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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

Cell-free massive MIMO (CF-mMIMO) is expected to provide reliable wireless services for a large number of user equipments (UEs) using access points (APs) distributed across a wide area. When the UEs are battery-powered, uplink energy…

Signal Processing · Electrical Eng. & Systems 2022-05-10 Thomas Choi , Masaaki Ito , Issei Kanno , Takeo Oseki , Kosuke Yamazaki , Andreas F. Molisch

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

Simultaneous Transmitting and Reflecting Reconfigurable Intelligent Surfaces (STAR-RISs) are being explored for sixth-generation (6G) wireless networks. A promising configuration for their deployment is within cell-free massive…

Information Theory · Computer Science 2025-10-10 Jun Qian , Ross Murch , Khaled B. Letaief

We consider a cell-free massive multiple-input multiple-output (MIMO) system with multi-antenna access points and user equipments (UEs) over Weichselberger Rician fading channels with random phase-shifts. More specifically, we investigate…

Information Theory · Computer Science 2022-07-25 Xin Li , Jiayi Zhang , Zhe Wang , Bo Ai , Derrick Wing Kwan Ng

In this paper, we explore the integration of low-power, low-cost stacked intelligent metasurfaces (SIM) into cell-free (CF) massive multiple-input multiple-output (mMIMO) systems to enhance access point (AP) capabilities and address high…

Information Theory · Computer Science 2024-09-20 Enyu Shi , Jiayi Zhang , Yiyang Zhu , Jiancheng An , Chau Yuen , Bo Ai

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 the uplink (UL) of a multi-cell Massive MIMO (multiple-input multiple-output) system with spatially correlated Rician fading channels. The channel model is composed of a deterministic line-of-sight (LoS) path and a…

Information Theory · Computer Science 2018-05-22 Özgecan Özdogan , Emil Björnson , Erik G. Larsson

Cell-free massive MIMO (CF-mMIMO) provides wireless connectivity for a large number of user equipments (UEs) using access points (APs) distributed across a wide area with high spectral efficiency (SE). The energy efficiency (EE) of the…

Information Theory · Computer Science 2022-05-10 Thomas Choi , Masaaki Ito , Issei Kanno , Jorge Gomez-Ponce , Colton Bullard , Takeo Ohseki , Kosuke Yamazaki , Andreas F. Molisch

This paper investigates the downlink power allocation of the simultaneous transmitting and reflecting reconfigurable intelligent surface (STAR-RIS)-assisted cell-free massive multiple-input multiple-output (MIMO) system with multi-antenna…

Information Theory · Computer Science 2025-12-23 Jun Qian , Ross Murch , Khaled B. Letaief

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

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

The rollout of the fifth-generation (5G) networks has raised some concerns about potential health effects from increased exposure to electromagnetic fields (EMF). To address these concerns, we design a novel EMF-aware architecture for…

Signal Processing · Electrical Eng. & Systems 2024-12-10 Mariem Chemingui , Ahmed Elzanaty , Rahim Tafazolli

Motivated by the ever-growing demand for \emph{green} wireless communications and the advantages of \emph{cell-free} (CF) massive multiple-input multiple-output (MIMO) systems, we focus on the design of their downlink for optimal…

Information Theory · Computer Science 2021-02-09 Anastasios Papazafeiropoulos , Hien Q. Ngo , Pandelis Kourtessis , Symeon Chatzinotas , John M. Senior

This paper considers cell-free massive multiple-input multiple-output systems where the multiple-antenna access points (APs) assist the single-antenna user equipments (UEs) by wireless power transfer. The UEs utilize the energy harvested in…

Information Theory · Computer Science 2020-01-28 Özlem Tuğfe Demir , Emil Björnson

Reconfigurable Intelligent Surfaces (RISs) are one of the key emerging 6th Generation (6G) technologies that are expected to improve the link budgets between transmitters and receivers by adding artificial propagation paths. In such…

Information Theory · Computer Science 2022-09-30 Yi Yu , Rita Ibrahim , Dinh-Thuy Phan-Huy

We study the impact of channel aging on the uplink of a cell-free (CF) massive multiple-input multiple-output (mMIMO) system by considering i) spatially-correlated Rician-faded channels; ii) hardware impairments at the access points and…

Information Theory · Computer Science 2024-10-28 Venkatesh Tentu , Dheeraj N Amudala , Anish Chattopadhyay , Rohit Budhiraja

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

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 surfaces (RISs) and cell-free massive multiple-input multiple-output (CF-mMIMO) are effective solutions for mitigating large path loss and inter-cell interference in terahertz (THz) systems. However, passive RISs…

Signal Processing · Electrical Eng. & Systems 2025-05-14 Mario R. Camana , Zaid Abdullah , Carla E. Garcia , Chandan Kumar Sheemar , Eva Lagunas , Symeon Chatzinotas