Hybrid near- and far-field three-stage beam training with beam split for RIS-assisted OFDM communications  

作　　者：Zhichao CHENG Shupei ZHANG Shu FU Boya DI 

机构地区：[1]School of Electronics Engineering and Computer Science,Peking University,Beijing 100871,China [2]State Key Laboratory of Advanced Optical Communication Systems and Networks,School of Electronics,Peking University,Beijing 100871,China [3]Department of Microelectronics and Communication Engineering,Chongqing University,Chongqing 400044,China

出　　处：《Frontiers of Information Technology & Electronic Engineering》2024年第12期1664-1678,共15页信息与电子工程前沿(英文版)

基　　金：Project supported by the Natural Science Foundation of Beijing Municipality,China(Nos.QY23039,4222005,and L212027);the National Natural Science Foundation of China(Nos.62322101,62227809,and 62271012)。

摘　　要：With the development of millimeter-wave(mmWave)communication systems,large-scale reconfigurable intelligent surfaces(RISs)have gained considerable attention as a promising technology for signal strength enhancement and coverage extension.However,as the antenna scale and bandwidth increase,RIS-assisted wideband orthogonal frequency division multiplexing(OFDM)communication systems face challenges due to the near-field range expansion and the beam split effect over the high-frequency band,complicating the acquisition of channel state information(CSI).To tackle these challenges,we present a codebook-based three-stage beam training scheme by using the beam split effect to bypass CSI estimation.Specifically,by analyzing the beam split effect in RIS-assisted OFDM communication systems,we propose a beam-split-aware codebook capable of covering both the near and far fields with fewer codewords compared to conventional narrow-band codebooks.Using such a codebook,a three-stage beam training mechanism is adopted to obtain the optimal codeword with low time overhead,thereby facilitating subsequent beamforming.Simulation results demonstrate that the proposed scheme outperforms existing near-and far-field codebook-based schemes in terms of the beam training resolution and sum rate in the hybrid near–far field.

关 键 词：Near-far field Beam split Codebook design Beam training Reconfigurable intelligent surfaces 

分 类 号：TN92[电子电信—通信与信息系统]