6G Key Technologies: A Comprehensive Guide

Description

6G Key Technologies An accessible and integrated roadmap to the technologies enabling 6G development In 6G Key Technologies: A Comprehensive Guide, two internationally well-recognized experts deliver a thoroughly original and comprehensive exploration of the technologies enabling and contributing to the development of 6G. The book presents the vision of 6G by reviewing the evolution of communications technologies toward 6G and examining the factors driving that development, as well as their requirements, use cases, key performance indicators, and more. Readers will discover: Thorough introductions to the standardization and technology evolution toward 6G, as well as the vision behind the development of 6G in terms of architectures, algorithms, protocols, and applications. In-depth explorations of full-spectrum wireless technologies in 6G, including enhanced millimeter wave technologies, terahertz-based communications and networking, visible-light and optical wireless communications. Fulsome discussions of smart radio networks and new air interface technologies for 6G including intelligent reflecting surface, cellular massive MIMO, cell-free massive MIMO, adaptive and non-orthogonal multiple access technologies. Perfect for professional engineers, researchers, manufacturers, network operators, and software developers, 6G Key Technologies: A Comprehensive Guide will also earn a place in the libraries of graduate students studying in wireless communications, artificial intelligence, signal processing, microwave technology, information theory, antenna and propagation, system-on-chip implementation, and computer networks. Cover Title Page Copyright Contents Preface List of Abbreviations Part I The Vision of 6G and Technical Evolution Chapter 1 Standards History of Cellular Systems Toward 6G 1.1 0G: Pre‐Cellular Systems 1.2 1G: The Birth of Cellular Network 1.2.1 Nordic Mobile Telephone (NMT) 1.2.2 Advanced Mobile Phone System (AMPS) 1.3 2G: From Analog to Digital 1.3.1 Global System for Mobile Communications (GSM) 1.3.2 Digital Advanced Mobile Phone System (D‐AMPS) 1.3.3 Interim Standard 95 (IS‐95) 1.3.4 Personal Digital Cellular (PDC) 1.3.5 General Packet Radio Service (GPRS) 1.3.6 Enhanced Data Rates for GSM Evolution (EDGE) 1.4 3G: From Voice to Data‐Centric 1.4.1 Wideband Code‐Division Multiple Access (WCDMA) 1.4.2 Code‐Division Multiple Access 2000 (CDMA2000) 1.4.3 Time Division‐Synchronous Code‐Division Multiple Access (TD‐SCDMA) 1.4.4 Worldwide Interoperability for Microwave Access (WiMAX) 1.5 4G: Mobile Internet 1.5.1 Long‐Term Evolution‐Advanced (LTE‐Advanced) 1.5.2 WirelessMAN‐Advanced 1.6 5G: From Human to Machine 1.7 Beyond 5G 1.8 Conclusions References Chapter 2 Pre‐6G Technology and System Evolution 2.1 1G – AMPS 2.1.1 System Architecture 2.1.2 Key Technologies 2.1.2.1 Frequency Reuse 2.1.2.2 Cell Splitting 2.1.2.3 Sectorization 2.1.2.4 Handover 2.1.2.5 Frequency‐Division Multiple Access 2.2 2G – GSM 2.2.1 System Architecture 2.2.1.1 Mobile Station Subsystem 2.2.1.2 Bases Station Subsystem 2.2.1.3 Network and Switching Subsystem 2.2.1.4 Operation