智能超表面辅助的5G高铁场景信道特性

Reconfigurable intelligent surface-assisted channel characteristics in 5G high-speed railway scenario

为推进智能铁路总体建设,助力铁路数字化转型,基于5G的铁路专用移动通信系统(5G for Railway,5G-R)成为铁路智能联接的首选.作为最具发展潜力的B5G关键技术之一,智能超表面(Reconfigurable Intelligent Surface,RIS)具有复杂度低、成本低和易于部署等优点,为5G智能高铁(High-Speed Railway,HSR)通信的发展提供了新契机.采用射线跟踪技术,精准刻画了2.1GHz频段下高铁高架桥场景的电波传播特性.基于准确的电波传播特性,利用发射机、反射面和接收机三者之间的角度关系,对RIS的部署位置和波束指向进行了设计.在获得RIS辅助下的信道传递函数后,对部署RIS前后的多维度信道特性进行了比较和研究.结果表明:引入RIS能够提升信号覆盖质量,加剧多径信号在时间域和空间域的色散程度,降低2T2R信道间的相关性,从而提高信道容量.本文研究成果可为高铁通信场景下5G-R系统与RIS的联合设计、优化提供理论指导和数据支撑.

To promote the overall construction of the intelligent railways and facilitate the digital transformation of railways,the 5G for railway(5G-R) system will become the first choice for railways intelligent connections.Reconfigurable Intelligent Surface(RIS) is one of the most promising technologies for beyond 5G.RIS has the characteristics of low cost,low complexity,and easy deployment,which provides a new opportunity to develop intelligent High-Speed Railway(HSR) communications.In this paper,the ray tracing technology is exploited to accurately model the radio propagation characteristics at the 2.1 GHz frequency band of the HSR viaduct scenario.Based on the accurate radio propagation characteristics,the angle relationship among the transmitter,reflecor and receiver,the deployment position and beam pointing of RIS are designed.After obtaining the channel transfer function with the assistance of RIS,the multi-dimensional channel characteristics are compared and studied in the case of without RIS and with RIS.The outcomes indicate that the deployment of RIS can improve the wireless signal coverage quality;intensify the dispersion of multipath signals in the time and space domains;and reduce the correlation between the 2T2R channels,thereby increasing the channel capacity.The research in this paper provides theoretical guidance and data support for the joint design and optimization of 5G-R system and RIS in HSR communication scenarios.