Networking Wireless Sensors
Networking Wireless Sensors Wireless sensor networks promise an unprecedented fine-grained interface between the virtual and physical worlds. They are one of the most rapidly devel- oping new information technologies, with applications in a wide range of fields including industrial process control, security and surveillance, environmental sensing, and structural health monitoring. This book is motivated by the urgent need to provide a comprehensive and organized survey of the field. It shows how the core challenges of energy efficiency, robustness, and autonomy are addressed in these systems by networking techniques across multiple layers. The topics covered include network deployment, localization, time synchronization, wire- less radio characteristics, medium-access, topology control, routing, data-centric techniques, and transport protocols. Ideal for researchers and designers seeking to create new algorithms and protocols and engineers implementing integrated solutions, it also contains many exercises and can be used by graduate students taking courses in networks. B HASKAR K RISHNAMACHARI is an assistant professor in the Department of Electrical Engineering Systems at the University of Southern California. ii ii Networking Wireless Sensors Bhaskar Krishnamachari Sleep-oriented MAC – Efficient routing Data-centric concepts – Congestion control Deployment & configuration – Localization Synchronization – Wireless characteristics camʙʀɪdɢe uɴɪveʀsɪtʏ pʀess Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo Cambridge University Press The Edinburgh Building, Cambridge cʙ2 2ʀu, UK First published in print format ɪsʙɴ-13 978-0-521-83847-4 ɪsʙɴ-13 978-0-511-14055-6 © Cambridge University Press 2005 2005 Information on this title: www.cambridge.org/9780521838474 This publication is in copyright. Subject to statutory exception and to the provision of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. ɪsʙɴ-10 0-511-14055-x ɪsʙɴ-10 0-521-83847-9 Cambridge University Press has no responsibility for the persistence or accuracy of uʀʟs for external or third-party internet websites referred to in this publication, and does not guarantee that any content on such websites is, or will remain, accurate or appropriate. Published in the United States of America by Cambridge University Press, New York www.cambridge.org hardback eBook (NetLibrary) eBook (NetLibrary) hardback To Shriram & Zhen, Amma & Appa ii ii Contents Preface page xi 1 Introduction 1 1.1 Wireless sensor networks: the vision 1 1.2 Networked wireless sensor devices 2 1.3 Applications of wireless sensor networks 4 1.4 Key design challenges 6 1.5 Organization 9 2 Network deployment 10 2.1 Overview 10 2.2 Structured versus randomized deployment 11 2.3 Network topology 12 2.4 Connectivity in geometric random graphs 14 2.5 Connectivity using power control 18 2.6 Coverage metrics 22 2.7 Mobile deployment 26 2.8 Summary 27 Exercises 28 3 Localization 31 3.1 Overview 31 3.2 Key issues 32 3.3 Localization approaches 34 3.4 Coarse-grained node localization using minimal information 34 vii viii Contents 3.5 Fine-grained node localization using detailed information 39 3.6 Network-wide localization 43 3.7 Theoretical analysis of localization techniques 51 3.8 Summary 53 Exercises 54 4 Time synchronization 57 4.1 Overview 57 4.2 Key issues 58 4.3 Traditional approaches 60 4.4 Fine-grained clock synchronization 61 4.5 Coarse-grained data synchronization 67 4.6 Summary 68 Exercises 68 5 Wireless characteristics 70 5.1 Overview 70 5.2 Wireless link quality 70 5.3 Radio energy considerations 77 5.4 The SINR capture model for interference 78 5.5 Summary 79 Exercises 80 6 Medium-access and sleep scheduling 82 6.1 Overview 82 6.2 Traditional MAC protocols 82 6.3 Energy efficiency in MAC protocols 86 6.4 Asynchronous sleep techniques 87 6.5 Sleep-scheduled techniques 91 6.6 Contention-free protocols 96 6.7 Summary 100 Exercises 101 7 Sleep-based topology control 103 7.1 Overview 103 7.2 Constructing topologies for connectivity 105 7.3 Constructing topologies for coverage 109 7.4 Set K-cover algorithms 113 Contents ix 7.5 Cross-layer issues 114 7.6 Summary 116 Exercises 116 8 Energy-efficient and robust routing 119 8.1 Overview 119 8.2 Metric-based approaches 119 8.3 Routing with diversity 122 8.4 Multi-path routing 125 8.5 Lifetime-maximizing energy-aware routing techniques 128 8.6 Geographic routing 130 8.7 Routing to mobile sinks 133 8.8 Summary 136 Exercises 137 9 Data-centric networking 139 9.1 Overview 139 9.2 Data-centric routing 140 9.3 Data-gathering with compression 143 9.4 Querying 147 9.5 Data-centric storage and retrieval 156 9.6 The database perspective on sensor networks 159 9.7 Summary 162 Exercises 163 10 Transport reliability and congestion control 165 10.1 Overview 165 10.2 Basic mechanisms and tunable parameters 167 10.3 Reliability guarantees 168 10.4 Congestion control 170 10.5 Real-time scheduling 175 10.6 Summary 177 Exercises 178 11 Conclusions 179 11.1 Summary 179 11.2 Further topics 180 References 183 Index 197 [...]