Reconfigurable intelligent surface (RIS)-aided near-field communications is investigated. First, the necessity of investigating RIS-aided near-field communications and the advantages brought about by the unique spherical-wave-based near-field propagation are discussed. Then, the family of patch-array-based RISs and metasurface-based RISs are introduced along with their respective near-field channel models. A pair of fundamental performance limits of RIS-aided near-field communications, namely their power scaling law and effective degrees-of-freedom, are analyzed for both patch-array-based and metasurface-based RISs, which reveals the potential performance gains that can be achieved. Furthermore, the associated near-field beam training and beamforming design issues are studied, where a two-stage hierarchical beam training approach and a low-complexity element-wise beamforming design are proposed for RIS-aided near-field communications. Finally, a suite of open research problems is highlighted for motivating future research.
@article{arxiv.2312.13004,
title = {Reconfigurable Intelligent Surface-Aided Near-field Communications for 6G: Opportunities and Challenges},
author = {Xidong Mu and Jiaqi Xu and Yuanwei Liu and Lajos Hanzo},
journal= {arXiv preprint arXiv:2312.13004},
year = {2024}
}
Comments
7 pages, 7 figures, this paper was accepted for publication in IEEE Vehicular Technology Magazine