COST INTERACT working group (WG)1 aims at increasing the theoretical and experimental understanding of radio propagation and channels in environments of interest and at deriving models for design, simulation, planning and operation of future wireless systems. Wide frequency ranges from sub-GHz to terahertz (THz), potentially high mobility, diverse and highly cluttered environments, dense networks, massive antenna systems, and the use of intelligent surfaces, are some of the challenges for radio channel measurements and modeling for next generation systems. As indicated in [1], with increased number of use cases (e.g., those identified by one6G [2] and shown in Fig. 1) to be supported and a larger number of frequency bands, a paradigm shift in channel measurements and modeling will be required. To address the particular challenges that come with such a paradigm shift, WG1 started the work on relevant topics, ranging from channel sounder design, metrology and measurement methodologies, measurements, modeling, and systematic dataset collection and analysis. In addition to the core activities of WG1, based on the strong interest of the participants, two sub-working groups (subWGs) have been initiated as part of WG1: i) subWG1.1 on millimeter-wave (mmWave) and THz sounding (subWG THz) and ii) subWG1.2 on propagation aspects related to reconfigurable intelligent surfaces (RIS) (subWG RIS). This white paper has two main goals: i) it summarizes the state-of-theart in radio channel measurement and modeling and the key challenges that the scientific community will have to face over the next years to support the development of 6G networks, as identified by WG1 and its subWGs; and ii) it charts the main directions for the work of WG1 and subWGs for the remainder of COST INTERACT duration (i.e., until October 2025).

翻译：COST INTERACT工作组（WG1）旨在提升对感兴趣环境中无线电传播与信道的理论与实验认知，并推导出用于未来无线系统设计、仿真、规划与运行的模型。从亚千兆赫兹到太赫兹的宽频范围、潜在的高移动性、多样化且高度杂乱的传播环境、密集网络、大规模天线系统以及智能反射面的应用，是下一代系统无线信道测量与建模面临的部分挑战。如文献[1]所述，随着需支持的使用场景数量增多（例如one6G[2]所识别并在图1中展示的场景）以及频段数量增加，信道测量与建模将需要范式转变。为应对这一范式转变带来的特定挑战，WG1已启动相关课题研究，涵盖信道探测仪设计、计量学与测量方法、测量、建模以及系统性数据集收集与分析。除WG1核心活动外，基于参与者的浓厚兴趣，WG1内部已设立两个子工作组：i) 子工作组1.1——毫米波与太赫兹信道探测；ii) 子工作组1.2——可重构智能反射面相关传播特性。本白皮书包含两大目标：i) 总结WG1及其子工作组所识别的无线信道测量与建模领域现有技术水平，以及科学界在未来几年支持6G网络发展所需面临的关键挑战；ii) 规划WG1及其子工作组在COST INTERACT项目剩余周期内（即至2025年10月）的主要工作方向。