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This paper explores the integration of reconfigurable intelligent surfaces (RISs) into cell-free massive multiple-input-multiple-output (CF-mMIMO) networks operating in FR1 and FR3 frequency bands. We present a comprehensive framework for…

Signal Processing · Electrical Eng. & Systems 2026-04-21 Alejandro de la Fuente , Fernando Galindo , Uriel García-Bárbulo , Sandra-Noemy Arana-Alegre , Jan García-Morales

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

Reconfigurable intelligent surface (RIS) is a novel meta-material which can form a smart radio environment by dynamically altering reflection directions of the impinging electromagnetic waves. In the prior literature, the inter-RIS links…

Information Theory · Computer Science 2024-03-13 Kaizhe Xu , Jiajia Guo , Jun Zhang , Shi Jin , Shaodan Ma

Reconfigurable intelligent surface (RIS) has entered the public consciousness as a promising technology for enhancing the performance of future wireless communication systems by dynamically constructing the wireless channels. In this…

Information Theory · Computer Science 2023-03-02 Pingping Zhang , Shiqi Gong , Shaodan Ma

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

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

This paper investigates double RIS-assisted MIMO communication systems over Rician fading channels with finite scatterers, spatial correlation, and the existence of a double-scattering link between the transceiver. First, the statistical…

Information Theory · Computer Science 2023-09-11 Ha An Le , Trinh Van Chien , Van Duc Nguyen , Wan Choi

A cell-free network merged with active reconfigurable reflecting surfaces (RIS) is investigated in this paper. Based on the imperfect channel state information (CSI), the aggregated channel from the user to the access point (AP) is…

Signal Processing · Electrical Eng. & Systems 2024-02-23 Mahdi Eskandari , Huiling Zhu , Jiangzhou Wang

Cell-free massive MIMO (multiple-input multiple-output) is a promising network architecture for beyond 5G systems, which can particularly offer more uniform data rates across the coverage area. Recent works have shown how reconfigurable…

Signal Processing · Electrical Eng. & Systems 2024-09-25 Özlem Tuğfe Demir , Emil Björnson

A double self-sustainable reconfigurable intelligent surfaces (RISs) assisted multi-user multiple input multiple output (MIMO) system is investigated. Two RISs are equipped with energy harvesting circuit to achieve self-sustainable…

Information Theory · Computer Science 2024-05-08 Ji Wang , Suhong Luo , Yixuan Li , Wenwu Xie , Xingwang Li , Arumugam Nallanathan

This paper proposes a two-stage approach for passive and active beamforming in multiple-input multiple-output (MIMO) interference channels (ICs) assisted by a beyond-diagonal reconfigurable intelligent surface (BD-RIS). In the first stage,…

Information Theory · Computer Science 2025-03-26 Ignacio Santamaria , Mohammad Soleymani , Eduard Jorswieck , Jesus Gutierrez

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

It is challenging to precisely configure the phase shifts of the reflecting elements at the reconfigurable intelligent surface (RIS) due to inherent hardware impairments (HIs). In this paper, the mean square error (MSE) performance is…

Information Theory · Computer Science 2022-08-17 Jingwen Zhao , Ming Chen , Cunhua Pan , Zhiyang Li , Gui Zhou , Xiao Chen

We consider a practical spatially correlated reconfigurable intelligent surface (RIS)-aided cell-free (CF) massive multiple-input-multiple-output (mMIMO) system with multi-antenna access points (APs) over spatially correlated Rician fading…

Information Theory · Computer Science 2022-09-29 Enyu Shi , Jiayi Zhang , Zhe Wang , Derrick Wing Kwan Ng , Bo Ai

Double-reconfigurable intelligent surface (RIS) is a promising technique, achieving a substantial gain improvement compared to single-RIS techniques. However, in double-RIS-aided systems, accurate channel estimation is more challenging than…

Information Theory · Computer Science 2022-11-30 Songjie Yang , Wanting Lyu , Yue Xiu , Zhongpei Zhang , Chau Yuen

Transmissive reconfigurable intelligent surfaces (RIS) represent a transformative architecture for future wireless networks, enabling a paradigm shift from traditional costly base stations to low-cost, energy-efficient transmitters. This…

Information Theory · Computer Science 2025-11-17 Zhengwei Jiang , Yufeng Zhou , Xusheng Zhu , Wen Chen , Qingqing Wu , Kai-Kit Wong

Reconfigurable Intelligent Surfaces (RISs) constitute a promising emerging technology that enables wireless systems to control the propagation environment to enhance diverse communication objectives. To mitigate double-fading attenuation in…

Signal Processing · Electrical Eng. & Systems 2025-04-01 Panagiotis Gavriilidis , Deepak Mishra , Besma Smida , Ertugrul Basar , Chau Yuen , George C. Alexandropoulos

Cell-free systems can effectively eliminate the inter-cell interference by enabling multiple base stations (BSs) to cooperatively serve users without cell boundaries at the expense of high costs of hardware and power sources due to the…

Information Theory · Computer Science 2020-11-18 Yutong Zhang , Boya Di , Hongliang Zhang , Jinlong Lin , Yonghui Li , Lingyang Song

Reconfigurable Intelligent Surface (RIS) has becoming a useful tool in future wireless communication systems for close-distance communication network. This paper we use Reconfigurable Intelligent Surface (RIS) for downlink multi-user…

Information Theory · Computer Science 2021-02-02 RuiTianYi Lu

Reconfigurable intelligent surfaces (RIS) can be crucial in next-generation communication systems. However, designing the {RIS} phases according to the instantaneous channel state information (CSI) can be challenging in practice due to the…

Information Theory · Computer Science 2023-09-26 Athira Subhash , Abla Kammoun , Ahmed Elzanaty , Sheetal Kalyani , Yazan H. Al-Badarneh , Mohamed-Slim Alouini