Optical Wireless Communications

Transcription

1 Optical Wireless Communications System and Channel Modelling with MATLAB Z. Ghassemlooy W. Popoola S. Rajbhandari W CRC Press Taylor & Francis Croup Boca Raton London New York CRC Press is an imprint of the Taylor & Francis Croup, an informa business

2 Preface Authors List of Figures List of Tables Abbreviations xv xix xxiii xxxvii xxxix Chapter 1 Introduction: Optical Wireless Communication Systems Wireless Access Schemes A Brief History of OWC OWC/Radio Comparison Link Configuration OWC Application Areas Safety and Regulations Maximum Permissible Exposures OWC Challenges 25 References 30 Chapter 2 Optical Sources and Detectors Light Sources Light-Emitting Diode LED Structure Planar and Dome LED Edge-Emitting LED LED Efficiencies Internal Quantum Efficiency External Quantum Efficiency Power Efficiency Luminous Efficiency LED Modulation Bandwidth The Laser Operating Principle of a Laser Stimulated Emission Population Inversion Optical Feedback and Laser Oscillation Basic Semiconductor Laser Structure The Structure of Common Laser Types Fabry-Perot Laser Distributed Feedback Laser 54 vii

3 Vertical-Cavity Surface-Emitting Laser Superluminescent Diodes Comparison of LED and Laser Diodes Photodetectors PIN Photodetector APD Photodetector Photodetection Techniques Direct Detection Coherent Detection Heterodyne Detection Homodyne Detection Photodetection Noise Photon Fluctuation Noise Dark Current and Excess Noise Background Radiation Thermal Noise Intensity Noise Signal-to-Noise Ratio Optical Detection Statistics 72 References 74 er 3 Channel Modelling Indoor Optical Wireless Communication Channel LOS Propagation Model Non-LOS Propagation Model Ceiling Bounce Model Hayasaka-Ito Model Spherical Model Artificial Light Interference Incandescent Lamp Fluorescent Lamp Driven by Conventional Ballast Fluorescent Lamp Model Outdoor Channel Atmospheric Channel Loss Fog and Visibility Ill Beam Divergence Optical and Window Loss Pointing Loss The Atmospheric Turbulence Models Log-Normal Turbulence Model Spatial Coherence in Weak Turbulence Limit of Log-Normal Turbulence Model The Gamma-Gamma Turbulence Model The Negative Exponential Turbulence Model 142

4 * Atmospheric Effects on OWC Test Bed Demonstration of Scintillation Effect on Data Carrying Optical Radiation 146 References 154 Chapter 4 Modulation Techniques Introduction Analogue Intensity Modulation Digital Baseband Modulation Techniques Baseband Modulations On-Off Keying Error Performance on Gaussian Channels Pulse Position Modulation Error Performance on Gaussian Channels PPM Variants Multilevel PPM Differential PPM Differential Amplitude Pulse Position Modulation Pulse Interval Modulation Error Performance on Gaussian Channels DPIM with No Guard Band DPIM with One Guard Slot Optimum Threshold Level Dual-Header PIM (DH-PIM) Spectral Characteristics Error Performance on Gaussian Channels Multilevel DPIM Comparisons of Baseband Modulation Schemes Power Efficiency Transmission Bandwidth Requirements Transmission Capacity Transmission Rate Peak-to-Average Power Ratio Subcarrier Intensity Modulation Orthogonal Frequency Division Multiplexing Optical Polarization Shift Keying Binary PolSK Bit Error Rate Analysis MPolSK Differential Circle Polarization Shift Keying Error Probability Analysis 247 Appendix 4.A A. 1 Derivation of Slot Autocorrelation Function of DPIM(IGS) 248

