智能超表面(Reconfigurable Intelligent Surface,RIS)技术因其能够灵活操控信道环境的电磁特性,一经出现就引起了学术界和工业界的广泛关注.目前对于RIS辅助无线通信系统的理论研究与实际测试以静止场景为主,缺乏移动场景的研究.而由于RIS反射波束较窄,存在着移动场景下RIS反射波束难以对准目标,导致覆盖增强效果较差的问题.针对此问题,本文创新性地结合了波达方向(Direction Of Arrival,DOA)估计理论与RIS覆盖增强技术,实现了针对移动用户的RIS波束追踪与覆盖增强,并在此基础上搭建了Sub 6G频段下RIS辅助的移动场景原型平台.此外,本文在实验室对比了不同速度下,发射端移动而接收端保持静止、接收端移动而发射端保持静止两种场景下,经RIS反射后的接收信号功率与信干噪比(Signal Interference plus Noise Ratio,SINR)值.实测结果表明,在两种实测动态场景下RIS编码前后的接收信号功率与SINR均有提升,证明RIS在移动场景下仍然具有较好的性能提升.本文的研究结果可对后续移动场景下RIS辅助通信提供数据支撑与可参考原型平台.
RIS Beam Tracking and Coverage Enhancement Technology for Mobile Users
Reconfigurable intelligent surface(RIS)technology has attracted extensive attention from academia and in-dustry since its emergence owing to its ability to flexibly control the electromagnetic characteristics of the channel envi-ronment.Currently,the theoretical research and practical testing of RIS-assisted wireless communication systems are fo-cusing on stationary scenarios,and studies on mobile scenarios are lacking.However,because of the narrow RIS re-flected beam,the RIS reflected beam cannot easily aim at the target in mobile scenarios,resulting in a poor coverage en-hancement effect.To address this limitation,this study introduces an innovative solution that synergistically combines the principles of direction-of-arrival estimation and RIS coverage enhancement techniques.This novel approach facili-tates accurate RIS beam tracking for mobile users,ensuring consistent signal quality and coverage even in highly dy-namic environments.Based on this conceptual breakthrough,we developed a prototype platform tailored for RIS-assisted communication within the sub-6G frequency spectrum.This platform serves as a practical testament to theoreti-cal advancements,providing a tangible basis for further exploration and validation.To evaluate the performance of the proposed solution,we conducted a series of experiments within a controlled laboratory setting.These experiments were designed to assess the variations in received signal power and signal interference plus noise ratio(SINR)under two dis-tinct conditions:scenarios where the transmitter is in motion relative to a stationary receiver and vice versa,across vari-ous speeds.The measured results show that the received signal power and SINR are improved before and after RIS cod-ing in the two dynamic scenarios,proving that RIS still has scope for performance improvements in mobile communica-tion scenarios.Our research results can provide data support and a reference prototype platform for RIS-assisted commu-nication in future mobile communication scenarios.
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