and Support Subsystem 2.2.1.5 General Packet Radio Service 2.2.1.6 Gateway GPRS Support Node 2.2.2 Key Technologies 2.2.2.1 Time‐Division Multiple Access 2.2.2.2 Frequency Hopping 2.2.2.3 Speech Compression 2.2.2.4 Channel Coding 2.2.2.5 Digital Modulation 2.2.2.6 Discontinuous Transmission (DXT) 2.3 3G – WCDMA 2.3.1 System Architecture 2.3.1.1 User Equipment 2.3.1.2 UMTS Terrestrial Radio Access Network 2.3.1.3 Core Network 2.3.2 Key Technologies 2.3.2.1 Code‐Division Multiple Access 2.3.2.2 Rake Receiver 2.3.2.3 Turbo Codes 2.4 4G – LTE 2.4.1 System Architecture 2.4.1.1 Evolved Universal Terrestrial Radio Access Network 2.4.1.2 Evolved Packet Core 2.4.2 Key Technologies 2.4.2.1 Orthogonal Frequency‐Division Multiplexing 2.4.2.2 Carrier Aggregation 2.4.2.3 Relaying 2.4.2.4 Heterogeneous Network 2.4.2.5 Coordinated Multi‐Point Transmission and Reception 2.4.2.6 Device‐to‐Device Communications 2.4.2.7 License‐Assisted Access 2.5 5G – New Radio 2.5.1 System Architecture 2.5.1.1 5G Core Network 2.5.1.2 Next Generation Radio Access Network 2.5.2 Key Technologies 2.5.2.1 Massive MIMO 2.5.2.2 Millimeter Wave 2.5.2.3 Non‐Orthogonal Multiple Access 2.5.2.4 SDN/NFV 2.5.2.5 Network Slicing 2.5.2.6 Polar Codes 2.6 Conclusions References Chapter 3 The Vision of 6G: Drivers, Enablers, Uses, and Roadmap 3.1 Background 3.2 Explosive Mobile Traffic 3.3 Use Cases 3.4 Usage Scenarios 3.5 Performance Requirements 3.6 Research Initiatives and Roadmap 3.6.1 ITU 3.6.2 Third Generation Partnership Project 3.6.3 Industry 3.6.4 Europe 3.6.5 The United States 3.6.6 China 3.6.7 Japan 3.6.8 South Korea 3.7 Key Technologies 3.7.1 Millimeter Wave 3.7.2 Terahertz Communications 3.7.3 Optical Wireless Communications 3.7.4 Massive MIMO 3.7.5 Intelligent Reflecting Surfaces 3.7.6 Next‐Generation Multiple Access 3.7.7 Open Radio Access Network 3.7.8 Non‐Terrestrial Networks 3.7.9 Artificial Intelligence 3.7.10 Communication‐Computing‐Sensing Convergence 3.8 Conclusions References Part II Full‐Spectra Wireless Communications in 6G Chapter 4 Enhanced Millimeter‐Wave Wireless Communications in 6G 4.1 Spectrum Shortage 4.2 mmWave Propagation Characteristics 4.2.1 Large‐Scale Propagation Effects 4.2.1.1 Free‐Space Propagation Loss 4.2.1.2 NLOS Propagation and Shadowing 4.2.1.3 Atmospheric Attenuation 4.2.2 Small‐Scale Propagation Effects 4.2.3 Delay Spread and Coherence Bandwidth 4.2.4 Doppler Spread and Coherence Time 4.2.5 Angular Spread 4.3 Millimeter‐Wave Channel Models 4.3.1 Large‐Scale Fading 4.3.2 3GPP Channel Models 4.3.2.1 Urban Micro Scenario 4.3.2.2 Urban Macro Scenario 4.3.2.3 Indoor Scenario 4.3.3 Small‐Scale Fading 4.4 mmWave Transmission Technologies 4.4.1 Beamforming 4.4.1.1 Digital Beamforming 4.4.1.2 Analog Beamforming 4.4.1.3 Hybrid Beamforming 4.4.1.4 3D Beamforming 4.4.2 Initial Access 4.4.2.1 Multi‐Beam Synchronization and Broadcasting 4.4.2.2 Conventional Initial Access in LTE 4.4.2.3 Beam‐Sweeping Initial Access in NR 4.4.3 Omnidirectional Beamforming 4.4.3.1 Random Beamforming 4.4.3.2 Enhanced Random Beamforming 4.4.3.3 Complementary Random Beamforming 4.5 Summary References Chapter 5 Terahertz Technologies and Systems