Preface xiii
About the Companion Website xv
1 Introduction 1
1.1 History of Wearable Technology 1
1.2 Introduction to BSN Technology 2
1.3 BSN Architecture 7
1.4 Layout of the Book 10
References 11
2 Physical, Physiological, Biological, and Behavioural States of the Human Body 17
2.1 Introduction 17
2.2 Physical State of the Human Body 17
2.3 Physiological State of Human Body 19
2.4 Biological State of Human Body 23
2.5 Psychological and Behavioural State of the Human Body 24
2.6 Summary and Conclusions 30
References 31
3 Physical, Physiological, and Biological Measurements 35
3.1 Introduction 35
3.2 Wearable Technology for Gait Monitoring 35
3.2.1 Accelerometer and Its Application to Gait Monitoring 36
3.2.1.1 How Accelerometers Operate 37
3.2.1.2 Accelerometers in Practice 39
3.2.2 Gyroscope and IMU 40
3.2.3 Force Plates 41
3.2.4 Goniometer 41
3.2.5 Electromyography 41
3.2.6 Sensing Fabric 42
3.3 Physiological Sensors 42
3.3.1 Multichannel Measurement of the Nerves Electric Potentials 42
3.3.2 Other Sensors 45
3.4 Biological Sensors 48
3.4.1 The Structures of Biological Sensors – The Principles 48
3.4.2 Emerging Biosensor Technologies 51
3.5 Conclusions 51
References 53
4 Ambulatory and Popular Sensor Measurements 59
4.1 Introduction 59
4.2 Heart Rate 59
4.2.1 HR During Physical Exercise 60
4.3 Respiration 62
4.4 Blood Oxygen Saturation Level 67
4.5 Blood Pressure 70
4.5.1 Cuffless Blood Pressure Measurement 71
4.6 Blood Glucose 72
4.7 Body Temperature 73
4.8 Commercial Sensors 74
4.9 Conclusions 75
References 76
5 Polysomnography and Sleep Analysis 83
5.1 Introduction 83
5.2 Polysomnography 84
5.3 Sleep Stage Classification 85
5.3.1 Sleep Stages 85
5.3.2 EEG-Based Classification of Sleep Stages 86
5.3.2.1 Time Domain Features 86
5.3.2.2 Frequency Domain Features 87
5.3.2.3 Time-frequency Domain Features 87
5.3.2.4 Short-time Fourier Transform 88
5.3.2.5 Wavelet Transform 88
5.3.2.6 Matching Pursuit 88
5.3.2.7 Empirical Mode Decomposition 89
5.3.2.8 Nonlinear Features 89
5.3.3 Classification Techniques 90
5.3.3.1 Using Neural Networks 90
5.3.3.2 Application of CNNs 92
5.3.4 Sleep Stage Scoring Using CNN 94
5.4 Monitoring Movements and Body Position During Sleep 96
5.5 Conclusions 99
References 100
6 Noninvasive, Intrusive, and Nonintrusive Measurements 107
6.1 Introduction 107
6.2 Noninvasive Monitoring 107
6.3 Contactless Monitoring 109
6.3.1 Remote Photoplethysmography 109
6.3.1.1 Derivation of Remote PPG 110
6.3.2 Spectral Analysis Using Autoregressive Modelling 111
6.3.3 Estimation of Physiological Parameters Using Remote PPG 114
6.3.3.1 Heart Rate Estimation 114
6.3.3.2 Respiratory Rate Estimation 116
6.3.3.3 Blood Oxygen Saturation Level Estimation 117
6.3.3.4 Pulse Transmit Time Estimation 118
6.3.3.5 Video Pre-processing 119
6.3.3.6 Selection of Regions of Interest 120
6.3.3.7 Derivation of the rPPG Signal 120
6.3.3.8 Processing rPPG Signals 120
6.3.3.9 Calculation of rPTT/dPTT 121
6.4 Implantable Sensor Systems 122
6.5 Conclusions 123
References 124
7 Single and Multiple Sensor Networking for Gait Analysis 129
7.1 Introduction 129
7.2 Gait Events and Parameters 129
7.2.1 Gait Events 129
7.2.2 Gait Parameters 130
7.2.2.1 Temporal Gait Parameters 130
7.2.2.2 Spatial Gait Parameters 132
7.2.2.3 Kinetic Gait Parameters 133
7.2.2.4 Kinematic Gait Parameters 133
7.3 Standard Gait Measurement Systems 135
7.3.1 Foot Plantar Pressure System 135
7.3.2 Force-plate Measurement System 135
7.3.3 Optical Motion Capture Systems 137
7.3.4 Microsoft Kinect Image and Depth Sensors 138
7.4 Wearable Sensors for Gait Analysis 140
7.4.1 Single Sensor Platforms 140
7.4.2 Multiple Sensor Platforms 141
7.5 Gait Analysis Algorithms Based on Accelerometer/Gyroscope 143
7.5.1 Estimation of Gait Events 143
7.5.2 Estimation of Gait Parameters 144
