Edgar H. Callaway, Jr.
Wireless
Sensor
Networks
Architectures
and
Protocols
A
AUERBACH PUBLICATIONS
A CRC Press CompanyContents
Chapter 1 Introduction to Wireless Sensor Networks 1
1.1 Applications and Motivation 1 1.1.1 Industrial Control and Monitoring 2 1.1.2 Home Automation and Consumer Electronics 4 1.1.3 Security and Military Sensing 6 1.1.4 Asset Tracking and Supply Chain Management 7 1.1.5 Intelligent Agriculture and Environmental Sensing 9 1.1.6 Health Monitoring 10 1.2 Network Performance Objectives 11 1.2.1 Low Power Consumption 11 1.2.2 Low Cost 12 1.2.3 Worldwide Availability 13 1.2.4 Network Type 13 1.2.5 Security 13 1.2.6 Data Throughput 15 1.2.7 Message Latency 16 1.2.8 Mobility 16 1.3 Contributions of this Book 16 1.4 Organization of this Book 17 References 17
Chapter 2 The Development of Wireless Sensor Networks 21
2.1 Early Wireless Networks 21 2.2 Wireless Data Networks 29 2.2.1 The ALOHA System 29 2.2.2 The PRNET System 30 2.2.3 Amateur Packet Radio Networks 30 2.2.4 Wireless Local Area Networks (WLANs) 31 2.2.5 Wireless Personal Area Networks (WPANs) 32 2.3 Wireless Sensor and Related Networks 33 2.3.1 WINS 33
Contents
2.3.2 PicoRadio 34 2.3.3 uAMPS 34 2.3.4 Terminodes, MANET, and Other Mobile Ad Hoc
Networks 34 2.3.5 Underwater Acoustic and Deep Space Networks 35 2.4 Conclusion 35 References 36
Chapter 3 The Physical Layer 41
3.1 Introduction 41 3.2 Some Physical Layer Examples 42 3.2.1 Bluetooth 42 3.2.2 IEEE 802.11b 42 3.2.3 Wireless Sensor Networks 43 3.2.3.1 PicoRadio 44 3.2.3.2 WINS 44 3.2.3.3 (lAMPS 44 3.3 A Practical Physical Layer For Wireless Sensor Networks 44 3.3.1 Cost 44 3.3.2 Power 47 3.3.2.1 Power Source 47 3.3.2.2 Power Consumption 48 3.4 Simulations and Results 52 3.4.1 Simulations 52 3.4.2 Results 55 3.5 Conclusion 59 References 59
Chapter 4 The Data Link Layer ,. 63
4.1 Introduction 63 4.2 Medium Access Control Techniques 64 4.2.1 ALOHA 65 4.2.2 Carrier Sense Multiple Access (CSMA) 65 4.2.3 Polling 67 4.2.4 Access Techniques in Wireless Sensor Networks 69 4.2.4.1 WINS 69 4.2.4.2 PicoRadio 70 4.2.4.3 Others 70 4.3 The Mediation Device (MD) 71 4.3.1 The MD Protocol 71 4.3.2 The Distributed MD Protocol 74 4.3.3 "Emergency" Mode 76 4.3.4 Channel Access 77 4.4 System Analysis and Simulation 78 4.4.1 Duty Cycle 78
4.4.2 Latency 79 4.5 Conclusion 81 References 82
Chapter 5 The Network Layer 85
5.1 Introduction 85 5.2 Some Network Design Examples 85 5.2.1 Structure 85 5.2.2 Routing 88 5.3 A Wireless Sensor Network Design Employing a Cluster
Tree Architecture 91 5.3.1 Network Design 92 5.3.2 Network Association 94 5.3.3 Network Maintenance 97 5.3.4 Routing 98 5.4 Simulations 98 5.5 Results 102
5.5.1 Throughput (Cumulative Percentage of Messages
Arriving at the DD versus Time) 102 5.5.2 Throughput (Cumulative Percentage of Messages
Arriving at the DD versus Node Level) 102 5.5.3 Average Message Transmission Time 103 5.5.4 Average Message Latency versus Node Level 104 5.5.5 Packet Collisions versus Time 105 5.5.6 Duty Cycle 106 5.5.7 Duty Cycle versus Level 106 5.5.8 Message Latency versus MD Period 108 5.5.9 Maximum Network Throughput versus MD Period 108 5.5.10 Maximum Network Throughput versus Node Density 108 5.6 Conclusion 110 References 110
Chapter 6 Practical Implementation Issues 115
6.1 Introduction 115 6.2 The Partitioning Decision 116 6.3 Transducer Interfaces 126 6.3.1 Integrated Sensors 126 6.3.2 The External Interface 127 6.4 Time Base Accuracy and Average Power Consumption 130 6.5 Conclusion 135 References 135
Chapter 7 Power Management 137
7.1 Introduction 137 7.2 Power Sources 138
Contents
7.2.1 Mains 139 7.2.2 Batteries 140 7.2.2.1 Lifetime 140 7.2.2.2 "Low Battery" Detection 140 7.2.2.3 "Low Battery" Alarm 146 7.2.2.4 Choice of Cell Chemistry 147 7.2.3 Energy Scavenging 149 7.2.3.1 Photovoltaic Cells 152 7.2.3.2 Mechanical Vibration 153 7.2.3.3 Other Scavengable Energy Sources 157 7.3 Loads 161 7.3.1 Power Consumption of Analog Circuits 162 7.3.2 Power Consumption of Digital Logic 165 7.3.3 Power Consumption of Other Loads 172 7.4 Voltage Converters and Regulators 174 7.4.1 Types of Voltage Converters 174 7.4.2 Voltage Conversion Strategy 181 7.5 Power Management Strategy 184 7.6 Conclusion 185 References 186