for 6G 5.1 Potential of Terahertz Band 5.1.1 Spectrum Limit 5.1.2 The Need of Exploiting Terahertz Band 5.1.3 Spectrum Regulation on Terahertz Band 5.2 Terahertz Applications 5.2.1 Terahertz Wireless Communications 5.2.1.1 Terabit Cellular Hotspot 5.2.1.2 Terabit Wireless Local‐Area Network 5.2.1.3 Terabit Device‐To‐Device Link 5.2.1.4 Secure Wireless Communication 5.2.1.5 Terabit Wireless Backhaul 5.2.1.6 Terahertz Nano‐Communications 5.2.2 Non‐Communication Terahertz Applications 5.2.2.1 Terahertz Sensing 5.2.2.2 Terahertz Imaging 5.2.2.3 Terahertz Positioning 5.3 Challenges of Terahertz Communications 5.3.1 High Free‐Space Path Loss 5.3.2 Atmospheric Attenuation 5.3.3 Weather Effects 5.3.4 Blockage 5.3.5 High Channel Fluctuation 5.4 Array‐of‐Subarrays Beamforming 5.5 Lens Antenna 5.5.1 Refraction of Radio Waves 5.5.2 Lens Antenna Array 5.6 Case Study – IEEE 802.15.3d 5.6.1 IEEE 802.15.3d Usage Scenarios 5.6.2 Physical Layer 5.6.2.1 Channelization 5.6.2.2 Modulation 5.6.2.3 Forward Error Correction 5.6.3 Medium Access Control 5.6.4 Frame Structure 5.6.4.1 Preamble 5.6.4.2 PHY Header 5.6.4.3 MAC Header 5.6.4.4 Construction Process of Frame Header 5.7 Summary References Chapter 6 Optical and Visible Light Wireless Communications in 6G 6.1 The Optical Spectrum 6.1.1 Infrared 6.1.2 Visible Light 6.1.3 Ultraviolet 6.2 Advantages and Challenges 6.3 OWC Applications 6.4 Evolution of Optical Wireless Communications 6.4.1 Wireless Infrared Communications 6.4.2 Visible Light Communications 6.4.3 Wireless Ultraviolet Communications 6.4.4 Free‐Space Optical Communications 6.5 Optical Transceiver 6.6 Optical Sources and Detectors 6.6.1 Light‐Emitting Diode 6.6.2 Laser Diode 6.6.3 Photodiode 6.7 Optical Link Configuration 6.8 Optical MIMO 6.8.1 Spatial Multiplexing 6.8.2 Spatial Modulation 6.9 Summary References Part III Smart Radio Networks and Air Interface Technologies for 6G Chapter 7 Intelligent Reflecting Surface‐Aided Communications for 6G 7.1 Basic Concept 7.2 IRS‐Aided Single‐Antenna Transmission 7.2.1 Signal Model 7.2.2 Passive Beamforming 7.2.3 Product‐Distance Path Loss 7.3 IRS‐Aided Multi‐Antenna Transmission 7.3.1 Joint Active and Passive Beamforming 7.3.1.1 SDR Solution 7.3.1.2 Alternating Optimization 7.3.2 Joint Precoding and Reflecting 7.4 Dual‐Beam Intelligent Reflecting Surface 7.4.1 Dual Beams Over Hybrid Beamforming 7.4.2 Dual‐Beam IRS 7.4.3 Optimization Design 7.5 IRS‐Aided Wideband Communications 7.5.1 Cascaded Frequency‐Selective Channel 7.5.2 IRS‐Aided OFDM System 7.5.3 Rate Maximization 7.6 Multi‐User IRS Communications 7.6.1 Multiple Access Model 7.6.2 Orthogonal Multiple Access 7.6.2.1 Time‐Division Multiple Access 7.6.2.2 Frequency‐Division Multiple Access 7.6.3 Non‐Orthogonal Multiple Access 7.7 Channel Aging and Prediction 7.7.1 Outdated Channel State Information 7.7.1.1 Doppler Shift 7.7.1.2 Phase Noise 7.7.2 Impact of Channel Aging on IRS 7.7.3 Classical Channel Prediction 7.7.3.1 Autoregressive Model 7.7.3.2 Parametric Model 7.7.4 Recurrent Neural Network 7.7.5 RNN‐Based Channel Prediction 7.7.5.1 Flat‐Fading Channel Prediction 7.7.5.2 Frequency‐Selective Fading Channel Prediction 