Preface About the Authors Chapter 1: Fundamentals of Metasurfaces for Wireless Communications Introduction of Metamaterial and Metasurface Evolutions of Reconfigurable Intelligent Surface (RIS)-Related Wireless Technologies Multi-Antenna Technology Coordinated Multi-Point Processing (CoMP) Micro/Pico/femto Cells Relay System Performance Requirements for 6G Application Scenarios Key Performance Indicators Basics about Performance Evaluation Methodologies Chapter 2: Modeling of a RIS for Wireless Communications Overview of Channel Models for Mobile Communications Large-Scale Fading Models Small-Scale Fading Models Spatial Channel Models Simplified Model for Spatial Channels Antenna Models and Configurations Large-Scale Channel Models for a RIS Free-Space Pathloss Models for a RIS More Realistic Large-Scale Fading Models for RIS Small-Scale Channel Models for RIS Electromagnetic Field Modeling of Metasurface Structures Chapter 3: Designs of Metasurface Devices Basic Design Principles of Metasurface Devices Typical Metamaterials and Devices Basic Structures of Metamaterial Devices Design Principles of Metasurface Active RIS Elements Simulations and Measurements of Metasurface Devices Electromagnetic Simulations Performance Testing of Actual Devices Control of Metasurface Devices Non-Ideal Characteristics Control Mechanisms of Tunable Metasurface Codebook Designs of the RIS Uniqueness of Codebook Design for the RIS Examples of the RIS Codebook Designs Near-Field Communications Near-Field Basics Polar Coordinates for the Near-Field Beam Squinting in Wideband Operation and Solutions Metasurface-Based Beamforming at the Base Station Chapter 4: System Implementations of a RIS for Wireless Communications Basic System Models and Performances for Metasurface-Based Relay System Models Theoretical Performance Analysis Simplified Model and Performance Analysis Beamforming Techniques for a RIS Beam-Based Techniques Random-Sampling-Based Technique RIS Channel Estimation and Feedback for Small-Scale Fading Direction Finding Via Time-Space Coding Link-Level Simulations Simulation Parameters and Methodology Preliminary Link-Level Simulation Results System-Level Simulations System Configurations and Simulation Preliminary Simulation Results Chapter 5: Standardization and Trials of RIS-Aided Wireless Communications Overview and Key Features of Relay Technology in Standardization Potential Deployment Scenarios Basic Categories of an LTE Relay Type 1 Relay Type 2 Relay Brief Discussion on an LTE Full-Dimensional MIMO Field Trials RIS Trial in Nanjing RIS Trial in Shenzhen Standardization Road Map for the RIS Lessons Learned from the LTE Era Different Modes of Operation for the RIS 3GPP Release 18 Network-Controlled Repeater Comparison Between Network-Controlled Repeater and RIS Future Road Map for RIS Standardization Index.