Optical Wireless Communication

Contents
1 Optical Wireless Communication System
	1.1 System Model of Optical Wireless Communication
		1.1.1 Transmitter
		1.1.2 Receiver
		1.1.3 Channel
	1.2 Laser Light Source
		1.2.1 Principles of a Laser Diode
		1.2.2 Characteristics of a Laser Diode
		1.2.3 Nonlinearity Correction
	1.3 Device Response Characteristics
		1.3.1 Response Characteristics of a Semiconductor Laser
		1.3.2 Response Characteristics of a PIN Photodetector
	1.4 Surface Plasmon Polarization
		1.4.1 Effect of Different Incident Light Directions on the Light Absorption Performance of Silicon Substrates
		1.4.2 Electric Field Modulus Distribution on the x–z Cross Section of the Photodetector
	1.5 Signal Detection
		1.5.1 Direct Detection
		1.5.2 Direct Detection Limit
	1.6 Optical Amplifier
		1.6.1 Classification of Optical Amplifiers
		1.6.2 Erbium-Doped Fiber Amplifier
		1.6.3 Semiconductor Optical Amplifier
	1.7 Spatial Light to Fiber Coupling Technology
		1.7.1 Single Lens Coupling
		1.7.2 Array Coupling
		1.7.3 Special Fiber Coupling
	1.8 Optical Antenna and Telescope
		1.8.1 Refractor Telescope
		1.8.2 Reflecting Telescope
		1.8.3 Catadioptric Telescope
		1.8.4 Integrated Transceiver Optical Antenna
	1.9 Summary and Prospects
	1.10 Questions
	1.11 Exercises
	References
2 Coherent Optical Communication
	2.1 Basic Principles of Coherent Optical Communication
		2.1.1 Fundamentals
		2.1.2 Homodyne Detection
		2.1.3 Heterodyne Detection
		2.1.4 Detection of an Amplitude Modulated Signal
		2.1.5 Dual-Channel Balanced Detection
	2.2 Coherent Modulation and Demodulation
		2.2.1 Optical Modulation
		2.2.2 Coherent Demodulation
		2.2.3 System Performance
	2.3 Factors Affecting Detection Sensitivity
		2.3.1 Phase Noise
		2.3.2 Intensity Noise
		2.3.3 Polarization Noise
		2.3.4 Key Technologies of Coherent Optical Communication Systems
	2.4 Spatial Phase Conditions for Optical Heterodyne Detection
		2.4.1 Spatial Phase Difference Conditions
		2.4.2 Frequency Conditions
		2.4.3 Polarization Conditions
	2.5 Adaptive Optical Wavefront Correction
		2.5.1 Wavefront Distortion Correction System
		2.5.2 Wavefront Measurement and Correction
		2.5.3 Wavefront-Free Measurement System
	2.6 Summary and Prospects
	2.7 Questions
	2.8 Exercises
	References
3 Modulation, Demodulation, and Coding
	3.1 Modulation
		3.1.1 Basic Concepts
		3.1.2 Analog and Digital Modulation
		3.1.3 Direct and Indirect Modulation
		3.1.4 Internal and External Modulation
	3.2 External Modulation
		3.2.1 Electro-Optic Modulation
		3.2.2 Acousto-Optic Modulation
		3.2.3 Magneto-Optic Modulation
	3.3 Reverse Modulation
		3.3.1 Cat’s Eye Effect
		3.3.2 Principle of Reverse Modulation
		3.3.3 Cat’s Eye Reverse Modulation System
	3.4 Pulse-Like Position Modulation
		3.4.1 Pulse-Like Position Modulation
		3.4.2 Synchronization Technology
	3.5 Direct Drive of Light Source
		3.5.1 Single-Ended to Differential Converter
		3.5.2 Level Adjustment
		3.5.3 Laser Driver
		3.5.4 Principle of Optical Feedback
	3.6 Subcarrier Intensity Modulation
		3.6.1 Subcarrier Intensity Modulation
		3.6.2 BPSK Subcarrier Modulation
		3.6.3 FSK Subcarrier Modulation
		3.6.4 Intermodulation Distortion and Carrier-to-Noise Ratio
