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This paper investigates reconfigurable intelligent surface (RIS)-aided frequency division duplexing (FDD) communication systems. Since the downlink and uplink signals are simultaneously transmitted in FDD, the phase shifts at the RIS should…

Information Theory · Computer Science 2024-01-23 Gyoseung Lee , Hyeongtaek Lee , Donghwan Kim , Jaehoon Chung , A. Lee. Swindlehurst , Junil Choi

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

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

Reconfigurable intelligent surface (RIS) has been anticipated to be a novel cost-effective technology to improve the performance of future wireless systems. In this paper, we investigate a practical RIS-aided multiple-input-multiple-output…

Information Theory · Computer Science 2023-03-23 Jintao Wang , Shiqi Gong , Qingqing Wu , Shaodan Ma

Reconfigurable intelligent surface (RIS)-aided cell-free (CF) massive multiple-input multiple-output (mMIMO) is a promising technology for further improving spectral efficiency (SE) with low cost and power consumption. However, conventional…

Information Theory · Computer Science 2025-12-02 Yizhuo Li , Jiakang Zheng , Bokai Xu , Yiyang Zhu , Jiayi Zhang , Dusit Niyato , Bo Ai

This work considers a reconfigurable intelligent surface (RIS)-aided cell-free massive multiple-input multiple-output (MIMO) system with RIS spatial correlation and electromagnetic interference (EMI). We propose a two-phase channel…

Information Theory · Computer Science 2024-11-18 Jun Qian , Chi Zhang , Khaled B. Letaief , Ross Murch

Reconfigurable intelligent surfaces (RISs) have attracted great attention as a potential beyond 5G technology. These surfaces consist of many passive elements of metamaterials whose impedance can be controllable to change the phase,…

Information Theory · Computer Science 2021-09-09 Özlem Tuğfe Demir , Emil Björnson

Cell-Free Massive multiple-input multiple-output (MIMO) and reconfigurable intelligent surface (RIS) are two promising technologies for application to beyond-5G networks. This paper considers Cell-Free Massive MIMO systems with the…

Information Theory · Computer Science 2021-12-20 Trinh Van Chien , Hien Quoc Ngo , Symeon Chatzinotas , Marco Di Renzo , Björn Ottersten

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

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

This paper considers a multi-user multiple-input multiple-output (MU-MIMO) system where the downlink communication between a base station (BS) and multiple user equipments (UEs) is aided by a reconfigurable intelligent surface (RIS). We…

Signal Processing · Electrical Eng. & Systems 2024-09-24 Parisa Ramezani , Yasaman Khorsandmanesh , Emil Björnson

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

The technology of Reconfigurable Intelligent Surfaces (RISs) has lately attracted considerable interest from both academia and industry as a low-cost solution for coverage extension and signal propagation control. In this paper, we study…

Information Theory · Computer Science 2022-08-03 Konstantinos D. Katsanos , Paolo Di Lorenzo , George C. Alexandropoulos

Reconfigurable intelligent surfaces (RISs) have huge potential to improve spectral and energy efficiency in future wireless systems at a minimal cost. However, early prototype results indicate that deploying hundreds or thousands of…

Signal Processing · Electrical Eng. & Systems 2024-12-12 Eduard E. Bahingayi , Nemanja Stefan Perović , Le-Nam Tran

In this paper, a reconfigurable intelligent surface (RIS) assisted cell free massive MIMO (CFmMIMO) framework is designed to enhance physical layer security (PLS) and mitigate multi user (MU) interference in next generation wireless…

Signal Processing · Electrical Eng. & Systems 2025-12-16 Sumeyra Hassan , Bin Li , Yalcin Sadi , Erdal Panayirci , H. Vincent Poor

Reconfigurable Intelligent Surfaces (RISs) are an emerging technology for future wireless communication systems, enabling improved coverage in an energy efficient manner. RISs are usually metasurfaces, constituting of two-dimensional…

Information Theory · Computer Science 2022-03-28 Konstantinos D. Katsanos , Nir Shlezinger , Mohammadreza F. Imani , George C. Alexandropoulos

Simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS)-aided cell-free massive multiple-input multiple-output (CF-mMIMO) systems are investigated under spatially correlated fading channels using realistic…

Information Theory · Computer Science 2025-01-06 Zeping Sui , Hien Quoc Ngo , Michail Matthaiou , Lajos Hanzo

Thanks to the strong ability against the inter-cell interference, cell-free network is considered as a promising technique to improve network capacity. However, further capacity improvement requires to deploy more base stations (BSs) with…

Signal Processing · Electrical Eng. & Systems 2021-09-01 Zijian Zhang , Linglong Dai

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

We investigate a reconfigurable intelligent surface (RIS)-aided multi-user massive multiple-input multi-output (MIMO) system where low-resolution digital-analog converters (DACs) are configured at the base station (BS) in order to reduce…

Information Theory · Computer Science 2021-08-24 Jianxin Dai , Yuanyuan Wang , Cunhua Pan , Kangda Zhi , Hong Ren , Kezhi Wang