Reconfigurable Intelligent Surface Assisted Railway Communications: A survey

TL;DR

This survey reviews the application of reconfigurable intelligent surfaces (RIS) to enhance millimeter wave railway communications, addressing coverage issues caused by high penetration loss and exploring optimization techniques and future research directions.

Contribution

It provides a comprehensive overview of RIS types, optimization algorithms, and recent railway communication studies, highlighting future research avenues.

Findings

RIS improves mmWave railway coverage and reliability.

Various RIS optimization algorithms are effective in phase shift tuning.

Future research directions include advanced RIS designs and integration strategies.

Abstract

The number of train passengers and the demand for high data rates to handle new technologies such as video streaming and IoT technologies are continuously increasing. Therefore the exploration of millimeter waves (mmWave) band is a key technology to meet this demand. However, the high penetration loss makes mmWave very sensitive to blocking, limiting its coverage area. One promising, efficient, and low-cost solution is the reconfigurable intelligent surface (RIS). This paper reviews the state of the art of RIS for railway communications in the mmWave context. First, we present the different types of RIS and review some optimization algorithms used in the literature to find the RIS phase shift. Then, we review recent works on RIS in the railway domain and provide future directions.