	3.7 Orthogonal Frequency-Division Multiplexing
		3.7.1 Basic Principles
		3.7.2 Implementation of Discrete Fourier Transform in OFDM
		3.7.3 Protection Interval and Cyclic Prefix
		3.7.4 Peak-to-Average Power Ratio and Its Reduction Method
	3.8 Space–Time Coding
		3.8.1 Evolution of Space–Time Coding
		3.8.2 Space–Time Coding in Optical Wireless Communication
		3.8.3 Space–Time Decoding in Optical Wireless Communication
	3.9 Channel Coding
		3.9.1 Channel Coding
		3.9.2 Linear Error Correction Code
		3.9.3 Convolutional Code
	3.10 Summary and Prospects
	3.11 Questions
	3.12 Exercises
	References
4 Atmospheric Channel, Channel Estimation, and Channel Equalization
	4.1 Atmospheric Attenuation
		4.1.1 Atmospheric Attenuation Coefficient and Transmittance
		4.1.2 Absorption and Scattering of Atmospheric Molecules
		4.1.3 Absorption and Scattering of Atmospheric Aerosol Particles
		4.1.4 Atmospheric Window
		4.1.5 Estimation of the Attenuation Coefficient
		4.1.6 Transfer Equation
	4.2 Atmospheric Turbulence Model
		4.2.1 Atmospheric Turbulence
		4.2.2 Atmospheric Turbulence Channel Mode
		4.2.3 Log-Normal Turbulence Model
		4.2.4 Gamma-Gamma Turbulence Model
		4.2.5 Negative Exponential Distributed Turbulence Model
		4.2.6 Atmospheric Structure Constant
		4.2.7 Bit Error Rate Caused by Atmospheric Turbulence
	4.3 Diversity Reception
		4.3.1 Maximum Ratio Combining
		4.3.2 Equal Gain Combining
		4.3.3 Selective Combining
	4.4 Channel Estimation
		4.4.1 Concept of Channel Estimation
		4.4.2 Least Squares Channel Estimation Algorithm
		4.4.3 MMSE Based Channel Estimation
	4.5 Channel Equalization
		4.5.1 ISI and Channel Equalization
		4.5.2 Time Domain Equalization
		4.5.3 Linear Equalization
	4.6 Impacts of Atmospheric Turbulence on BER
	4.7 Summary and Prospects
	4.8 Questions
	4.9 Exercises
	References
5 White LED Communication
	5.1 Light-Emitting Principle of LED
		5.1.1 White LEDs
		5.1.2 Light-Emitting Principle of LED
		5.1.3 Light-Emitting Principle of White LED
		5.1.4 Lighting Model of White LED
	5.2 Background Noise Model for Internet of Vehicle
	5.3 Multiplicative Noise Model
	5.4 Optimal Layout of Light Source
	5.5 Indoor Visible Light Channel
	5.6 Receiver and Detection Technology
		5.6.1 Receiver Front End
		5.6.2 Receiving Array Design
	5.7 Uplink of Visible Light Communication
		5.7.1 Radio Frequency Uplink
		5.7.2 Infrared Uplink
		5.7.3 Laser Uplink
		5.7.4 Visible Light Uplink
		5.7.5 Isomorphic Uplink
	5.8 Visible Light Communication Positioning
		5.8.1 Received Optical Signal Strength Positioning
		5.8.2 Fingerprint Identification Positioning
		5.8.3 LED Identity Positioning
		5.8.4 Visible Light Imaging Positioning
	5.9 Summary and Prospects
	5.10 Questions
	5.11 Exercises
	References
6 Underwater Laser Communication
	6.1 Overview of Underwater Laser Communication
	6.2 Underwater Laser Communication System
		6.2.1 Principle of Underwater Laser Communication
		6.2.2 Underwater Channel
		6.2.3 Characteristics of Underwater Laser Communication
	6.3 Submarine Laser Communication
		6.3.1 Forms of Submarine Laser Communication
		6.3.2 Transmission of Each Dielectric Layer
		6.3.3 Time Spreading
		6.3.4 Energy Equation
