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In this paper, we analyse the performance of a reconfigurable intelligent surface (RIS) aided system where the RIS is divided into subsurfaces. Each subsurface is designed specifically for one user, who is served on their own frequency…

Signal Processing · Electrical Eng. & Systems 2026-03-12 Amy S. Inwood , Peter J. Smith , Philippa A. Martin , Graeme K. Woodward

In this letter, we study efficient uplink channel estimation design for a simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) assisted two-user communication systems. We first consider the time switching…

Information Theory · Computer Science 2021-12-03 Chenyu Wu , Changsheng You , Yuanwei Liu , Xuemai Gu , Yunlong Cai

An reconfigurable intelligent surface (RIS) can be used to establish line-of-sight (LoS) communication when the direct path is compromised, which is a common occurrence in a millimeter wave (mmWave) network. In this paper, we focus on the…

Signal Processing · Electrical Eng. & Systems 2022-02-25 Dilin Dampahalage , K. B. Shashika Manosha , Nandana Rajatheva , Matti Latva-aho

Novel reconfigurable intelligent surface (RIS) architectures, known as beyond diagonal RISs (BD-RISs), have been proposed to enhance reflection efficiency and expand RIS capabilities. However, their passive nature, non-diagonal reflection…

Signal Processing · Electrical Eng. & Systems 2024-11-28 Nipuni Ginige , Arthur Sousa de Sena , Nurul Huda Mahmood , Nandana Rajatheva , Matti Latva-aho

The deployment of multiple reconfigurable intelligent surfaces (RISs) enhances the propagation environment by improving channel quality, but it also complicates channel estimation. Following the conventional wireless communication system…

Information Theory · Computer Science 2024-11-22 Weicong Chen , Yu Han , Chao-Kai Wen , Xiao Li , Shi Jin

Fluid reconfigurable intelligent surfaces (FRISs) have recently emerged as a promising paradigm for wireless communications, wherein the reflecting elements can dynamically select their effective radiating positions from a dense preset…

Signal Processing · Electrical Eng. & Systems 2026-05-19 Amarilton L. Magalhães , André L. F. de Almeida , George C. Alexandropoulos

To mitigate the effects of shadow fading and obstacle blocking, reconfigurable intelligent surface (RIS) has become a promising technology to improve the signal transmission quality of wireless communications by controlling the…

Information Theory · Computer Science 2021-11-10 Wangyang Xu , Jiancheng An , Yongjun Xu , Chongwen Huang , Lu Gan , Chau Yuen

This work makes the preliminary contribution of studying the asymptotic performance of a multi-user intelligent reflecting surface (IRS) assisted-multiple-input single-output (MISO) downlink system under imperfect CSI. We first extend the…

Information Theory · Computer Science 2020-08-20 Bayan Al-Nahhas , Qurrat-Ul-Ain Nadeem , Anas Chaaban

Recent research has focused on reconfigurable intelligent surface (RIS)-assisted cell-free systems with the goal of enhancing coverage and lowering the cost of cell-free networks. However, current research makes the assumption that the…

Signal Processing · Electrical Eng. & Systems 2022-07-29 Songjie Yang , Chenfei Xie , Mingwei Wang , Zhongpei Zhang

Beyond diagonal reconfigurable intelligent surface (BD-RIS) architectures offer superior beamforming gain over conventional diagonal RISs. However, the channel estimation overhead is the main hurdle for reaping the above gain in practice.…

Signal Processing · Electrical Eng. & Systems 2026-02-25 Rui Wang , Junyuan Gao , Shuowen Zhang , Bruno Clerckx , Liang Liu

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

Reconfigurable intelligent surfaces (RISs) have been recently considered as one of the emerging technologies for future communication systems by leveraging the tuning capabilities of their reflecting elements. In this paper, we investigate…

Signal Processing · Electrical Eng. & Systems 2020-05-27 Dick Carrillo Melgarejo , Charalampos Kalalas , Arthur Sousa de Sena , Pedro H. J. Nardelli

Accurate estimation of the cascaded channel from a user equipment (UE) to a base station (BS) via each reconfigurable intelligent surface (RIS) element is critical to realizing the full potential of the RIS's ability to control the overall…

Signal Processing · Electrical Eng. & Systems 2024-11-08 Özlem Tuğfe Demir , Emil Björnson , Luca Sanguinetti

A communication link aided by a Reconfigurable Intelligent Surface (RIS) is studied, in which the transmitter can control the state of the RIS via a finite-rate control link. Prior work mostly assumed a fixed RIS configuration irrespective…

Information Theory · Computer Science 2019-11-22 Roy Karasik , Osvaldo Simeone , Marco Di Renzo , Shlomo Shamai

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

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

Consider a communication system in which a single antenna user equipment exchanges information with a multi-antenna base station via a reconfigurable intelligent surface (RIS) in the presence of spatially correlated channels and…

Information Theory · Computer Science 2023-12-14 Wen-Xuan Long , Marco Moretti , Andrea Abrardo , Luca Sanguinetti , Rui Chen

Reconfigurable intelligent surfaces (RISs) are eminently suitable for improving the reliability of wireless communications by jointly designing the active beamforming at the base station (BS) and the passive beamforming at the RIS.…

Information Theory · Computer Science 2025-01-23 Qingchao Li , Mohammed El-Hajjar , Ibrahim Hemadeh , Arman Shojaeifard , Lajos Hanzo

Channel estimation is the main hurdle to reaping the benefits promised by the intelligent reflecting surface (IRS), due to its absence of ability to transmit/receive pilot signals as well as the huge number of channel coefficients…

Signal Processing · Electrical Eng. & Systems 2021-06-23 Rui Wang , Liang Liu , Shuowen Zhang , Changyuan Yu

We investigate a multi-user multiple-input multiple-output interference network in the presence of multiple reconfigurable intelligent surfaces (RISs). The entire system is described by using a circuit-based model for the transmitters,…

Information Theory · Computer Science 2021-02-16 Andrea Abrardo , Davide Dardari , Marco Di Renzo , Xuewen Qian