RIS-Assisted Communications in Correlated Rayleigh Channels:Comparison of Training Overhead Reduction Schemes

作     者：Jue Wang Shuaifeng Lu Jing Wang Zhenyu Jiang Rui Tang Ruifeng Gao Yingdong Hu Ye Li Jue Wang;Shuaifeng Lu;Jing Wang;Zhenyu Jiang;Rui Tang;Ruifeng Gao;Yingdong Hu;Ye Li

作者机构：School of Information Science and TechnologyNantong UniversityNantong 226109China Department of Electronic EngineeringTsinghua UniversityBeijing 100084China School of Transportation and Civil EngineeringNantong UniversityNantong 226109China Nantong Research Institute for Advanced Communication TechnologiesNantong 226109China 

出 版 物：《China Communications》 (中国通信（英文版）)

年 卷 期：2022年第19卷第12期

页      面：41-53页

核心收录：

学科分类：0810[工学-信息与通信工程] 08[工学] 0804[工学-仪器科学与技术] 080402[工学-测试计量技术及仪器] 

基　　金：the National Natural Science Foundation of China under Grants 62171240,61771264,62001254,61971467,the Key Research and Development Program of Jiangsu Province of China under Grant BE2021013-1 the Science and Technology Program of Nantong under Grants JC2021121,JC2021017. 

主　　题：reconfigurable intelligent surface correlated Rayleigh channel training overhead ergodic achievable rate 

摘      要：Channel training in reconfigurable intelligent surface(RIS)-assisted communications is usually conducted in an on-off manner,resulting in unaffordable training time overhead when the number of RIS elements is large.In this paper,for correlated Rayleigh channels,we compare three typical training overhead reduction schemes,namely RIS element selection(Scheme 1),element grouping(Scheme 2),and statistical CSI-based phase shifts design(Scheme3).For Scheme 1 and Scheme 2,we propose two algorithms to select RIS elements(or form element groups) and determine the optimal number of activated elements(or formed groups),based on the channel correlation information only;for Scheme 3,we consider a semi-definite programming-based approach in the literature,and propose an alternative dominant eigenvector-based method for determining the RIS phase shifts vector.Via extensive simulations,we compare the achievable ergodic rates of these schemes versus the signal-to-noise ratio,the channel correlation level,and the element number-to-coherent time ratio,respectively,and discuss possible switching of the three schemes over these system parameters.At last,operation regions of the considered training overhead reduction schemes are shown in the plane characterized by the system parameters,which provides useful guidelines for practical scheme determination.