Backscatter communication, an emerging technology in passive Internet of Things (IoT), enables data transmission by modulating reflected ambient or dedicated radio frequency signals. It offers core advantages including ultra-low power consumption, low cost, easy deployment, and maintenance. In recent years, standards organizations such as 3GPP and CCSA have prioritized passive IoT development, with particular emphasis on advancing passive sensing and localization capabilities. Against this technical backdrop, backscatter technology has emerged as a critical solution for low-power positioning, leveraging its ultra-low power attributes in operational environments. This paper focuses specifically on backscatter positioning technology. We elucidate its low-power communication principles, trace its technical evolution, and provide a comprehensive review of prevalent localization algorithms alongside their latest research advances. Based on this foundation, the paper explores the critical technical challenges faced by this technology. Furthermore, significant application potential of backscatter localization within the aviation sector is highlighted, focusing on key scenarios such as Unmanned Aerial Vehicle (UAV)-based material delivery and disaster search-and-rescue operations, as well as airline baggage tracking and ground vehicle positioning at civil aviation airports.

The rapid expansion of railways, especially High-Speed Railways (HSRs), has drawn considerable interest from both academic and industrial sectors. To meet the future vision of smart rail communications, the rail transport industry must innovate in key technologies to ensure high-quality transmissions for passengers and railway operations. These systems must function effectively under high mobility conditions while prioritizing safety, ecofriendliness, comfort, transparency, predictability, and reliability. On the other hand, the proposal of 6 G wireless technology introduces new possibilities for innovation in communication technologies, which may truly realize the current vision of HSR. Therefore, this article gives a review of the current advanced 6 G wireless communication technologies for HSR, including random access and switching, channel estimation and beamforming, integrated sensing and communication, and edge computing. The main application scenarios of these technologies are reviewed, as well as their current research status and challenges, followed by an outlook on future development directions.

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.