  High-speed train (HST) communication is a very challenging scenario in
wireless communication systems due to its fast time-varying channels and
significant penetration loss. Thanks to the low cost and smart channel
reconfiguration ability, reconfigurable intelligent surface (RIS) has been
proposed as a promising technology to solve the aforementioned challenges
cost-effectively and to achieve high spectral and energy-efficiency in the
next-generation HST communication systems. In this article, we first provide a
novel RIS-aided HST wireless communication paradigm, including its main
challenges and application scenarios. Then, we propose practical solutions are
provided to realize efficient signal processing and resource management in the
considered system. Finally, future directions of RIS-aided HST communication
systems are pointed out to inspire further investigation in future work.