7.7.6 Long‐Short Term Memory 7.7.7 Deep Learning‐Based Channel Prediction 7.8 Summary References Chapter 8 Multiple Dimensional and Antenna Techniques for 6G 8.1 Spatial Diversity 8.2 Receive Combining 8.2.1 Selection Combining 8.2.2 Maximal Ratio Combining 8.2.3 Equal‐Gain Combining 8.3 Space‐Time Coding 8.3.1 Repetition Coding 8.3.2 Space‐Time Trellis Codes 8.3.3 Alamouti Coding 8.3.4 Space‐Time Block Codes 8.4 Transmit Antenna Selection 8.5 Beamforming 8.5.1 Classical Beamforming 8.5.2 Single‐Stream Precoding 8.6 Spatial Multiplexing 8.6.1 Single‐User MIMO 8.6.2 MIMO Precoding 8.6.2.1 Full CSI at the Transmitter 8.6.2.2 Limited CSI at the Transmitter 8.6.3 MIMO Detection 8.6.3.1 Maximum‐Likelihood Detection 8.6.3.2 Linear Detection 8.6.3.3 Successive Interference Cancelation 8.7 Summary References Chapter 9 Cellular and Cell‐Free Massive MIMO Techniques in 6G 9.1 Multi‐User MIMO 9.1.1 Broadcast and Multiple‐Access Channels 9.1.2 Multi‐User Sum Capacity 9.1.3 Dirty Paper Coding 9.1.4 Zero‐Forcing Precoding 9.1.5 Block Diagonalization 9.2 Massive MIMO 9.2.1 CSI Acquisition 9.2.2 Linear Detection in Uplink 9.2.2.1 Matched Filtering 9.2.2.2 ZF Detection 9.2.2.3 MMSE Detection 9.2.3 Linear Precoding in Downlink 9.2.3.1 Conjugate Beamforming 9.2.3.2 ZF Precoding 9.2.3.3 Regularized ZF Precoding 9.3 Multi‐Cell Massive MIMO 9.3.1 Pilot Contamination 9.3.2 Uplink Data Transmission 9.3.3 Downlink Data Transmission 9.4 Cell‐Free Massive MIMO 9.4.1 Cell‐Free Network Layout 9.4.2 Uplink Training 9.4.3 Uplink Signal Detection 9.4.3.1 Matched Filtering 9.4.3.2 ZF Detection 9.4.3.3 MMSE Detection 9.4.4 Conjugate Beamforming 9.4.5 Zero‐Forcing Precoding 9.4.6 Impact of Channel Aging 9.4.6.1 Channel Aging 9.4.6.2 Performance Degradation 9.5 Opportunistic Cell‐Free Communications 9.5.1 Cell‐free Massive Wideband Systems 9.5.2 Opportunistic AP Selection 9.5.3 Spectral Efficiency Analysis 9.6 Summary References Chapter 10 Adaptive and Non‐Orthogonal Multiple Access Systems in 6G 10.1 Frequency‐Selective Fading Channel 10.2 Multi‐Carrier Modulation 10.2.1 The Synthesis and Analysis Filters 10.2.2 Polyphase Implementation 10.2.3 Filter Bank Multi‐Carrier 10.3 Orthogonal Frequency‐Division Multiplexing 10.3.1 DFT Implementation 10.3.2 Cyclic Prefix 10.3.3 Frequency‐Domain Signal Processing 10.3.4 Out‐of‐Band Emission 10.4 Orthogonal Frequency‐Division Multiple Access 10.4.1 Orthogonal Frequency‐Division Multiple Access 10.4.2 Single‐Carrier Frequency‐Division Multiple Access 10.4.3 Cyclic Delay Diversity 10.4.4 Multi‐Cell OFDMA 10.5 Cell‐Free Massive MIMO‐OFDMA 10.5.1 The System Model 10.5.2 The Communication Process 10.5.2.1 Uplink Training 10.5.2.2 Uplink Payload Data Transmission 10.5.2.3 Downlink Payload Data Transmission 10.5.3 User‐Specific Resource Allocation 10.6 Non‐Orthogonal Multiple Access 10.6.1 Fundamentals of NOMA 10.6.1.1 Downlink Non‐Orthogonal Multiplexing 10.6.1.2 Uplink Non‐Orthogonal Multiple Access 10.6.2 Multi‐User Superposition Coding 10.6.3 Uplink Grant‐Free Transmission 10.6.4 Code‐Domain NOMA 10.6.4.1 Low‐Density Signature‐CDMA/OFDM 10.6.4.2 Sparse Code Multiple Access 10.7 Summary References Index EULA