		6.3.5 Trends of Submarine Laser Communication
	6.4 Summary and Prospects
	6.5 Questions
	6.6 Exercises
	References
7 Ultraviolet Communication
	7.1 UV Light and Its Channel Characteristics
		7.1.1 UV Light
		7.1.2 Characteristics of UV Light
		7.1.3 UV Atmospheric Channel
		7.1.4 Characteristics of UV Atmospheric Channel
	7.2 Characteristics of NLOS UV Transmission
		7.2.1 Ellipsoid Coordinate System
		7.2.2 UV Scattering Communication
		7.2.3 NLOS Scattering Characteristics
	7.3 Solar-Blind UV NLOS Communication Network
		7.3.1 Wireless Mesh Communication Network
		7.3.2 Wireless UV Mesh Communication Network
	7.4 Summary and Prospects
	7.5 Questions
	7.6 Exercises
	References
8 Acquisition, Aiming, and Tracking Technology
	8.1 Acquisition, Pointing, and Tracking System
		8.1.1 Concepts
		8.1.2 Operating Principle
	8.2 Automatic Acquisition
		8.2.1 Open-Loop Acquisition Mode
		8.2.2 Scanning Modes
		8.2.3 Performance of Acquisition
	8.3 Automatic Tracking
		8.3.1 Tracking System
		8.3.2 Compound-Axis Control System
		8.3.3 Accuracy of a Coarse Tracking Unit
		8.3.4 Fine Tracking Unit
	8.4 Fast Alignment Using Two-Dimensional Mirror
		8.4.1 Introduction
		8.4.2 Theoretical Model
		8.4.3 Experiments
	8.5 Alignment Error
		8.5.1 Attenuation Model of Optical Power
		8.5.2 Geometric Attenuation Model of Gaussian Beam with Alignment Error
		8.5.3 Average Geometric Attenuation Model with Alignment Error
	8.6 Summary and Prospects
	8.7 Questions
	8.8 Exercises
	References
9 Partially Coherent Optical Transmission
	9.1 Basic Parameters of a Light Beam
		9.1.1 Emission Beam
		9.1.2 Mutual Interference Function
		9.1.3 Beam Spreading, Drift, and Intensity Fluctuation
	9.2 Partially Coherent Light Model
		9.2.1 Description of Partially Coherent Light
		9.2.2 Partially Coherent Beam
	9.3 Beam Propagation in Atmospheric Turbulence
		9.3.1 Beam Spread and Beam Drift
		9.3.2 Drift and Spread of a Horizontally Propagating Beam
		9.3.3 Drift and Spread of a Slant Propagating Beam
		9.3.4 Fluctuation of Angle of Arrival
		9.3.5 Influence of Beam Drift and Spread on a Communication System
	9.4 Summary and Prospects
	9.5 Questions
	9.6 Exercises
	References
10 Optical Communication in the Future
	10.1 X-ray Space Optical Communication
		10.1.1 Backgrounds
		10.1.2 X-ray Communication System
		10.1.3 Development Directions and Prospects
	10.2 Orbital Angular Momentum Multiplexing Communication
		10.2.1 Vortex Beam
		10.2.2 Generation of a Vortex Beam
		10.2.3 OAM Multiplexing Communication System
	10.3 Neutrino Communication
		10.3.1 Neutrino
		10.3.2 Neutrino Communication
		10.3.3 Neutrino Communication System
		10.3.4 Key Technologies of Neutrino Communication
		10.3.5 Characteristics of Neutrino Communication
	10.4 Gravitational Wave Communication
		10.4.1 Detection of Gravitational Waves
		10.4.2 Generation of Gravitational Waves
		10.4.3 Difficulties in Gravitational Wave Detection
	10.5 Terahertz Wave Communication
		10.5.1 Terahertz Wave and Its Advantages
		10.5.2 Terahertz Wave Transmitting Antenna
		10.5.3 Terahertz Detector
		10.5.4 Terahertz Wave Modulator
		10.5.5 Transmission of Terahertz Waves in the Atmosphere
	10.6 Summary and Prospects
	10.7 Questions
	10.8 Exercises
	References