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Cell-free (CF) massive multiple-input multiple-output (mMIMO) is a promising technique for achieving high spectral efficiency (SE) using multiple distributed access points (APs). However, harsh propagation environments often lead to…

Information Theory · Computer Science 2024-05-16 Yiyang Zhu , Enyu Shi , Ziheng Liu , Jiayi Zhang , Bo Ai

We consider a reconfigurable intelligent surface (RIS) assisted multiple-input multiple-output (MIMO) system in the presence of scattering objects. The MIMO transmitter and receiver, the RIS, and the scattering objects are modeled as…

Information Theory · Computer Science 2023-09-19 H. El Hassani , X. Qian , S. Jeong , N. S. Perović , M. Di Renzo , P. Mursia , V. Sciancalepore , X. Costa-Pérez

A multiuser multiple-input multiple-output wireless communication system is analytically studied, which operates with the aid of a reconfigurable intelligent surface (RIS). The intermediate RIS is equipped with multiple elements and…

Information Theory · Computer Science 2021-10-12 Nikolaos I. Miridakis , Theodoros A. Tsiftsis , Guanghua Yang , Panagiotis A. Karkazis , Helen C. Leligou

Reconfigurable intelligent surface (RIS) is a newly-emerged technology that might fundamentally change how wireless networks are operated. Though extensively studied in recent years, the practical limitations of RIS are often neglected when…

Signal Processing · Electrical Eng. & Systems 2023-12-12 Parisa Ramezani , Yasaman Khorsandmanesh , Emil Björnson

In cell-free multiple input multiple output (MIMO) networks, multiple base stations (BSs) collaborate to achieve high spectral efficiency. Nevertheless, high penetration loss due to large blockages in harsh propagation environments is often…

Information Theory · Computer Science 2023-03-16 Chen Chen , Sai Xu , Jiliang Zhang , Jie Zhang

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

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

In this paper, we consider a multi-user multiple-input multiple-output (MIMO) system aided by multiple intelligent reflecting surfaces (IRSs) that are deployed to increase the coverage and, possibly, the rank of the channel. We propose an…

Information Theory · Computer Science 2020-12-22 Andrea Abrardo , Davide Dardari , Marco Di Renzo

Orthogonal multi-user multiple-input multiple-output (MU-MIMO) channels allow for optimum performance with simplified precoding/equalization, and they achieve maximum multiplexing gain which is shared fairly among users. Reconfigurable…

Information Theory · Computer Science 2023-05-01 Juan Vidal Alegria , Fredrik Rusek

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

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 presents a physics-based channel modeling and optimization framework for reconfigurable intelligent surface (RIS)-assisted downlink multi-user multiple-input single-output (MU-MISO) communication systems in site-specific…

Signal Processing · Electrical Eng. & Systems 2026-03-24 Ziqi Liu , Wei Yu , Sean Victor Hum

This paper proposes the joint design of reconfigurable intelligent surfaces (RIS) and zero-forcing (ZF) precoding for the downlink (DL) multiuser multiple-input single-output (MU-MISO) setup in millimeter-wave (mmWave) bands, where ZF is…

Signal Processing · Electrical Eng. & Systems 2026-05-13 Ainna Yue Moreno-Locubiche , Josep Vidal , Antonio Pascual-Iserte , Olga Muñoz

We investigate the performance of a multiple reconfigurable intelligence surface (RIS)-aided millimeter wave (mmWave) beamspace multiple-input multiple-output (MIMO) system with multiple users (UEs). We focus on a challenging scenario in…

Information Theory · Computer Science 2025-05-21 Zaid Abdullah , Mario R. Camana , Abuzar B. M. Adam , Chandan K. Sheemar , Eva Lagunas , Symeon Chatzinotas

This paper presents a scalable beamforming design for maximizing the spectral efficiency (SE) of multi-reconfigurable intelligent surface (RIS)-aided communications through joint optimization of the precoder and RIS phase shifts in…

Signal Processing · Electrical Eng. & Systems 2026-01-28 Mintaek Oh , Jinseok Choi

Reconfigurable intelligent surface (RIS) is a promising technology to enhance the spectral efficiency of wireless communication systems. By optimizing the RIS elements, the performance of the overall system can be improved. Yet, in contrast…

Information Theory · Computer Science 2023-10-13 Mohammad Soleymani , Ignacio Santamaria , Aydin Sezgin , Eduard Jorswieck

This paper investigates the reconfigurable reflecting surface (RIS)-aided multiple-input-single-output (MISO) systems with imperfect channel state information (CSI), where RIS-related channels are modeled by Rician fading. Considering the…

Information Theory · Computer Science 2021-07-13 Kangda Zhi , Cunhua Pan , Hong Ren , Kezhi Wang , Maged Elkashlan

In this paper, we consider and study a cell-free massive MIMO (CF-mMIMO) system aided with reconfigurable intelligent surfaces (RISs), where a large number of access points (APs) cooperate to serve a smaller number of users with the help of…

Information Theory · Computer Science 2021-05-17 Bayan Al-Nahhas , Mohanad Obeed , Anas Chaaban , Md. Jahangir Hossain

Massive multiple-input multiple-output (MIMO) and reconfigurable intelligent surface (RIS) are two promising technologies for 5G-and-beyond wireless networks, capable of providing large array gain and multiuser spatial multiplexing. Without…

Information Theory · Computer Science 2021-09-07 Trinh Van Chien , Hien Quoc Ngo , Symeon Chatzinotas , Björn Ottersten

Reconfigurable intelligent surface (RIS) can be employed in a cell-free system to create favorable propagation conditions from base stations (BSs) to users via configurable elements. However, prior works on RIS-aided cell-free system…

Information Theory · Computer Science 2022-08-15 Xu Gan , Caijun Zhong , Chongwen Huang , Zhaohui Yang , Zhaoyang Zhang