Synthesis Lectures on Mobile & Pervasive Computing

This lecture provides an introduction to the problem of managing the energy demand of mobile devices. Reducing energy consumption, primarily with the goal of extending the lifetime of battery-powered devices, has emerged as a fundamental challenge in mobile computing and wireless communication. The focus of this lecture is on a systems approach where software techniques exploit state-of-the-art architectural features rather than relying only upon advances in lower-power circuitry or the slow improvements in battery technology to solve the problem. Fortunately, there are many opportunities to innovate on managing energy demand at the higher levels of a mobile system. Increasingly, device components offer low power modes that enable software to directly affect the energy consumption of the system. The challenge is to design resource management policies to effectively use these capabilities. The lecture begins by providing the necessary foundations, including basic energy terminology andwidely accepted metrics, system models of how power is consumed by a device, and measurement methods and tools available for experimental evaluation. For components that offer low power modes, management policies are considered that address the questions of when to power down to a lower power state and when to power back up to a higher power state. These policies rely on detecting periods when the device is idle as well as techniques for modifying the access patterns of a workload to increase opportunities for power state transitions. For processors with frequency and voltage scaling capabilities, dynamic scheduling policies are developed that determine points during execution when those settings can be changed without harming quality of service constraints. The interactions and tradeoffs among the power management policies of multiple devices are discussed. We explore how the effective power management on one component of a system may have either a positive or negative impact on overall energy consumption or on the design of policies for another component. The important role that application-level involvement may play in energy management is described, with several examples of cross-layer cooperation. Application program interfaces (APIs) that provide information flow across the application-OS boundary are valuable tools in encouraging development of energy-aware applications. Finally, we summarize the key lessons of this lecture and discuss future directions in managing energy demand.

Managing data in a mobile computing environment invariably involves caching or replication. In many cases, a mobile device has access only to data that is stored locally, and much of that data arrives via replication from other devices, PCs, and services. Given portable devices with limited resources, weak or intermittent connectivity, and security vulnerabilities, data replication serves to increase availability, reduce communication costs, foster sharing, and enhance survivability of critical information. Mobile systems have employed a variety of distributed architectures from client–server caching to peer-to-peer replication. Such systems generally provide weak consistency models in which read and update operations can be performed at any replica without coordination with other devices. The design of a replication protocol then centers on issues of how to record, propagate, order, and filter updates. Some protocols utilize operation logs, whereas others replicate state. Systems might provide best-effort delivery, using gossip protocols or multicast, or guarantee eventual consistency for arbitrary communication patterns, using recently developed pairwise, knowledge-driven protocols. Additionally, systems must detect and resolve the conflicts that arise from concurrent updates using techniques ranging from version vectors to read–write dependency checks. This lecture explores the choices faced in designing a replication protocol, with particular emphasis on meeting the needs of mobile applications. It presents the inherent trade-offs and implicit assumptions in alternative designs. The discussion is grounded by including case studies of research and commercial systems including Coda, Ficus, Bayou, Sybase’s iAnywhere, and Microsoft’s Sync Framework. Table of Contents: Introduction / System Models / Data Consistency / Replicated Data Protocols / Partial Replication / Conflict Management / Case Studies / Conclusions / Bibliography

