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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

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

Reconfigurable intelligent surfaces (RISs) are widely considered a promising technology for future wireless communication systems. As an important indicator of RIS-assisted communication systems in green wireless communications, energy…

Signal Processing · Electrical Eng. & Systems 2023-10-25 Zhiyi Li , Jida Zhang , Jieao Zhu , Shi Jin , Linglong Dai

In this paper, we consider a reconfigurable intelligent surface (RIS)-assisted multiple-input multiple-output communication system with multiple antennas at both the base station (BS) and the user. We plan to maximize the achievable rate…

Information Theory · Computer Science 2024-05-28 Yaqiong Zhao , Jindan Xu , Wei Xu , Kezhi Wang , Xinquan Ye , Chau Yuen , Xiaohu You

In this letter, we investigate a cell-free network aided by hybrid reconfigurable intelligent surfaces (RISs), which consists of a mixture of passive and active elements that are capable of amplifying and reflecting the incident signal. To…

Signal Processing · Electrical Eng. & Systems 2022-10-05 Wanting Lyu , Yue Xiu , Songjie Yang , Chau Yuen , Zhongpei Zhang

Continuous efforts have been devoted to integrate millimeter wave (mmWave) and terahertz (THz) bands into future communication standards in order to overcome the bandwidth shortage problem and achieve high data rates, primarily through…

Signal Processing · Electrical Eng. & Systems 2026-03-05 Sung Hyuck Hong , Junil Choi

Benefiting from tens of GHz of bandwidth, terahertz (THz) communications has become a promising technology for future 6G networks. However, the conventional hybrid beamforming architecture based on frequency-independent phase-shifters is…

Information Theory · Computer Science 2023-09-22 Yihang Jiang , Ziqin Zhou , Xiaoyang Li , Yi Gong

This paper studies RIS-aided cell-free massive MIMO systems, where multiple RISs are deployed to assist the communication between multiple access points (APs) and multiple users, with either continuous or discrete phase shifts at the RISs.…

Information Theory · Computer Science 2021-12-14 Si-Nian Jin , Dian-Wu Yue , Ha H. Nguyen

Reconfigurable intelligent surface (RIS) refers to a signal reflection surface containing a large number of low-cost passive reflecting elements. RIS can improve the performance of radar and communication systems by dynamically modulating…

Signal Processing · Electrical Eng. & Systems 2023-06-16 Da Li , Bo Tang , Xuyang Wang , Wenjun Wu , Lei Xue

Reconfigurable intelligent surface (RIS) devices have emerged as an effective way to control the propagation channels for enhancing the end-users' performance. However, RIS optimization involves configuring the radio frequency response of a…

Mobile edge computing (MEC) has been regarded as a promising technique to support latencysensitivity and computation-intensive serves. However, the low offloading rate caused by the random channel fading characteristic becomes a major…

Information Theory · Computer Science 2024-03-22 Hao Xie , Dong Li , Bowen Gu

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

Cell-free (CF) massive multiple-input multiple-output (mMIMO) and reconfigurable intelligent surface (RIS) are two advanced transceiver technologies for realizing future sixth-generation (6G) networks. In this paper, we investigate the…

Information Theory · Computer Science 2024-11-19 Enyu Shi , Jiayi Zhang , Ziheng Liu , Yiyang Zhu , Chau Yuen , Derrick Wing Kwan Ng , Marco Di Renzo , Bo Ai

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

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

Reconfigurable intelligent surface (RIS) has emerged as a cost-effective and promising solution to extend the wireless signal coverage and improve the performance via passive signal reflection. Different from existing works which do not…

Information Theory · Computer Science 2023-11-22 Anastasios Papazafeiropoulos , Ahmet M. Elbir , Pandelis Kourtessis , Ioannis Krikidis , Symeon Chatzinotas

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

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

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

We propose a holographic version of a reconfigurable intelligent surface (RIS) and investigate its application to terahertz (THz) massive multiple-input multiple-output systems. Capitalizing on the miniaturization of THz electronic…

Information Theory · Computer Science 2021-03-22 Ziwei Wan , Zhen Gao , Feifei Gao , Marco Di Renzo , Mohamed-Slim Alouini