Radio propagation environment plays a critical role in the performance of wireless communication systems, and understanding channel characteristics is vital for ensuring reliable communication links and optimizing system performance. Ray tracing is an effective method to investigate propagation characteristics in a complex environment, and how to quickly and accurately obtain environmental information needs to be solved. This paper presents dynamic environment reconstruction and ray tracing simulation in railway tunnel environment based on Simultaneous Localization and Mapping (SLAM) algorithm and Poisson reconstruction algorithm. Accurate channel parameters are obtained and analyzed based on ray tracing simulation. Both straight and curved tunnels are considered and investigated, and the results show the channel characteristics in complex railway tunnel environments.

Reconfigurable intelligent surfaces (RISs) have attracted significant attention due to their capability in customizing wireless communication environments to improve system performance. In this study, we investigate the performance of an RIS-assisted multi-user multiple-input single-output wireless communication system, considering the impact of channel aging caused by users’ relative movements. In particular, first, we propose a model incorporating the joint effects of channel aging and channel estimation errors to investigate the performance of the RIS-assisted system. Then, we derive novel closed-form expressions for characterizing the sum spectral efficiency with zero-forcing precoding. From our analysis, we unveil that an increase in the temporal channel correlation coefficient, the number of base station antennas, and the received power at the users could help improve system performance. Furthermore, increasing the number of reflecting elements M of the RIS generally yields a good system performance, but with a diminishing return when M is sufficiently large. Finally, simulation results are presented to validate the accuracy of the analytical results.

As a new generation of application infrastructure and strategic emerging technologies, the internet of things (IoT) is an inevitable trend to be integrated into the rapid development of high-speed railways (HSR). This article first introduces the concept and key technologies of the HSR IoT, and then analyzes the HSR’s requirements for the IoTs. Based on these concepts, a system architecture of the HSR IoT is proposed to expand the in-depth applications of IoT in various fields of the HSR industry. Finally, future development trends of the HSR IoT are discussed. This article is expected to provide some useful insights into the study and evolution of HSR IoT.