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Fluid reconfigurable intelligent surfaces (FRIS) extend conventional reconfigurable intelligent surfaces (RIS) by adding spatial reconfigurability through switchable apertures, pattern-reconfigurable units, fluidic conductive materials, or…

Information Theory · Computer Science 2026-05-22 Xusheng Zhu , Kai-Kit Wong , Sai Xu , Hao Xu , Wen Chen , Hyundong Shin

Reconfigurable intelligent surfaces (RIS) as an effective technique for intelligently manipulating channel paths through reflection to serve desired users. Full-duplex (FD) systems, enabling simultaneous transmission and reception from a…

Information Theory · Computer Science 2023-11-08 Li-Hsiang Shen , Chia-Jou Ku , Kai-Ten Feng

Reconfigurable intelligent surface (RIS) is a recent low-cost and energy-efficient technology with potential applicability for future wireless communications. Performance gains achieved by employing RIS directly depend on accurate channel…

Signal Processing · Electrical Eng. & Systems 2024-12-24 Paulo R. B. Gomes , Amarilton L. Magalhães , André L. F. de Almeida

This paper investigates the reconfigurable reflecting surface (RIS)-aided multiple-input-single-output (MISO) systems with imperfect channel state information (CSI), where RIS-related channels are modeled by Rician fading. Considering the…

Information Theory · Computer Science 2021-07-13 Kangda Zhi , Cunhua Pan , Hong Ren , Kezhi Wang , Maged Elkashlan

Although reconfigurable intelligent surfaces (RISs) can improve the performance of wireless networks by smartly reconfiguring the radio environment, existing passive RISs face two key challenges, i.e., double-fading attenuation and…

Signal Processing · Electrical Eng. & Systems 2023-10-05 Wen Wang , Wanli Ni , Hui Tian , Naofal Al-Dhahir

Active reconfigurable intelligent surface (ARIS) is a newly emerging RIS technique that leverages radio frequency (RF) reflection amplifiers to empower phase-configurable reflection elements (REs) in amplifying the incident signal. Thereby,…

Signal Processing · Electrical Eng. & Systems 2023-11-07 Hao Chen , Nanxi Li , Ruizhe Long , Ying-Chang Liang

This paper proposes a novel pattern-reconfigurable fluid reconfigurable intelligent surface (FRIS) framework, where each fluid element can dynamically adjust its radiation pattern based on instantaneous channel conditions. To evaluate its…

Information Theory · Computer Science 2025-08-14 Han Xiao , Xiaoyan Hu , Kai-Kit Wong , Xusheng Zhu , Hanjiang Hong , Chan-Byoung Chae

Intelligent surfaces comprising of cost effective, nearly passive, and reconfigurable unit elements are lately gaining increasing interest due to their potential in enabling fully programmable wireless environments. They are envisioned to…

Information Theory · Computer Science 2022-05-26 George C. Alexandropoulos , Evangelos Vlachos

A fluid reconfigurable intelligent surface (fRIS)-aided integrated sensing and communication (ISAC) system is proposed to enhance multi-target sensing and multi-user communication. Unlike the conventional RIS, the fRIS employs movable…

Signal Processing · Electrical Eng. & Systems 2026-01-08 Junjie Ye , Peichang Zhang , Xiao-Peng Li , Lei Huang , Yuanwei Liu

The reconfigurable intelligent surface (RIS) technology is a promising enabler for millimeter wave (mmWave) wireless communications, as it can potentially provide spectral efficiency comparable to the conventional massive multiple-input…

Information Theory · Computer Science 2022-02-22 Xuemeng Zhou , Zhiyu Yang , Tianyi Zhang , Yi Jiang

Reconfigurable intelligent surface (RIS) provides a promising way to build programmable wireless transmission environments. Owing to the massive number of controllable reflecting elements on the surface, RIS is capable of providing…

Information Theory · Computer Science 2022-10-03 Xiaoyan Ma , Yuguang Fang , Haixia Zhang , Shuaishuai Guo , Dongfeng Yuan

Reconfigurable intelligent surfaces (RISs) are considered as potential technologies for the upcoming sixth-generation (6G) wireless communication system. Various benefits brought by deploying one or multiple RISs include increased spectrum…

Signal Processing · Electrical Eng. & Systems 2021-04-16 Jiguang He , Nhan Thanh Nguyen , Rafaela Schroeder , Visa Tapio , Joonas Kokkoniemi , Markku Juntti

This paper investigates the uplink cascaded channel estimation for intelligent-reflecting-surface (IRS)-assisted multi-user multiple-input-single-output systems. We focus on a sub-6 GHz scenario where the channel propagation is not sparse…

Signal Processing · Electrical Eng. & Systems 2022-09-07 Huayan Guo , Vincent K. N. Lau

This paper presents a physics-based channel modeling and optimization framework for reconfigurable intelligent surface (RIS)-assisted downlink multi-user multiple-input single-output (MU-MISO) communication systems in site-specific…

Signal Processing · Electrical Eng. & Systems 2026-03-24 Ziqi Liu , Wei Yu , Sean Victor Hum

Active reconfigurable intelligent surface (RIS) emerges as an effective technique to resist the double-fading attenuation of passive RIS. By embedding with power harvesting function, it further evolves to zero-power active RIS, which can…

Information Theory · Computer Science 2025-10-17 Xiao Zheng , Wenchi Cheng , Jingqing Wang , Zhuohui Yao , Jiangzhou Wang

Reconfigurable Intelligent Surface (RIS) technology has emerged as a key enabler for future wireless communications. However, its potential is constrained by the difficulty of acquiring accurate user-to-RIS channel state information (CSI),…

Signal Processing · Electrical Eng. & Systems 2026-04-20 Md. Shahriar Sadid , Ali A. Nasir , Saad Al-Ahmadi , Samir Al-Ghadhban

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

Orthogonal multi-user multiple-input multiple-output (MU-MIMO) channels allow for optimum performance with simplified precoding/equalization, and they achieve maximum multiplexing gain which is shared fairly among users. Reconfigurable…

Information Theory · Computer Science 2023-05-01 Juan Vidal Alegria , Fredrik Rusek

Cell-free (CF) massive multiple-input multiple-output (MIMO) and reconfigurable intelligent surface (RIS) are two promising technologies for realizing future beyond-fifth generation (B5G) networks. In this paper, we consider a practical…

Information Theory · Computer Science 2023-06-16 Enyu Shi , Jiayi Zhang , Derrick Wing Kwan Ng , Bo Ai

This paper considers the reconfigurable intelligent surface (RIS)-assisted multi-user communications, where an RIS is used to assist the base station (BS) for serving multiple users. The RIS consisting of passive reflecting elements can…

Information Theory · Computer Science 2022-12-01 Yu-Tse Wu , Kuang-Hao Liu