Beamforming Analysis and Design for Wideband THz Reconfigurable Intelligent Surface Communications
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Le résumé fourni par la source
Reconfigurable intelligent surface (RIS)-aided terahertz (THz) communications have been regarded as a promising candidate for future 6G networks because of its ultra-wide bandwidth and ultra-low power consumption. However, there exists the beam split problem, especially when the base station (BS) or RIS owns the large-scale antennas, which may lead to serious array gain loss. Therefore, in this paper, we investigate the beam split and beamforming design problems in the THz RIS communications. Specifically, we first analyze the beam split effect caused by different RIS sizes, shapes and deployments. On this basis, we apply the fully connected time delayer phase shifter hybrid beamforming (FC-TD-PS-HB) architecture at the BS and deploy distributed RISs to cooperatively mitigate the beam split effect. We aim to maximize the achievable sum rate by jointly optimizing the hybrid analog/digital beamforming, time delays at the BS and reflection coefficients at the RISs. To solve the formulated problem, we first design the analog beamforming and time delays based on different RISs’ physical directions, and then it is transformed into an optimization problem by jointly optimizing the digital beamforming and reflection coefficients. Next, we propose an alternatively iterative optimization algorithm to deal with it. Specifically, for given the reflection coefficients, we propose an iterative algorithm based on the minimum mean square error technique to obtain the digital beamforming. After, we apply Lagrangian dual reformulation (LDR) and multidimensional complex quadratic transform (MCQT) methods to transform the original problem to a quadratically constrained quadratic program, which can be solved by alternating direction method of multipliers (ADMM) technique to obtain the reflection coefficients. Finally, the digital beamforming and reflection coefficients are obtained via repeating the above processes until convergence. Simulation results verify that the proposed scheme can effectively alleviate the beam split effect and improve the system capacity.
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Le contrôle bibliographique ouvert
DOI retrouvé dans Crossref DOI retrouvé ; titre concordant.
- Titre Crossref
- Beamforming Analysis and Design for Wideband THz Reconfigurable Intelligent Surface Communications
- Date Crossref
- 01/08/2023
- Éditeur
- Institute of Electrical and Electronics Engineers (IEEE)
- Type
- journal-article
Ce recoupement confirme des métadonnées liées au DOI. Il ne confirme ni la méthode ni les conclusions de l’étude, et il ne compte pas comme une seconde source scientifique indépendante.
Où se fait cette recherche
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Zhengzhou University pays non établi dans la noticeUniversité ou école supérieure
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Songshan Lake Materials Laboratory pays non établi dans la noticeOrganisme public
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Xidian University State Key Laboratory of Integrated Service Networks pays non établi dans la noticeUniversité ou école supérieure
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Zhejiang Lab pays non établi dans la noticeStructure de recherche
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Zhejiang University pays non établi dans la noticeUniversité ou école supérieure
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Kyushu University Center for Japan-Egypt Cooperation in Science and Technology Égypte (pays nommé en fin d’affiliation)Université ou école supérieure
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RWTH Aachen University Institute for Communication Technologies and Embedded Systems pays non établi dans la noticeUniversité ou école supérieure
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Nanyang Technological University pays non établi dans la noticeUniversité ou école supérieure
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School of Electrical and Information Engineering pays non établi dans la noticeUniversité ou école supérieure
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Songshan Laboratory pays non établi dans la noticeStructure de recherche
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College of Information Science and Electronic Engineering pays non établi dans la noticeUniversité ou école supérieure
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Zhejiang-Singapore Innovation and AI Joint Research Laboratory and Zhejiang Provincial Key Laboratory of Information Processing pays non établi dans la noticeStructure de recherche
Zhengzhou University, Songshan Lake Materials Laboratory et State Key Laboratory of Integrated Service Networks — Xidian University, avec 9 autres affiliations. Pays d’affiliation : Égypte.
Une affiliation ne permet pas de déduire la nationalité d’un auteur.