This lecture presents a first compendium of established and emerging standards in pervasive computing systems. The lecture explains the role of each of the covered standards and explains the relationship and interplay among them. Hopefully, the lecture will help piece together the various standards into a sensible and clear landscape. The lecture is a digest, reorganization, and a compilation of several short articles that have been published in the “Standards and Emerging Technologies” department of the IEEE Pervasive Computing magazine. The articles have been edited and shortened or expanded to provide the necessary focus and uniform coverage depth. There are more standards and common practices in pervasive systems than the lecture could cover. However, systems perspective and programmability of pervasive spaces, which are the main foci of the lecture, set the scope and determined which standards should be included. The lecture explains what it means to program a pervasive space andintroduces the new requirements brought about by pervasive computing. Among the standards the lecture covers are sensors and device standards, service-oriented device standards, service discovery and delivery standards, service gateway standards, and standards for universal interactions with pervasive spaces. In addition, the emerging sensor platform and domestic robots technologies are covered and their essential new roles explained. The lecture also briefly covers a set of standards that represents an ecosystem for the emerging pervasive healthcare industry. Audiences who may benefit from this lecture include (1) academic and industrial researchers working on sensor-based, pervasive, or ubiquitous computing R&D; (2) system integrator consultants and firms, especially those concerned with integrating sensors, actuators, and devices to their enterprise and business systems; (3) device, smart chips, and sensor manufacturers; (4) government agencies; (5) the healthcare IT and pervasive health industries; and (6) other industries such as logistics, manufacturing, and the emerging smart grid and environment sustainability industries. Table of Contents: Preface / Acknowledgments / Introduction / Sensor and Device Standards / Service-Oriented Device Architecture (SODA) / Sensor Platforms / Service Discovery and Delivery Standards / The Open Services Gateway Initiative (OSGi ) / Universal Interactions / Domestic Robots for Smart Space Interactions / Continua: An Interoperable Personal Health Echosystem / References / Author Biography

Fueled by falling display hardware costs and rising demand, digital signage and pervasive displays are becoming ever more ubiquitous. Such systems have traditionally been used for advertising and information dissemination, with digital signage commonplace in shopping malls, airports and public spaces. While advertising and broadcasting announcements remain important applications, developments in sensing and interaction technologies are enabling entirely new classes of display applications that tailor content to the situation and audience of the display. As a result, signage systems are beginning to transition from simple broadcast systems to rich platforms for communication and interaction.

In this lecture, we provide an introduction to this emerging field for researchers and practitioners interested in creating state-of-the-art pervasive display systems. We begin by describing the history of pervasive display research, providing illustrations of key systems, from pioneering work on supporting collaboration to contemporary systems designed for personalized information delivery. We then consider what the near future might hold for display networks -- describing a series of compelling applications that are being postulated for future display networks. Creating such systems raises a wide range of challenges and requires designers to make a series of important trade-offs. We dedicate four chapters to key aspects of pervasive display design: audience engagement, display interaction, system software, and system evaluation. These chapters provide an overview of current thinking in each area. Finally, we present a series of case studies of display systems and our concluding remarks.

It is easy to imagine that a future populated with an ever-increasing number of mobile and pervasive devices that record our minute goings and doings will significantly expand the amount of information that will be collected, stored, processed, and shared about us by both corporations and governments. The vast majority of this data is likely to benefit us greatly—making our lives more convenient, efficient, and safer through custom-tailored and context-aware services that anticipate what we need, where we need it, and when we need it. But beneath all this convenience, efficiency, and safety lurks the risk of losing control and awareness of what is known about us in the many different contexts of our lives. Eventually, we may find ourselves in a situation where something we said or did will be misinterpreted and held against us, even if the activities were perfectly innocuous at the time. Even more concerning, privacy implications rarely manifest as an explicit, tangible harm. Instead, most privacy harms manifest as an absence of opportunity, which may go unnoticed even though it may substantially impact our lives.
In this Synthesis Lecture, we dissect and discuss the privacy implications of mobile and pervasive computing technology. For this purpose, we not only look at how mobile and pervasive computing technology affects our expectations of—and ability to enjoy—privacy, but also look at what constitutes ""privacy"" in the first place, and why we should care about maintaining it. We describe key characteristics of mobile and pervasive computing technology and how those characteristics lead to privacy implications. We discuss seven approaches that can help support end-user privacy in the design of mobile and pervasive computing technologies, and set forward six challenges that will need to be addressed by future research.
The prime target audience of this lecture are researchers and practitioners working in mobile and pervasive computing who want to better understand and account for the nuanced privacy implications of the technologies they are creating. Those new to either mobile and pervasive computing or privacy may also benefit from reading this book to gain an overview and deeper understanding of this highly interdisciplinary and dynamic field.

