Advanced 6 G wireless communication technologies for intelligent high-speed railways

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, eco-friendliness, 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.