7.5.2.1 Estimation of Orientation 144
7.5.2.2 Estimating Angles Using Accelerometers 146
7.5.2.3 Estimating Angles Using Gyroscopes 147
7.5.2.4 Fusing Accelerometer and Gyroscope Data 148
7.5.2.5 Quaternion Based Estimation of Orientation 148
7.5.2.6 Step Length Estimation 150
7.6 Conclusions 152
References 152
8 Popular Health Monitoring Systems 157
8.1 Introduction 157
8.2 Technology for Data Acquisition 157
8.3 Physiological Health Monitoring Technologies 158
8.3.1 Predicting Patient Deterioration 158
8.3.2 Ambient Assisted Living: Monitoring Daily Living Activities 163
8.3.3 Monitoring Chronic Obstructive Pulmonary Disease Patients 164
8.3.4 Movement Tracking and Fall Detection/Prevention 165
8.3.5 Monitoring Patients with Dementia 166
8.3.6 Monitoring Patients with Parkinson’s Disease 168
8.3.7 Odour Sensitivity Measurement 172
8.4 Conclusions 174
References 174
9 Machine Learning for Sensor Networks 183
9.1 Introduction 183
9.2 Clustering Approaches 187
9.2.1 k-means Clustering Algorithm 187
9.2.2 Iterative Self-organising Data Analysis Technique 188
9.2.3 Gap Statistics 188
9.2.4 Density-based Clustering 189
9.2.5 Affinity-based Clustering 190
9.2.6 Deep Clustering 190
9.2.7 Semi-supervised Clustering 191
9.2.7.1 Basic Semi-supervised Techniques 191
9.2.7.2 Deep Semi-supervised Techniques 191
9.2.8 Fuzzy Clustering 192
9.3 Classification Algorithms 193
9.3.1 Decision Trees 193
9.3.2 Random Forest 194
9.3.3 Linear Discriminant Analysis 194
9.3.4 Support Vector Machines 195
9.3.5 k-nearest Neighbour 201
9.3.6 Gaussian Mixture Model 201
9.3.7 Logistic Regression 202
9.3.8 Reinforcement Learning 202
9.3.9 Artificial Neural Networks 203
9.3.9.1 Deep Neural Networks 204
9.3.9.2 Convolutional Neural Networks 205
9.3.9.3 Recent DNN Approaches 207
9.3.10 Gaussian Processes 208
9.3.11 Neural Processes 208
9.3.12 Graph Convolutional Networks 209
9.3.13 Naïve Bayes Classifier 209
9.3.14 Hidden Markov Model 210
9.3.14.1 Forward Algorithm 212
9.3.14.2 Backward Algorithm 212
9.3.14.3 HMM Design 212
9.4 Common Spatial Patterns 213
9.5 Applications of Machine Learning in BSNs and WSNs 216
9.5.1 Human Activity Detection 216
9.5.2 Scoring Sleep Stages 217
9.5.3 Fault Detection 218
9.5.4 Gas Pipeline Leakage Detection 218
9.5.5 Measuring Pollution Level 218
9.5.6 Fatigue-tracking and Classification System 218
9.5.7 Eye-blink Artefact Removal from EEG Signals 219
9.5.8 Seizure Detection 219
9.5.9 BCI Applications 219
9.6 Conclusions 219
References 220
10 Signal Processing for Sensor Networks 229
10.1 Introduction 229
10.2 Signal Processing Problems for Sensor Networks 230
10.3 Fundamental Concepts in Signal Processing 231
10.3.1 Nonlinearity of the Medium 231
10.3.2 Nonstationarity 232
10.3.3 Signal Segmentation 233
10.3.4 Signal Filtering 236
10.4 Mathematical Data Models 237
10.4.1 Linear Models 237
10.4.1.1 Prediction Method 237
10.4.1.2 Prony’s Method 238
10.4.1.3 Singular Spectrum Analysis 240
10.4.2 Nonlinear Modelling 242
10.4.3 Gaussian Mixture Model 243
10.5 Transform Domain Signal Analysis 245
10.6 Time-frequency Domain Transforms 245
10.6.1 Short-time Fourier Transform 245
10.6.2 Wavelet Transform 246
10.6.2.1 Continuous Wavelet Transform 246
10.6.2.2 Examples of Continuous Wavelets 247
10.6.2.3 Discrete Time Wavelet Transform 247
10.6.3 Multiresolution Analysis 248
10.6.4 Synchro-squeezing Wavelet Transform 249
10.7 Adaptive Filtering 250
10.8 Cooperative Adaptive Filtering 251
10.8.1 Diffusion Adaptation 252
10.9 Multichannel Signal Processing 254
10.9.1 Instantaneous and Convolutive BSS Problems 255
10.9.2 Array Processing 257
10.10 Signal Processing Platforms for BANs 258
10.11 Conclusions 259
References 260
11 Communication Systems for Body Area Networks 267
11.1 Introduction 267
11.2 Short-range Communication Systems 271
