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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

The emerging reflecting intelligent surface (RIS) technology promises to enhance the capacity of wireless communication systems via passive reflect beamforming. However, the product path loss limits its performance gains. Fully-connected…

Information Theory · Computer Science 2025-03-26 Konstantinos Ntougias , Symeon Chatzinotas , Ioannis Krikidis

Practical hardware limitations often impose a reduced number of available phase shifts at the elements of a reconfigurable intelligent surface (RIS). Most works often assume continuous phase-shits at the RIS elements for the transmit and…

Information Theory · Computer Science 2023-04-20 Nuno Souto

With the explosive growth of data traffic and the ubiquitous connectivity of wireless devices, the energy demands of wireless networks have inevitably escalated. Reconfigurable intelligent surface (RIS) has emerged as a promising solution…

Signal Processing · Electrical Eng. & Systems 2025-12-16 Hongyi Luo , Wenyu Song , Daniel K. C. So , Zahra Mobini , Zhiguo Ding

Terahertz (THz) communications will be pivotal in sixth-generation (6G) wireless networks, offering significantly wider bandwidths and higher data rates. However, the unique propagation characteristics of the THz frequency band, such as…

Networking and Internet Architecture · Computer Science 2024-09-17 Waqas Khalid , Heejung Yu , Farman Ali , Huiping Huang

Reconfigurable Intelligent Surfaces (RIS)-empowered communication has emerged as a transformative technology for next generation wireless networks, enabling the programmable shaping of the propagation environment. However, conventional RISs…

Information Theory · Computer Science 2025-07-23 Recep Akif Tasci , Panagiotis Gavriilidis , Ertugrul Basar , George C. Alexandropoulos

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

In this paper, we investigate the performance of multiple-input multiple-output (MIMO) fading channels assisted by a reconfigurable intelligent surface (RIS), through the employment of partition-based RIS schemes. The proposed schemes are…

Information Theory · Computer Science 2023-05-09 Andreas Nicolaides , Constantinos Psomas , Ghassan M. Kraidy , Sheng Yang , Ioannis Krikidis

Reconfigurable Intelligent Surface (RIS) is a promising solution to reconfigure the wireless environment in a controllable way. To compensate for the double-fading attenuation in the RIS-aided link, a large number of passive reflecting…

Information Theory · Computer Science 2021-03-02 Ruizhe Long , Ying-Chang Liang , Yiyang Pei , Erik G. Larsson

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

We consider a multi-user multiple-input single-output (MISO) communications system which is assisted by a hybrid active-passive reconfigurable intelligent surface (RIS). Unlike conventional passive RISs, hybrid RIS is equipped with a few…

Information Theory · Computer Science 2022-03-22 Nhan Thanh Nguyen , Van-Dinh Nguyen , Qingqing Wu , Antti Tolli , Symeon Chatzinotas , Markku Juntti

We consider a practical spatially correlated reconfigurable intelligent surface (RIS)-aided cell-free (CF) massive multiple-input-multiple-output (mMIMO) system with multi-antenna access points (APs) over spatially correlated Rician fading…

Information Theory · Computer Science 2022-09-29 Enyu Shi , Jiayi Zhang , Zhe Wang , Derrick Wing Kwan Ng , Bo Ai

An emerging technology to enhance the spectral efficiency (SE) and energy efficiency (EE) of wireless communication systems is reconfigurable intelligent surface (RIS), which is shown to be very powerful in single-carrier systems. However,…

Information Theory · Computer Science 2024-01-23 Mohammad Soleymani , Ignacio Santamaria , Aydin Sezgin , Eduard Jorswieck

A novel hybrid active-passive reconfigurable intelligent surface (RIS) transmitter enabled downlink multi-user communication system is investigated. Specifically, RISs are exploited to serve as transmitter antennas, where each element can…

Information Theory · Computer Science 2024-03-05 Ao Huang , Xidong Mu , Li Guo , Guangyu Zhu

Integrating the reconfigurable intelligent surface in a cell-free (RIS-CF) network is an effective solution to improve the capacity and coverage of future wireless systems with low cost and power consumption. The reflecting coefficients of…

Signal Processing · Electrical Eng. & Systems 2021-03-10 Quang Nhat Le , Van-Dinh Nguyen , Octavia A. Dobre , Ruiqin Zhao

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 letter considers an active reconfigurable intelligent surface (RIS)-aided multi-user uplink massive multipleinput multiple-output (MIMO) system with low-resolution analog-to-digital converters (ADCs). The letter derives the closedform…

Information Theory · Computer Science 2024-04-23 Zhangjie Peng , Zecheng Lu , Xue Liu , Cunhua Pan , Jiangzhou Wang

Reconfigurable intelligent surface (RIS) assisted millimeter-wave (mmWave) communication systems relying on hybrid beamforming structures are capable of achieving high spectral efficiency at a low hardware complexity and low power…

Signal Processing · Electrical Eng. & Systems 2022-01-13 Chenghao Feng , Wenqian Shen , Jianping An , Lajos Hanzo

In this paper, we investigate an intelligent reflecting surface (IRS) assisted cell-free multiple input multiple output (MIMO) communication system, where distributed multiple IRSs are dedicated deployed to assist distributed multiple base…

Information Theory · Computer Science 2021-08-18 Xie Xie , Chen He , Xiaoya Li , Kun Yang , Z. Jane Wang

TeraHertz (THz) communications can satisfy the high data rate demand with massive bandwidth. However, severe path attenuation and hardware imperfection greatly alleviate its performance. Therefore, we utilize the reconfigurable intelligent…

Information Theory · Computer Science 2022-03-22 Hongyang Du , Jiayi Zhang , Ke Guan , Dusit Niyato , Huiying Jiao , Zhiqin Wang , Thomas Kürner