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Reconfigurable intelligent surfaces (RIS)-assisted cell-free massive multiple-input multiple-output (CF mMIMO) systems have emerged as a promising technology for sixth-generation communication systems. These systems capitalize on RIS to…

Signal Processing · Electrical Eng. & Systems 2024-12-24 Yu Lu , Jiayi Zhang , Enyu Shi , Peng Zhang , Derrick Wing Kwan Ng , Dusit Niyato , Bo Ai

Although reconfigurable intelligent surface (RIS) is a promising technology for shaping the propagation environment, it consists of a single-layer structure within inherent limitations regarding the number of beam steering patterns. Based…

A reconfigurable intelligent surface (RIS) can shape the radio propagation by passively changing the directions of impinging electromagnetic waves. The optimal control of the RIS requires perfect channel state information (CSI) of all the…

Signal Processing · Electrical Eng. & Systems 2020-02-18 Jiguang He , Markus Leinonen , Henk Wymeersch , Markku Juntti

Reconfigurable Intelligent Surfaces (RIS) represent a transformative technology for sixth-generation (6G) wireless communications, but it suffers from a significant limitation, namely the double-fading attenuation. Active RIS has emerged as…

Information Theory · Computer Science 2025-04-23 Yang Cao , Wenchi Cheng , Jingqing Wang , Wei Zhang

Reconfigurable intelligent surface (RIS) is a promising technology that can reshape the electromagnetic environment in wireless networks, offering various possibilities for enhancing wireless channels. Motivated by this, we investigate the…

Information Theory · Computer Science 2024-09-02 Shengguo Meng , Wankai Tang , Weicong Chen , Jifeng Lan , Qun Yan Zhou , Yu Han , Xiao Li , Shi Jin

Reconfigurable intelligent surface (RIS) has recently drawn intensive attention due to its potential of simultaneously realizing high spectral and energy efficiency in a sustainable way. This paper focuses on the design of efficient…

Information Theory · Computer Science 2023-03-17 Wei Jiang , Hans D. Schotten

The paper studies a reconfigurable intelligent surface (RIS)-assisted multi-user uplink massive multiple-input multiple-output (MIMO) system with imperfect hardware. At the RIS, the paper considers phase noise, while at the base station,…

Information Theory · Computer Science 2022-08-18 Zhangjie Peng , Xianzhe Chen , Cunhua Pan , Maged Elkashlan , Jiangzhou Wang

Integrating cell-free massive multiple-input multiple-output (MIMO) with simultaneous transmitting and reflecting reconfigurable intelligent surfaces (STAR-RISs) can provide ubiquitous connectivity and enhance coverage. This paper explores…

Information Theory · Computer Science 2025-03-18 Jun Qian , Ross Murch , Khaled B. Letaief

Reconfigurable Intelligent Surfaces (RIS) are passive or semi-passive heterogeneous metasurfaces and consist of many tunable elements. RIS is gaining momentum as a promising new technology to enable transforming the propagation environment…

Signal Processing · Electrical Eng. & Systems 2022-01-06 Pooja Nuti , Elyes Balti , Brian L. Evans

The incorporation of reconfigurable intelligent surface (RIS) into massive multiple-input-multiple-output (mMIMO) systems can unleash the potential of next-generation networks by improving the performance of user equipments (UEs) in service…

Information Theory · Computer Science 2022-09-12 Anastasios Papazafeiropoulos , Ioannis Krikidis , Pandelis Kourtessis

Reconfigurable intelligent surface is a potential technology component of future wireless networks due to its capability of shaping the wireless environment. The promising MIMO systems in terms of extended coverage and enhanced capacity…

Information Theory · Computer Science 2022-07-07 Paulo R. B. Gomes , Gilderlan T. de Araújo , Bruno Sokal , André L. F. de Almeida , Behrooz Makki , Gábor Fodor

We consider a reconfigurable intelligent surface (RIS) assisted cell-free massive multiple-input multiple-output non-orthogonal multiple access (NOMA) system, where each access point (AP) serves all the users with the aid of the RIS. We…

Information Theory · Computer Science 2024-09-18 Malay Chakraborty , Ekant Sharma , Himal A. Suraweera , Hien Quoc Ngo

Reconfigurable intelligent surface (RIS)-assisted cell-free (CF) multiple-input multiple-output (MIMO) networks can significantly enhance system performance. However, the extensive deployment of RIS elements imposes considerable channel…

Signal Processing · Electrical Eng. & Systems 2025-06-30 Hongqin Ke , Jindan Xu , Wei Xu , Chau Yuen , Zhaohua Lu

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

This paper provides a theoretical framework for understanding the performance of reconfigurable intelligent surface (RIS)-aided massive multiple-input multiple-output (MIMO) with zero-forcing (ZF) detectors under imperfect channel state…

Information Theory · Computer Science 2021-11-03 Kangda Zhi , Cunhua Pan , Gui Zhou , Hong Ren , Maged Elkashlan , Robert Schober

This paper considers a simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS)-aided cell-free massive multiple-input multiple-output (CF-mMIMO) system, accounting for imperfect hardware in spatially…

Information Theory · Computer Science 2024-08-27 Zeping Sui , Hien Quoc Ngo , Michail Matthaiou

This paper considers Cell-Free Massive Multiple Input Multiple Output (MIMO) systems with the assistance of an RIS for enhancing the system performance. Distributed maximum-ratio combining (MRC) is considered at the access points (APs). We…

Information Theory · Computer Science 2021-09-17 Trinh Van Chien , Hien Quoc Ngo , Symeon Chatzinotas , Marco Di Renzo , Björn Ottersten

This paper studies a reconfigurable intelligent surface (RIS)-assisted cell-free massive multiple-input multiple-output (CF-mMIMO) system with multiple RISs. Joint design of transmit precoding, RIS coefficients, and receive combining is…

Signal Processing · Electrical Eng. & Systems 2025-10-21 Navid Reyhanian , Reza Ghaderi Zefreh , Parisa Ramezani , Emil Bjornson

In this work, we address the energy efficiency (EE) maximization problem in a downlink communication system utilizing reconfigurable intelligent surface (RIS) in a multi-user massive multiple-input multiple-output (mMIMO) setup with…

Information Theory · Computer Science 2023-12-22 Wilson de Souza Junior , Taufik Abrao

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