Chapter 8 Antennas and the Definition of RF Performance 191
8.1 Introduction 191 8.2 Antennas 191 8.2.1 Antenna Characteristics 191 8.2.2 Efficiency and Antenna Placement 193 8.2.3 Bandwidth •. 199 8.2.4 Antenna Design Choices 201 8.3 RF Performance Definition and Measurement 203 8.3.1 Definition and Measurement 203 8.3.2 Production Issues 212 8.4 Conclusion 215 References 216
Chapter 9 Electromagnetic Compatibility 219
9.1 Introduction 219 9.2 EMC: The Problem 219 9.3 Examples of Self-Interference 220 9.4 The Physics Associated with EMC Problems 223 9.4.1 The Wideband Spectral View 223 9.4.2 The Narrowband Spectral View 232 9.4.3 Victim Circuits in Receivers 233 9.4.3.1 The Zero-IF Receiver 233 9.4.3.2 The Low-IF Receiver 234 9.4.3.3 The Superheterodyne Receiver 235
9.4.4 Scope of the Problem 236 9.4.4.1 Digital-RF Isolation Needed 236 9.4.5 Coupling Mechanisms 236 9.4.5.1 "Radiated" Coupling 236 9.4.5.2 "Conducted" Coupling 243 9.4.6 Avoiding Coupling Problems 244 9.4.6.1 System Level 245 9.4.6.2 Integrated Circuit Level 247 9.4.6.3 Circuit Board Level 249 9.5 Principles of Proper Layout 255 9.5.1 There is No Ground 255 9.5.2 There is Only Return Current 255 9.6 The Layout Process 256
9.6.1 Things to Look for After the Schematics Are Done
but Before the Layouts Are Started 256 9.6.1.1 High-Frequency Voltages and Currents 256 9.6.1.2 Antenna Placement 260 9.6.1.3 Power Source Placement 260 9.6.1.4 Sensor Placement 260 9.6.1.5 Placement of Oscillators 260 9.6.1.6 RF Filters, Low-Noise Amplifiers (LNAs), and Power Amplifiers 261 9.6.2 EMC-Aware Layout Procedure 262 9.7 Detective/Corrective Techniques 263 9.7.1 The "Hole in the Bucket" Principle 264 9.7.2 Substitution 264 9.7.3 Software to Control Specific MCU Functions 264 9.7.4 Physical Separation 265 9.7.5 The Fallacy of Shields 265 9.7.6 Get to Know the IC Designer 265 9.7.7 Simulation 265 9.8 Conclusion 266 References 266
Chapter 10 Electrostatic Discharge 269
10.1 Introduction 269 10.2 The Problem 269 10.2.1 Examples 269 10.2.2 Failure Modes 271 10.3 Physical Properties of the Electrostatic Discharge 272 10.3.1 The Triboelectric Effect 273 10.3.2 Air Breakdown 273 10.3.3 Charge Redistribution 274 10.4 The Effects of ESD on ICs 275 10.5 Modeling and Test Standards 276
Contents
10.5.1 The Double Exponential Pulse 276 10.5.2 Human Body, Machine, and Charged Device Models 277 10.5.3 Detailed Requirements of an ESD Standard 278 10.5.4 Performance Standards 279 10.6 Product Design to Minimize ESD Problems 279
10.6.1 Prevent Discharges from Entering or Exiting
the Housing 279 10.6.1.1 Avoid Holes in the Housing 279 10.6.1.2 Locate Circuit Boards and the Metal on Them
Away from Housing Holes 280 10.6.1.3 Eliminate Metal Points and Burrs 282 10.6.2 Once Inside, Design Paths for the Discharge to Travel 282 10.6.3 Reaching the Integrated Circuit 284 10.6.4 Once an ESD Event Occurs, Limit Discernable Effects 288 10.7 Conclusion 290 References 291
Chapter 11 Wireless Sensor Network Standards 293
11.1 Introduction 293 11.2 The IEEE 802.15.4 Low-Rate WPAN Standard 293 11.3 The ZigBee Alliance 297 11.4 The IEEE 1451.5 Wireless Smart Transducer
Interface Standard 298 References 299
Chapter 12 Summary and Opportunities for Future Development 301
12.1 Summary 301 12.2 Opportunities for Future Development 304 References 307
Appendix A Signal Processing Worksystem (SPW) 309 Appendix B WinneuRFon 311
B.I Introduction 311 B.2 Motivation 311 B.3 System Requirements 312 B.4 Supported Features 313 B.5 Current Status and Achievement 313 B.6 Simulation Method and More Potential Functionalities 316 B.7 Proposal for Future Work 318 B.8 Summary 318
Appendix C An Example Wireless Sensor Network
About the Author 325 Index 327