5 x Contents Appendix 4.B B.1 PSDofDH-PIM B.1.1 Fourier Transform of DH-PIM B.1.2 Power Spectral Density of DH-PIM B. 1.3 Further Discussion on the PSD Expression 260 References 261 Chapter 5 System Performance Analysis: Indoor Effect of Ambient Light Sources on Indoor OWC Link Performance Effect of FLI without Electrical High-Pass Filtering Matched Filter Receiver Effect of Baseline Wander without FLI Effect of FLI with Electrical High-Pass Filtering Wavelet Analysis The Continuous Wavelet Transform The Discrete Wavelet Transform DWT-Based Denoising Comparative Study of DWT and HPF Experimental Investigations Link Performance for Multipath Propagation OOK PPM DPIM Mitigation Techniques Filtering Equalization The Zero Forcing Equalizer Minimum Mean Square Error Equalizer Decision Feedback Equalizer Equalization as a Classification Problem Introduction to Artificial Neural Network Neuron ANN Architectures Training Network Backpropagation Learning The ANN-Based Adaptive Equalizer Comparative Study of the ANN- and FIR-Based Equalizers Diversity Techniques 341 References 342

6 Chapter 6 FSO Link Performance under the Effect of Atmospheric Turbulence On-Off Keying OOK in a Poisson Atmospheric Optical Channel OOK in a Gaussian Atmospheric Optical Channel Pulse Position Modulation Subcarrier Intensity Modulation SIM Generation and Detection SIM-FSO Performance in Log-Normal Atmospheric Channel Bit Error Probability Analysis of SIM-FSO BPSK-Modulated Subcarrier M-Ary PSK-Modulated Subcarrier DPSK-Modulated Subcarrier Multiple SIM Performance Analysis Outage Probability in Log-Normal Atmospheric Channels SIM-FSO Performance in Gamma-Gamma and Negative Exponential Atmospheric Channels Outage Probability in Negative Exponential Model Atmospheric Channels Atmospheric Turbulence-Induced Penalty 384 Appendix 6.A 388 Appendix 6.B B.1 MATLAB Scripts for Sections 6.3.2, and B.1.1 Section B.1.2 Sections and References 394 xi Chapter 7 Outdoor OWC Links with Diversity Techniques Atmospheric Turbulence Mitigation Techniques Receiver Diversity in Log-Normal Atmospheric Channels Maximum Ratio Combining Equal Gain Combining Selection Combining Effect of Received Signal Correlation on Error Performance Outage Probability with Receiver Diversity in a Log-Normal Atmospheric Channel 408

7 xii Contents 7.3 Transmitter Diversity in a Log-Normal Atmospheric Channel Transmitter-Receiver Diversity in a Log-Normal Atmospheric Channel Results and Discussions of SIM-FSO with Spatial Diversity in a Log-Normal Atmospheric Channel SIM-FSO with Receiver Diversity in Gamma-Gamma and Negative Exponential Atmospheric Channels BER and Outage Probability of BPSK-SIM with Spatial Diversity BER and Outage Probability of DPSK-SIM in Negative Exponential Channels Terrestrial Free Space Optical Links with Subcarrier Time Diversity Error Performance with STDD Error Performance of Short-Range Links Error Performance of Long-Range Links Results and Discussion for Short-Range Links Results and Discussion for Long-Range Links Aperture Averaging Plane Wave Spherical Wave Gaussian Beam Wave 434 Appendix 7.A A. 1 Sum of Log-Normal Distribution Mean and Variance Calculation 435 Appendix 7.B B. 1 PDF of I mu = max{7, }^ for Log-Normal-Distributed Variables 437 Appendix 7.C C.1 PDF of I mm = max {/,-}j^ for Negative Exponential Distributed Variables 438 References 438 Chapter 8 Visible Light Communications Introduction System Description VLC System Model SNR Analysis Channel Delay Spread 464

8 xiii 8.3 System Implementations Bit Angle Modulation Pulse Modulation Schemes PWM with Discrete Multitone Modulation Multilevel PWM-PPM PWM with NRZ-OOK Multiple-Input-Multiple-Output VLC Home Access Network 486 References 493 Index 497