... wake-up modes 4 Sensors: Due to bandwidth and power constraints, WSN devices primarily support only low-data-rate sensing Many applications call for multi-modal sensing, so each device may have several sensors on board The specific 4 Introduction sensors used are highly dependent on the application; for example, they may include temperature sensors, light sensors, humidity sensors, pressure sensors, accelerometers,... embedded wireless sensor networks for dense sensing applications 1 2 Introduction Figure 1.1 A Berkeley mote (MICAz MPR2400 series) Perhaps one of the earliest research efforts in this direction was the lowpower wireless integrated microsensors (LWIM) project at UCLA funded by DARPA [98] The LWIM project focused on developing devices with low-power electronics in order to enable large, dense wireless. .. succeeded by the Wireless Integrated Networked Sensors (WINS) project a few years later, in which researchers at UCLA collaborated with Rockwell Science Center to develop some of the first wireless sensor devices Other early projects in this area, starting around 1999–2000, were also primarily in academia, at several places including MIT, Berkeley, and USC Researchers at Berkeley developed embedded wireless. .. role in the ongoing wireless sensor networks revolution 1.2 Networked wireless sensor devices As shown in Figure 1.2, there are several key components that make up a typical wireless sensor network (WSN) device: 1 Low-power embedded processor: The computational tasks on a WSN device include the processing of both locally sensed information as well as information communicated by other sensors At present,... spatio-temporal resolution As a result, wireless sensor networks also have the potential to engender new breakthrough scientific advances While the notion of networking distributed sensors and their use in military and industrial applications dates back at least to the 1970s, the early systems were primarily wired and small in scale It was only in the 1990s – when wireless technologies and low-power VLSI... patience and help Bhaskar Krishnamachari 1 Introduction 1.1 Wireless sensor networks: the vision Recent technological advances allow us to envision a future where large numbers of low-power, inexpensive sensor devices are densely embedded in the physical environment, operating together in a wireless network The envisioned applications of these wireless sensor networks range widely: ecological habitat... processing of both locally sensed information as well as information communicated by other sensors At present, primarily due to economic Networked wireless sensor devices 3 Sensors Memory Processor GPS Radio transceiver Power source Figure 1.2 Schematic of a basic wireless sensor network device constraints, the embedded processors are often significantly constrained in terms of computational power (e.g.,... design concepts developed for wireless sensor networks in recent years The topics covered are wide-ranging: deployment, localization, synchronization, wireless link characteristics, medium-access, sleep scheduling and topology control, routing, data-centric concepts, and congestion control This book has its origins in notes, lectures, and discussions from a graduate course on wireless sensor networks that... particular ingredient or changing the heat settings The key advantage of creating wireless networks of sensors in these environments is that they can significantly improve both the cost and the flexibility associated with installing, maintaining, and upgrading wired systems [131] As an indication of the commercial promise of wireless embedded networks, it should be noted that there are already several... necessary in many applications to provide guarantees that a network of unattended wireless sensors can remain operational without any replacements for several years Hardware improvements in battery design and energy harvesting techniques will offer only partial solutions This is the reason that most protocol designs in wireless sensor networks are designed explicitly with energy efficiency as the primary . temperature sensors, light sensors, humidity sensors, pressure sensors, accelerometers, magnetometers, chemical sensors, acoustic sensors, or even low-resolution. Networking Wireless Sensors Wireless sensor networks promise an unprecedented fine-grained