This lecture provides an introduction to Radio Frequency Identification (RFID), a technology enabling automatic identification of objects at a distance without requiring line-of-sight. Electronic tagging can be divided into technologies that have a power source (active tags), and those that are powered by the tag interrogation signal (passive tags); the focus here is on passive tags. An overview of the principles of the technology divides passive tags into devices that use either near field or far field coupling to communicate with a tag reader. The strengths and weaknesses of the approaches are considered, along with the standards that have been put in place by ISO and EPCGlobal to promote interoperability and the ubiquitous adoption of the technology. A section of the lecture has been dedicated to the principles of reading co-located tags, as this represents a significant challenge for a technology that may one day be able to automatically identify all of the items in your shopping cart in a just few seconds. In fact, RFID applications are already quite extensive and this lecture classifies the primary uses. Some variants of modern RFID can also be integrated with sensors enabling the technology to be extended to measure parameters in the local environment, such as temperature & pressure. The uses and applications of RFID sensors are further described and classified. Later we examine important lessons surrounding the deployment of RFID for the Wal-Mart and the Metro AG store experiences, along with deployments in some more exploratory settings. Extensions of RFID that make use of read/write memory integrated with the tag are also discussed, in particular looking at novel near term opportunities. Privacy and social implications surrounding the use of RFID inspire recurring debates whenever there is discussion of large scale deployment; we examine the pros and cons of the issues and approaches for mitigating the problems. Finally, the remaining challenges of RFID are considered and we look to the future possibilities for the technology. Table of Contents: Introduction / Principles of Radio Frequency Identification / RFID Industry Standards / Reading Collected RFID Tags / Applications of RFID Tagging / RFID Incorporating Sensing / Deployment and Experience with RFID Systems / Privacy, Kill Switches, and Blocker Tags / Opportunities for RFID Integrated with Memory / Challenges, Future Technology, and Conclusion

The confluence of decades of computer science and computer engineering research in multimodal interaction (e.g., speech and gesture recognition), machine learning (e.g., classification and feature extraction), software (e.g., web browsers, distributed agents), electronics (e.g., energy-efficient microprocessors, head-mounted displays), design methodology in user-centered design, and rapid prototyping have enabled a new class of computers—wearable computers. The lecture takes the viewpoint of a potential designer or researcher in wearable computing. Designing wearable computers requires attention to many different factors because of the computer’s closeness to the body and its use while performing other tasks. For the purposes of discussion, we have created the UCAMP framework, which consists of the following factors: user, corporal, attention, manipulation, and perception. Each of these factors and their importance is described. A number of example prototypes developed by the authors,as well as by other researchers, are used to illustrate these concepts. Wearable computers have established their first foothold in several application domains, such as vehicle and aircraft maintenance and manufacturing, inspection, language translation, and other areas. The lecture continues by describing the next step in the evolution of wearable computers, namely, context awareness. Context-aware computing takes into account a user’s state and surroundings, and the mobile computer modifies its behavior based on this information. A user’s context can be quite rich, consisting of attributes such as physical location, physiological state, personal history, daily behavioral patterns, and so forth. If a human assistant were given such context, he or she would make decisions in a proactive fashion, anticipating user needs, and acting as a proactive assistant. The goal is to enable mobile computers to play an analogous role, exploiting context information to significantly reduce demands onhuman attention. Context-aware intelligent agents can deliver relevant information when a user needs that information. These data make possible many exciting new applications, such as augmented reality, context-aware collaboration, and augmented manufacturing. The combined studies and research reported in this lecture suggest a number of useful guidelines for designing wearable computing devices. Also included with the guidelines is a list of questions that designers should consider when beginning to design a wearable computer. The research directions section emphasizes remaining challenges and trends in the areas of user interface, modalities of interaction, and wearable cognitive augmentation. Finally, we summarize the most important challenges and conclude with a projection of future directions in wearable computing. Table of Contents: Introduction / The Wearable Computing UCAMP / Design Guidelines for Wearable Computing / Research Directions / Conclusions and Future Challenges

