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The reconfigurable intelligent surface (RIS) has arose an upsurging research interest recently due to its promising outlook in 5G-and-beyond wireless networks. With the assistance of RIS, the wireless propagation environment is no longer…

Signal Processing · Electrical Eng. & Systems 2021-12-28 Zepeng Zhang , Ziping Zhao

Recently, the reconfigurable intelligent surface (RIS), benefited from the breakthrough on the fabrication of programmable meta-material, has been speculated as one of the key enabling technologies for the future six generation (6G)…

Information Theory · Computer Science 2022-06-23 Chongwen Huang , Ronghong Mo , Chau Yuen

This paper investigates the performance of downlink simultaneous transmitting and reflecting reconfigurable intelligent surface (STAR-RIS)-assisted cell-free (CF) massive multiple-input multiple-output (mMIMO) systems, where user equipments…

Information Theory · Computer Science 2023-12-01 Anastasios Papazafeiropoulos , Hien Quoc Ngo , Pandelis Kourtessis , Symeon Chatzinotas

This paper considers an intelligent reflecting sur-face (IRS)-aided simultaneous wireless information and power transfer (SWIPT) network, where multiple users decode data and harvest energy from the transmitted signal of a transmit-ter. The…

Information Theory · Computer Science 2021-03-24 Shayan Zargari , Ata Khalili , Qingqing Wu , Mohammad Robat Mili , Derrick Wing Kwan Ng

Reconfigurable intelligent surfaces enhance wireless systems by reshaping propagation environments. However, dynamic metasurfaces (MSs) with numerous phase-shift elements incur undesired control and hardware costs. In contrast, static MSs…

Signal Processing · Electrical Eng. & Systems 2024-12-30 Ziyuan Zheng , Qingqing Wu , Wen Chen , Xiangming Wu , Weiren Zhu

Reconfigurable intelligent surface (RIS) devices have emerged as an effective way to control the propagation channels for enhancing the end-users' performance. However, RIS optimization involves configuring the radio frequency response of a…

We consider a multi-cell massive MIMO system where a time-division duplex protocol is used to estimate the channel state information via uplink pilots. When maximum ratio combining (MRC) is used at the BSs, the re-use of pilots across cells…

Information Theory · Computer Science 2019-11-26 Meysam Shahrbaf Motlagh , Subhajit Majhi , Patrick Mitran

The concept of reconfigurable intelligent surface (RIS) has been proposed to change the propagation of electromagnetic waves, e.g., reflection, diffraction, and refraction. To accomplish this goal, the phase values of the discrete RIS units…

Signal Processing · Electrical Eng. & Systems 2019-11-11 Jiguang He , Henk Wymeersch , Tachporn Sanguanpuak , Olli Silvén , Markku Juntti

The robust beamforming design in multi-functional reconfigurable intelligent surface (MF-RIS) assisted wireless networks is investigated in this work, where the MF-RIS supports signal reflection, refraction, and amplification to address the…

Computational Engineering, Finance, and Science · Computer Science 2024-12-12 Ailing Zheng , Wanli Ni , Wen Wang , Hui Tian , Chau Yuen

While Reconfigurable Intelligent Surfaces (RISs) constitute one of the most prominent enablers for the upcoming sixth Generation (6G) of wireless networks, the design of efficient RIS phase profiles remains a notorious challenge when large…

Signal Processing · Electrical Eng. & Systems 2024-07-19 Kyriakos Stylianopoulos , Panagiotis Gavriilidis , George C. Alexandropoulos

In this paper, for a single-input multiple-output (SIMO) system aided by a passive reconfigurable intelligent surface (RIS), the joint transmission accomplished by the single transmit antenna and the RIS with multiple controllable…

Information Theory · Computer Science 2023-11-27 Ru-Han Chen , Jing Zhou , Yonggang Zhu , Kai Zhang

This paper considers the application of reconfigurable intelligent surfaces (RISs) (a.k.a. intelligent reflecting surfaces (IRSs)) to assist multiuser multiple-input multiple-output (MIMO) uplink transmission from several multi-antenna user…

Information Theory · Computer Science 2021-09-14 Li You , Jiayuan Xiong , Yufei Huang , Derrick Wing Kwan Ng , Cunhua Pan , Wenjin Wang , Xiqi Gao

This paper investigates a modular beamforming framework for reconfigurable intelligent surface (RIS)-aided multi-user (MU) communications in the near-field regime, built upon a novel antenna architecture integrating an active multi-antenna…

Signal Processing · Electrical Eng. & Systems 2025-08-13 Giulia Torcolacci , Malte Schellmann , Davide Dardari

Full duplex (FD) systems suffer from very high hardware cost and high power consumption to mitigate the self-interference (SI) in the analog domain. Moreover, in millimeter wave (mmWave) they rely on hybrid beamforming (HYBF) as a signal…

Information Theory · Computer Science 2023-06-16 Chandan Kumar Sheemar , Stefano Tomasin , Dirk Slock , Symeon Chatzinotas

Despite extensive research on reconfigurable intelligent surfaces (RISs) in recent years, existing beamforming methods still face significant challenges in achieving flexible and robust beam synthesis, which is an essential capability for a…

Information Theory · Computer Science 2025-05-28 Rujing Xiong , Ke Yin , Jialong Lu , Kai Wan , Tiebin Mi , Robert Caiming Qiu

The sixth-generation (6G) wireless networks will rely on ultra-dense multi-cell deployment to meet the high rate and connectivity demands. However, frequency reuse leads to severe inter-cell interference, particularly for cell-edge users,…

Information Theory · Computer Science 2025-11-18 Shuo Zheng , Shuowen Zhang

In this paper, a discrete reconfigurable intelligent surface (RIS)-assisted spatial shift keying (SSK) multiple-input multiple-output (MIMO) scheme is investigated, in which a direct link between the transmitter and the receiver is…

Information Theory · Computer Science 2024-11-04 Xusheng Zhu , Qingqing Wu , Wen Chen , Xinyuan He , Lexi Xu , Yaxin Zhang

Recent advances in reconfigurable antennas have led to the new concept of the fluid antenna system (FAS) for shape and position flexibility, as another degree of freedom for wireless communication enhancement. This paper explores the…

Signal Processing · Electrical Eng. & Systems 2025-04-15 Jiangong Chen , Yue Xiao , Zhendong Peng , Jing Zhu , Xia Lei , Christos Masouros , Kai-Kit Wong

This paper proposes a reconfigurable intelligent surface (RIS)-aided and angular-based hybrid beamforming (AB-HBF) technique for the millimeter wave (mmWave) massive multiple-input multiple-output (MIMO) systems. The proposed RIS-AB-HBF…

Information Theory · Computer Science 2022-08-16 Ibrahim Yildirim , Asil Koc , Ertugrul Basar , Tho Le-Ngoc

We propose a new reconfigurable intelligent surface (RIS) structure, referred to as interconnected RIS (I-RIS), which allows the RIS elements to be interconnected and share the incident signals using simple binary radio frequency (RF)…

Information Theory · Computer Science 2024-07-17 Sajjad Nassirpour , Naoki Kusashima , Jose Flordelis , Alireza Vahid