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In this paper, a channel estimation technique for reconfigurable intelligent surface (RIS)-aided multi-user multiple-input single-output communication systems is proposed. By deploying a small number of active elements at the RIS, the RIS…

Information Theory · Computer Science 2023-02-09 Gyoseung Lee , Hyeongtaek Lee , Jaeky Oh , Jaehoon Chung , Junil Choi

This paper investigates the fundamental tradeoff between reconfigurable intelligent surfaces (RISs) and network-controlled repeaters (NCRs) in terms of achievable signal-to-noise ratio (SNR). Considering an uplink system with a…

Signal Processing · Electrical Eng. & Systems 2026-03-23 Özlem Tuğfe Demir , Ozan Alp Topal , Cicek Cavdar , Emil Björnson

Different from conventional passive reconfigurable intelligent surfaces (RISs), incident signals and thermal noise can be amplified at active RISs. By exploiting the amplifying capability of active RISs, noticeable performance improvement…

Information Theory · Computer Science 2025-04-02 Jinho Yang , Hyeongtaek Lee , Junil Choi

This paper investigates a wireless-powered hybrid reflecting intelligent surface (hybrid RIS)-assisted multiple access system, where the RIS can harvest energy from energy station (ES) transmitted radio frequency signal (RF), and each…

Signal Processing · Electrical Eng. & Systems 2024-02-20 Mingang Yuan , Wenzhe Zhang , Gaofei Huang

Reconfigurable intelligent surfaces (RISs) are widely considered to become an integral part of future wireless communication systems. Various methodologies exist to design such surfaces; however, most consider or require a very large number…

Optimization and Control · Mathematics 2023-09-01 Hans-Dieter Lang , Michel A. Nyffenegger , Heinz Mathis , Xingqi Zhang

This paper considers an antenna structure where a (non-large) array of radiating elements is placed at short distance in front of a reconfigurable intelligent surface (RIS), herein nicknamed reconfigurable intelligent base station (RIBS).…

Information Theory · Computer Science 2024-10-24 Giovanni Interdonato , Francesca Di Murro , Carmen D'Andrea , Giovanni Di Gennaro , Stefano Buzzi

The emerging reflecting intelligent surface (RIS) technology promises to enhance the capacity of wireless communication systems via passive reflect beamforming. However, the product path loss limits its performance gains. Fully-connected…

Information Theory · Computer Science 2025-03-26 Konstantinos Ntougias , Symeon Chatzinotas , Ioannis Krikidis

The reconfigurable intelligent surface (RIS) technology for metasurfaces is ushering in a new paradigm for wireless communication systems. It provides an accessible way for controlling the interaction between electromagnetic waves with the…

Signal Processing · Electrical Eng. & Systems 2026-01-21 P. H. C. de Souza , M. Khazaee , L. L. Mendes

Reconfigurable intelligent surfaces (RIS) have been actively researched as a potential technique for future wireless communications, which intelligently ameliorate the signal propagation environment. In the conventional design, each RIS…

Information Theory · Computer Science 2022-03-17 Qingchao Li , Mohammed El-Hajjar , Ibrahim Hemadeh , Arman Shojaeifard , Alain A. M. Mourad , Bruno Clerckx , Lajos Hanzo

This letter attempts to design a surveillance scheme by adopting an active reconfigurable intelligent surface (RIS). Different from the conventional passive RIS, the active RIS could not only adjust the phase shift but also amplify the…

Information Theory · Computer Science 2024-10-28 Xinyue Hu , Yibo Yi , Kun Li , Hongwei Zhang , Caihong Kai

A point-to-point movable element (ME) enabled reconfigurable intelligent surface (ME-RIS) communication system is investigated, where each element position can be flexibly adjusted to create favorable channel conditions. For maximizing the…

Signal Processing · Electrical Eng. & Systems 2025-03-20 Jingjing Zhao , Qingyi Huang , Kaiquan Cai , Quan Zhou , Xidong Mu , Yuanwei Liu

In traditional Reconfigurable Intelligent Surfaces (RIS) systems, the RIS is mounted on stationary structures like buildings, walls, or posts. They have shown promising results in enhancing the performance of wireless systems like capacity…

Signal Processing · Electrical Eng. & Systems 2024-12-24 I. Zakir Ahmed , Hamid Sadjadpour

Reconfigurable intelligent surface (RIS) is an emerging technique employing metasurface to reflect the signal from the source node to the destination node without consuming any energy. Not only the spectral efficiency but also the energy…

Information Theory · Computer Science 2021-01-29 Qi Gu , Dan Wu , Xin Su , Jing Jin , Yifei Yuan , Jiangzhou Wang

In this paper, we propose a robust secure transmission scheme for an active reconfigurable intelligent surface (RIS) enabled symbiotic radio (SR) system in the presence of multiple eavesdroppers (Eves). In the considered system, the active…

Information Theory · Computer Science 2023-04-14 Bin Lyu , Chao Zhou , Shimin Gong , Dinh Thai Hoang , Ying-chang Liang

To advance towards carbon-neutrality and improve the limited {performance} of conventional passive wireless communications, in this paper, we investigate the integration of noise modulation with zero-energy reconfigurable intelligent…

Information Theory · Computer Science 2025-06-04 Ahmad Massud Tota Khel , Aissa Ikhlef , Zhiguo Ding , Hongjian Sun

Deploying active reflecting elements at the intelligent reflecting surface (IRS) increases signal amplification capability but incurs higher power consumption. Therefore, it remains a challenging and open problem to determine the optimal…

Information Theory · Computer Science 2023-07-03 Qiaoyan Peng , Qingqing Wu , Guangji Chen , Ruiqi Liu , Shaodan Ma , Wen Chen

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

One technology that has the potential to improve wireless communications in years to come is integrated sensing and communication (ISAC). In this study, we take advantage of reconfigurable intelligent surface's (RIS) potential advantages to…

Signal Processing · Electrical Eng. & Systems 2023-08-22 Panpan Li , Yong Niu , Hao Wu , Zhu Han , Guiqi Sun , Ning Wang , Zhangdui Zhong , Bo Ai

We propose a novel concept of hybrid relay-reflecting intelligent surface (HR-RIS), in which a single or few elements are deployed with power amplifiers (PAs) to serve as active relays, while the remaining elements only reflect the incident…

Signal Processing · Electrical Eng. & Systems 2021-05-04 Nhan Thanh Nguyen , Quang-Doanh Vu , Kyungchun Lee , Markku Juntti

Physical layer security in reconfigurable intelligent surface (RIS)-assisted wireless systems can be improved through coordinated control of signal transmission and RIS configuration. In this work, the base station simultaneously transmits…

Signal Processing · Electrical Eng. & Systems 2026-05-27 Mustafa Furkan Beker , Ahmet Muaz Aktas , Sefa Kayraklik , Sultangali Arzykulov