11.2.1 Bluetooth 271
11.2.2 Wi-Fi 272
11.2.3 ZigBee 272
11.2.4 Radio Frequency Identification Devices 273
11.2.5 Ultrawideband 273
11.2.6 Other Short-range Communication Methods 274
11.2.7 RF Modules Available in Market 275
11.3 Limitations, Interferences, Noise, and Artefacts 275
11.4 Channel Modelling 276
11.4.1 BAN Propagation Scenarios 276
11.4.1.1 On-body Channel 276
11.4.1.2 In-body Channel 277
11.4.1.3 Off-body Channel 277
11.4.1.4 Body-to-body (or Interference) Channel 278
11.4.2 Recent Approaches to BAN Channel Modelling 278
11.4.3 Propagation Models 279
11.4.4 Standards and Guidelines 283
11.5 BAN-WSN Communications 284
11.6 Routing in WBAN 285
11.6.1 Posture-based Routing 285
11.6.2 Temperature-based Routing 286
11.6.3 Cross-layer Routing 287
11.6.4 Cluster-based Routing 288
11.6.5 QoS-based Routing 289
11.7 BAN-building Network Integration 290
11.8 Cooperative BANs 290
11.9 BAN Security 291
11.10 Conclusions 292
References 292
12 Energy Harvesting Enabled Body Sensor Networks 301
12.1 Introduction 301
12.2 Energy Conservation 302
12.3 Network Capacity 302
12.4 Energy Harvesting 303
12.5 Challenges in Energy Harvesting 304
12.6 Types of Energy Harvesting 307
12.6.1 Harvesting Energy from Kinetic Sources 308
12.6.2 Energy Sources from Radiant Sources 312
12.6.3 Energy Harvesting from Thermal Sources 312
12.6.4 Energy Harvesting from Biochemical and Chemical Sources 313
12.7 Topology Control 315
12.8 Typical Energy Harvesters for BSNs 317
12.9 Predicting Availability of Energy 318
12.10 Reliability of Energy Storage 319
12.11 Conclusions 320
References 321
13 Quality of Service, Security, and Privacy for Wearable Sensor Data 325
13.1 Introduction 325
13.2 Threats to a BAN 326
13.2.1 Denial-of-service 326
13.2.2 Man-in-the-middle Attack 327
13.2.3 Phishing and Spear Phishing Attacks 327
13.2.4 Drive-by Attack 327
13.2.5 Password Attack 328
13.2.6 SQL Injection Attack 328
13.2.7 Cross-site Scripting Attack 328
13.2.8 Eavesdropping 328
13.2.9 Birthday Attack 329
13.2.10 Malware Attack 329
13.3 Data Security and Most Common Encryption Methods 330
13.3.1 Data Encryption Standard (DES) 331
13.3.2 Triple DES 331
13.3.3 Rivest–Shamir–Adleman (RSA) 331
13.3.4 Advanced Encryption Standard (AES) 332
13.3.5 Twofish 334
13.4 Quality of Service (QoS) 334
13.4.1 Quantification of QoS 335
13.4.1.1 Data Quality Metrics 335
13.4.1.2 Network Quality Related Metrics 335
13.5 System Security 337
13.6 Privacy 339
13.7 Conclusions 339
References 340
14 Existing Projects and Platforms 345
14.1 Introduction 345
14.2 Existing Wearable Devices 347
14.3 BAN Programming Framework 348
14.4 Commercial Sensor Node Hardware Platforms 348
14.4.1 Mica2/MicaZ Motes 348
14.4.2 TelosB Mote 349
14.4.3 Indriya-Zigbee Based Platform 350
14.4.4 IRIS 350
14.4.5 iSense Core Wireless Module 351
14.4.6 Preon32 Wireless Module 351
14.4.7 Wasp Mote 352
14.4.8 WiSense Mote 352
14.4.9 panStamp NRG Mote 354
14.4.10 Jennic JN5139 354
14.5 BAN Software Platforms 355
14.5.1 Titan 355
14.5.2 CodeBlue 355
14.5.3 RehabSPOT 356
14.5.4 SPINE and SPINE2 356
14.5.5 C-SPINE 356
14.5.6 MAPS 356
14.5.7 DexterNet 356
14.6 Popular BAN Application Domains 356
14.7 Conclusions 359
References 359
15 Conclusions and Suggestions for Future Research 363
15.1 Summary 363
15.2 Future Directions in BSN Research 363
15.2.1 Smart Sensors: Intelligent, Biocompatible, and Wearable 364
15.2.2 Big Data Problem 366
15.2.3 Data Processing and Machine Learning 366
15.2.4 Decentralised and Cooperative Networks 367
15.2.5 Personalised Medicine Through Personalised Technology 367
15.2.6 Fitting BSN to 4G and 5G Communication Systems 367
15.2.7 Emerging Assistive Technology Applications 368
15.2.8 Solving Problems with Energy Harvesting 368
15.2.9 Virtual World 368
15.3 Conclusions 369
References 369
Index 373
