Channel Measurements and Models for 6G

In the early stage of 6G research,carrying out research on channel measurements and models is one of the fundamental and prerequisite works,as well as full of the challenges.Driven by the demand for multiple frequency bands,versatile scenarios,and various new technologies in the future,6G channels are expanding in multiple dimensions such as the space-time-frequency domains.Those all make 6G channel measurement and modeling research face a series of new challenges,e.g.,non-stationarity in multiple dimensions,the obvious increase in modeling complexity,and changes in theoretical premises and assumptions.It is therefore clear that more efforts are needed to understand propagation characteristics,especially in the new scenes and applications,and to develop a new paradigm for 6G channel modeling.

The main objective of this Feature Topic is to research the propagation characteristics in new scenarios and frequency bands,summarize the current status of the 6G channel modeling,and explore the new paradigm of channel modeling.These will enable the know-how for the simulation,evaluation,performance optimization,and network deployment of 6G systems.We present nine articles that have been accepted after a rigorous peer review process.

In the article entitled “Environment Information-Based Channel Prediction Method Assisted by Graph Neural Network” by Y.Sun et al.,the authors propose a new method for channel prediction by developing the GNNs with multi-target architecture and the graphs of the detected scatterers.The effective scatterers producing paths and the primary scatterers generating single propagation paths are detected by building the scatterer-centered communication environment graphs.

In the article entitled “Multi-Scenario Millimeter Wave Wireless Channel Measurements and Sparsity Analysis” by H.Mi et al.,the authors evaluate the sparsity of millimeter-wave channels based on millimeter-wave channel measurements.The key factors affecting millimeter-wave channel sparsity are explored and the impact of channel sparsity on channel eigenvalue and capacity is evaluated and analyzed.

In the article entitled “AG Channel Measurements and Characteristics Analysis in Hilly Scenarios for 6G UAV Communications” by C.Yu et al.,the authors provide a series of analyses of key channel characteristics for hilly environments.The authors compare typical channel characteristics under circular and straight trajectories and provide a reference for constructing future UAV communication systems in hilly scenarios.

In the article entitled “Long-Range VNA-Based Channel Sounder: Design and Measurement Validation at mmWave and sub-THz frequency bands” by B.Mikkel et al.,the authors present a state-of-art long-range 28 GHz and 300 GHz VNA-based channel sounder using optical cable solutions,which can support a measurement range up to 300 m and 600 m in principle,and the design,development,and validation of the long-range channel sounders at millimeter-wave and sub-THz bands are reported.

In the article entitled “A Novel Millimeter-wave Channel Measurement Platform for 6G Intelligent Railway Scenarios” by F.Dan et al.,the authors present a millimeter-wave channel measurement platform combined with improved multi-tone sounding signals for the 6G intelligent railway.The platform can enhance dynamic measurement capability in high-speed railway scenarios.Considering that V2V systems can integrate information and communication technology into transport infrastructure,cars,and other devices.

In the article entitled “A Geometry-Based Stochastic Scattering Channel Model for V2V Communications in Dense Urban Street Environments” by J.Zhou et al.,the authors propose a three-dimensional vehicle-to-vehicle channel model for dense urban communication environments.

In the article entitled “UWB Channel Modeling and Simulation With Continuous Frequency Response”by K.Mao et al.,the authors develop a closed-form simulation model for UWB channels and geometry-based parameter calculation method based on the analytical UWB channel model with continuous frequency response.

In the article entitled “A Fuzzy Clustering Algorithm Based on Multipath Component Trajectory for Millimeter Wave Radio Channels” by F.Du et al.,the authors propose a fuzzy clustering algorithm based on multipath component trajectory.Compared with the existing clustering algorithms,the proposed algorithm is able to identify the clusters in time-varying channels compared with the existing clustering algorithms.

In the article entitled “V2V Channel Modeling at 5.2 GHz for Highway Environment” by S.Jiang et al.,the authors show that Weibull fading parameter,transmit power,and vehicle density have a positive impact on connectivity probability,and PL exponent has a negative impact on connectivity probability.

We would like to thank all the authors for their excellent contributions and all the reviewers for their valuable comments.We also appreciate the strong and detailed support from Dr.Jianhua Lu,Editor-in-Chief of China Communications,and the IEEE Communications Society publishing team.