Advances in electronic location technology and the coming of age of mobile computing have opened the door for location-aware applications to permeate all aspects of everyday life. Location is at the core of a large number of high-value applications ranging from the life-and-death context of emergency response to serendipitous social meet-ups. For example, the market for GPS products and services alone is expected to grow to US$200 billion by 2015. Unfortunately, there is no single location technology that is good for every situation and exhibits high accuracy, low cost, and universal coverage. In fact, high accuracy and good coverage seldom coexist, and when they do, it comes at an extreme cost. Instead, the modern localization landscape is a kaleidoscope of location systems based on a multitude of different technologies including satellite, mobile telephony, 802.11, ultrasound, and infrared among others. This lecture introduces researchers and developers to the most popular technologies and systems for location estimation and the challenges and opportunities that accompany their use. For each technology, we discuss the history of its development, the various systems that are based on it, and their trade-offs and their effects on cost and performance. We also describe technology-independent algorithms that are commonly used to smooth streams of location estimates and improve the accuracy of object tracking. Finally, we provide an overview of the wide variety of application domains where location plays a key role, and discuss opportunities and new technologies on the horizon. Table of Contents: Introduction / The Global Positioning System / Infrared and Ultrasonic Systems / Location Esimation with 802.11 / Cellular-Based Systems / Other Approaches / Improving Localization Accuracy / Location-Based Applications and Services / Challenges and Opportunities / References

Testing applications for mobile phones is difficult, time-consuming, and hard to do effectively. Many people have limited their testing efforts to hands-on testing of an application on a few physical handsets, and they have to repeat the process every time a new version of the software is ready to test. They may miss many of the permutations of real-world use, and as a consequence their users are left with the unpleasant mess of a failing application on their phone. Test automation can help to increase the range and scope of testing, while reducing the overhead of manual testing of each version of the software. However automation is not a panacea, particularly for mobile applications, so we need to pick our test automation challenges wisely. This book is intended to help software and test engineers pick appropriately to achieve more; and as a consequence deliver better quality, working software to users. This Synthesis lecture provides practical advice based on direct experience of using software test automation to help improve the testing of a wide range of mobile phone applications, including the latest AJAX applications. The focus is on applications that rely on a wireless network connection to a remote server, however the principles may apply to other related fields and applications. We start by explaining terms and some of the key challenges involved in testing smartphone applications. Subsequent chapters describe a type of application e.g. markup, AJAX, Client, followed by a related chapter on how to test each of these applications. Common test automation techniques are covered in a separate chapter, and finally there is a brief chapter on when to test manually. The book also contains numerous pointers and links to further material to help you to improve your testing using automation appropriately. Table of Contents: Introduction / Markup Languages / Testing Techniques for Markup Applications / AJAX Mobile Applications / Testing Mobile AJAX Applications / Client Applications / Testing Techniques for Client Applications / Common Techniques / When to Test Manually / Future Work / Appendix A: Links and References / Appendix B: Data Connectivity / Appendix C: Configuring Your Machine

This lecture provides an introduction to cyber foraging, a topic that lies at the intersection of mobile and cloud computing. Cyber foraging dynamically augments the computing resources of mobile computers by opportunistically exploiting fixed computing infrastructure in the surrounding environment. In a cyber foraging system, applications functionality is dynamically partitioned between the mobile computer and infrastructure servers that store data and execute computation on behalf of mobile users. The location of application functionality changes in response to user mobility, platform characteristics, and variation in resources such as network bandwidth and CPU load. Cyber foraging also introduces a new, surrogate computing tier that lies between mobile users and cloud data centers. Surrogates are wired, infrastructure servers that offer much greater computing resources than those offered by small, battery-powered mobile devices. Surrogates are geographically distributed to be as close as possible to mobile computers so that they can provide substantially better response time to network requests than that provided by servers in cloud data centers. For instance, surrogates may be co-located with wireless hotspots in coffee shops, airport lounges, and other public locations. This lecture first describes how cyber foraging systems dynamically partition data and computation. It shows how dynamic partitioning can often yield better performance, energy efficiency, and application quality than static thin-client or thick-client approaches for dividing functionality between cloud and mobile computers. The lecture then describes the design of the surrogate computing tier. It shows how strong isolation can enable third-party computers to host computation and store data on behalf of nearby mobile devices. It then describes how surrogates can provide reasonable security and privacy guarantees to the mobile computers that use them. The lecture concludes with a discussion of data staging, in which surrogates temporarily store data in transit between cloud servers and mobile computers in order to improve transfer bandwidth and energy efficiency. Table of Contents: Introduction / Partitioning / Management / Security and Privacy / Data Staging / Challenges and Opportunities

