Degrees of Freedom of Holographic MIMO in Multi-User Near-Field Channels

IF 4.4 3区计算机科学 Q2 TELECOMMUNICATIONS

IEEE Communications Letters Pub Date : 2025-03-28 DOI:10.1109/LCOMM.2025.3555796

Houfeng Chen;Shaohua Yue;Marco Di Renzo;Hongliang Zhang

{"title":"Degrees of Freedom of Holographic MIMO in Multi-User Near-Field Channels","authors":"Houfeng Chen;Shaohua Yue;Marco Di Renzo;Hongliang Zhang","doi":"10.1109/LCOMM.2025.3555796","DOIUrl":null,"url":null,"abstract":"Holographic multiple-input multiple-output (HMIMO) is an emerging technology for 6G communications, in which numerous antenna units are integrated in a limited space. As the HMIMO array aperture expands, the near-field region of the array is dramatically enlarged, resulting in more users being located in the near-field region. This creates new opportunities for wireless communications. In this context, the evaluation of the spatial degrees of freedom (DoF) of HMIMO multi-user systems in near-field channels is an open problem, as the analytical methods utilized for evaluating the DoF in far-field channels cannot be directly applied. In this letter, we propose a novel method to calculate the DoF of HMIMO in multi-user near-field channels. We first derive the DoF for a single user in the near field, and then extend the analysis to multi-user scenarios. In this latter scenario, we focus on the impact of spatial blocking between HMIMO users. The derived analytical framework reveals that the DoF of HMIMO in multi-user near-field channels is not in general given by the sum of the DoF of the HMIMO single-user setting because of spatial blocking. Simulation results demonstrate the effectiveness of the proposed method. In the considered case study, the number of DoF reduces by 21.2% on average due to spatial blocking.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 6","pages":"1186-1190"},"PeriodicalIF":4.4000,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"IEEE Communications Letters","FirstCategoryId":"94","ListUrlMain":"https://ieeexplore.ieee.org/document/10945401/","RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"TELECOMMUNICATIONS","Score":null,"Total":0}

引用次数: 0

Abstract

Holographic multiple-input multiple-output (HMIMO) is an emerging technology for 6G communications, in which numerous antenna units are integrated in a limited space. As the HMIMO array aperture expands, the near-field region of the array is dramatically enlarged, resulting in more users being located in the near-field region. This creates new opportunities for wireless communications. In this context, the evaluation of the spatial degrees of freedom (DoF) of HMIMO multi-user systems in near-field channels is an open problem, as the analytical methods utilized for evaluating the DoF in far-field channels cannot be directly applied. In this letter, we propose a novel method to calculate the DoF of HMIMO in multi-user near-field channels. We first derive the DoF for a single user in the near field, and then extend the analysis to multi-user scenarios. In this latter scenario, we focus on the impact of spatial blocking between HMIMO users. The derived analytical framework reveals that the DoF of HMIMO in multi-user near-field channels is not in general given by the sum of the DoF of the HMIMO single-user setting because of spatial blocking. Simulation results demonstrate the effectiveness of the proposed method. In the considered case study, the number of DoF reduces by 21.2% on average due to spatial blocking.

查看原文本刊更多论文

多用户近场信道全息MIMO的自由度

全息多输入多输出（HMIMO）是6G通信的一项新兴技术，该技术将多个天线单元集成在有限的空间中。随着HMIMO阵列孔径的扩大，阵列的近场区域急剧扩大，导致更多的用户位于近场区域。这为无线通信创造了新的机会。在这种情况下，HMIMO多用户系统在近场信道的空间自由度评估是一个开放性问题，因为用于评估远场信道自由度的分析方法不能直接应用。在这篇文章中，我们提出了一种计算HMIMO在多用户近场信道中的DoF的新方法。我们首先推导了近场单用户的自由度，然后将分析扩展到多用户场景。在后一种场景中，我们主要关注HMIMO用户之间空间阻塞的影响。推导出的分析框架表明，由于空间阻塞，多用户近场信道中HMIMO的DoF一般不是由HMIMO单用户设置的DoF之和给出的。仿真结果验证了该方法的有效性。在考虑的案例研究中，由于空间阻塞，DoF的数量平均减少了21.2%。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文求助全文

来源期刊

IEEE Communications Letters 工程技术-电信学

CiteScore

8.10

自引率

7.30%

发文量

590

审稿时长

2.8 months

期刊介绍： The IEEE Communications Letters publishes short papers in a rapid publication cycle on advances in the state-of-the-art of communication over different media and channels including wire, underground, waveguide, optical fiber, and storage channels. Both theoretical contributions (including new techniques, concepts, and analyses) and practical contributions (including system experiments and prototypes, and new applications) are encouraged. This journal focuses on the physical layer and the link layer of communication systems.