Visible Light Communications

ZHAOCHENG WANG, PhD, is a Professor at the Department of Electronic Engineering at Tsinghua University, China. Dr. Wang previously published Millimeter Wave Communication Systems with Wiley-IEEE Press. QI WANG, PhD, is a Research Fellow at the School of Electronics and Computer Science at University of Southampton, United Kingdom. WEI HUANG, PhD, is an academic member of the School of Information Science and Technology, University of Science and Technology of China. ZHENGYUAN XU, PhD, is a Professor at the School of Information Science and Technology, University of Science and Technology of China

Preface ix 1 Introduction to Visible Light Communications 1 1.1 History 1 1.2 Advantages and applications 4 1.3 Overview of modulation and signal processing 6 1.4 Standards 10 2 Visible Light Communications: Channel and Capacity 17 2.1 LED characteristics 17 2.1.1 Operation principles 19 2.1.2 LED nonlinearity 21 2.2 LED lighting constraints 23 2.2.1 Dimming control 23 2.2.2 Chromaticity control 25 2.2.3 Flicker-free communication 26 2.3 Photodiode characteristics 27 2.4 Propagation links 29 2.4.1 LOS link 31 2.4.2 NLOS link 32 2.5 Noise in VLC systems 33 2.6 Channel capacity 35 2.6.1 Channel models 36 2.6.2 Capacity bounds for free-space optical intensity channel 38 2.6.3 Capacity bounds for discrete-time Poisson channel 47 2.6.4 Capacity bounds for improved free-space intensity channel 50 2.7 Conclusion 53 3 Single Carrier/Carrierless Modulation and Coding 57 3.1 Pulse amplitude modulation 57 3.2 Pulse position modulation 62 3.3 Carrierless amplitude phase modulation 68 3.3.1 Principles of CAP 69 3.3.2 Multidimensional CAP 73 3.4 Modulation and coding schemes for dimmable VLC 77 3.4.1 Modulation schemes for dimmable VLC 78 3.4.2 Coding schemes for dimmable VLC 80 3.5 Conclusion 82 4 Multicarrier Modulation 89 4.1 Optical OFDM for visible light communications 90 4.1.1 DC-biased optical OFDM 90 4.1.2 ACO-OFDM and PAM-DMT 93 4.1.3 Unipolar OFDM 97 4.1.4 Performance comparison 98 4.2 Performance enhancement for optical OFDM 99 4.2.1 DC bias and scaling optimization 100 4.2.2 LED nonlinearity mitigation 103 4.2.3 PAPR reduction 107 4.3 Spectrum- and power-efficient optical OFDM 111 4.3.1 Hybrid optical OFDM 111 4.3.2 Enhanced U-OFDM 118 4.3.3 Layered ACO-OFDM 121 4.4 Optical OFDM under lighting constraints 131 4.4.1 Pulse width modulation 133 4.4.2 Reverse polarity optical OFDM 136 4.4.3 Asymmetrical hybrid optical OFDM 137 4.5 Conclusion 142 5 Multicolor Modulation 147 5.1 Color shift keying 147 5.1.1 Constellation 148 5.1.2 Color calibration 151 5.1.3 Constellation optimization 152 5.1.4 CSK with Quad-LED 155 5.2 CSK with coded modulation 156 5.3 Wavelength division multiplexing with predistorion 159 5.3.1 System model 160 5.3.2 Receiver-side predistortion 161 5.3.3 Performance evaluation 164 5.4 Conclusion 166 6 Optical MIMO 169 6.1 Non-imaging optical MIMO techniques 170 6.1.1 Channel response 170 6.1.2 Optical MIMO techniques 171 6.1.3 Performance comparison 175 6.2 Imaging optical MIMO techniques 178 6.3 Multiuser precoding techniques 180 6.4 Optical MIMO-OFDM 190 6.4.1 DCO-OFDM-based MU-MIMO VLC 193 6.4.2 ACO-OFDM-based MU-MIMO VLC 194 6.4.3 Performance evaluation 195 6.5 Conclusion 197 7 Signal Processing and Optimization 201 7.1 Sum-rate maximization for the multi-chip-based VLC system 201 7.1.1 System model 202 7.1.2 Constraints on illumination and communication 203 7.1.3 Sum-rate maximization 205 7.1.4 Performance evaluation 208 7.2 Heterogeneous VLC-WiFi optimization 212 7.2.1 System model 213 7.2.2 Efficient VHO scheme 214 7.2.3 Performance evaluation 219 7.3 Signal estimation and modulation design for VLC with SDGN 223 7.3.1 Signal estimation for VLC with SDGN 223 7.3.2 Suboptimal estimation for VLC with SDGN 228 7.3.3 Efficient signal design for VLC with SDGN 230 7.4 Conclusion 236 8 Optical Camera Communication: Fundamentals 239 8.1 Why OCC 239 8.1.1 Wide spectrum 240 8.1.2 Image-sensor-based receiver 240 8.1.3 Advantages of image sensor receiver 241 8.1.4 Challenges for OCC implementation 244 8.2 OCC applications: beyond imaging 246 8.2.1 Indoor localization 246 8.2.2 Intelligent transportation 249 8.2.3 Screen-camera communication 250 8.2.4 Privacy protection 251 8.3 Fundamentals of OCC 252 8.3.1 Optical imaging system 252 8.3.2 Image sensor architecture 253 8.3.3 Noise characteristics in the image-sen