This Synthesis Lecture presents a discussion of Quality of Service (QoS) in wireless networks over unlicensed spectrum. The topic is presented from the point of view of protocols for wireless networks (e.g., 802.11) rather than the physical layer point of view usually discussed for cellular networks in the licensed wireless spectrum. A large number of mobile multimedia wireless applications are being deployed over WiFi (IEEE 802.11) and Bluetooth wireless networks and the number will increase in the future as more phones, tablets, and laptops are equipped with these unlicensed spectrum wireless interfaces. Achieving QoS objectives in wireless networks is challenging due to limited wireless resources, wireless nodes interference, wireless shared media, node mobility, and diverse topologies. The author presents the QoS problem as (1) an optimization problem with different constraints coming from the interference, mobility, and wireless resource constraints and (2) an algorithmic problemwith fundamental algorithmic functions within wireless resource management and protocols. Table of Contents: Preface / Basics of Quality of Service in Wireless Networks / QoS-Aware Resource Allocation / Bandwidth Management / Delay Management / Routing / Acknowledgment / References / Author Biography

Mobile platform development has lately become a technological war zone with extremely dynamic and fluid movement, especially in the smart phone and tablet market space. This Synthesis lecture is a guide to the latest developments of the key mobile platforms that are shaping the mobile platform industry. The book covers the three currently dominant native platforms -- iOS, Android and Windows Phone -- along with the device-agnostic HTML5 mobile web platform. The lecture also covers location-based services (LBS) which can be considered as a platform in its own right. The lecture utilizes a sample application (TwitterSearch) that the authors show programmed on each of the platforms. Audiences who may benefit from this lecture include: (1) undergraduate and graduate students taking mobile computing classes or self-learning the mobile platform programmability road map; (2) academic and industrial researchers working on mobile computing R&D projects; (3) mobile app developers for a specific platform who may be curious about other platforms; (4) system integrator consultants and firms concerned with mobilizing businesses and enterprise apps; and (5) industries including health care, logistics, mobile workforce management, mobile commerce and payment systems and mobile search and advertisement. Table of Contents: From the Newton to the iPhone / iOS / Android / Windows Phone / Mobile Web / Platform-in-Platform: Location-Based Services (LBS) / The Future of Mobile Platforms / TwitterSearch Sample Application

This book teaches readers how wireless networks work, why some of their properties impact wireless network performance at the application level, and what both network engineers and application developers can do to cope with these challenges. Internet users increasingly rely on wireless access links for diverse tasks such as web browsing, video conferencing, interactive games, and data sharing. Irrespective of how they access the Internet, they expect good performance and a high quality of experience. Unfortunately, wireless access networks are much more challenging to build than wired networks. In wired networks, signals used for communication are contained in a carefully engineered transmission medium. In contrast, wireless signals travel in our physical environment, where the presence of obstacles, interference, and mobility can affect communication. In addition, network performance can differ significantly across physical environments. As a result, the performance of wireless links is often lower and less predictable than that of wired links. The author structured the book according to the layers in the Internet protocol stack, similar to traditional network books. However, rather than presenting a general description of each layer, the focus is on wireless networks and how they differ from wired networks.