algorithm to size these synchronization queues while permitting the maximum parallelism between the communicating processes (circuits).It is an example of higher level synthesis in that the user does not include an explicit description of the queue in the specification as is necessary in current high level synthesis systems.I.

The timing optimization of multiphase logic entails the reduction of the overall cycle time of the machine and/or input-to-output delays by distributing computation throughout the entire clock cycle. A tool has been developed to automatically perform this optimization task, and it has been implemented as a set of extensions to the combinational logic optimization tool, misII. The algorithms yield improvements that are on average 10-20% better than what is achievable using purely combinational logic optimization tools that do not move logic across latches. These improvements represent 75% of what would be possible in the most idealized case. Results on simple two-phase circuits show average input-to-output delay improvements of 13% with area penalties of 11%. For a four-phase controller used in the SPUR processor it yields an improvement in cycle time of 18% with an area penalty of 11%. Experiments indicate that the optimization algorithm is highly insensitive to parameter variations in the underlying combinational logic optimization routines and initial state assignment.>

Combining event and data-flow graphs into a single unified representation is addressed. A unified behavior graph is presented, and the algorithms required to support automatic synthesis are obtained. The new descriptive conventions are shown to be concise and to possess straightforward mappings to hardware. The algorithms are demonstrated to be of practical complexity (O(n/sup 2/), where N is the number of interface events). A practical example demonstrates how the representation is used, and synthesis results from five examples show that the synthesized circuitry is comparable to that achieved with other automatic methods or by experienced human designers.>

This paper compares the performance of executing compiled Prolog code on two different architectures under development at U. C. Berkeley. The first is the PLM, a special-purpose CISC architecture intended as a coprocessor for a host machine. The second is SPUR, a general-purpose RISC architecture that supports tagged data. Fourteen standard benchmark programs were run on both the PLM and SPUR simulators. The compiled code for SPUR was obtained by simple macro-expansion of PLM code generated by the PLM Prolog compiler. The two implementations are compared with regard to static and dynamic program size, execution speed, and memory system performance. On average, the macrocoded SPUR implementation has a static code size 14 times larger than the PLM, executes 16 times more instructions, yet requires only 2.3 times the number of machine cycles (or has the performance of 0.43 PLMs). When memory system performance is taken into account, SPUR is equivalent to 0.29 PLMs. Optimizations of the macro-expanded code and minor architectural changes to SPUR would increase this ratio to 0.53, or 0.60 for the largest benchmarks. Thus a tagged RISC architecture can execute Prolog at least half as fast as a special-purpose CISC architecture for Prolog.