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Intelligent reflecting surface (IRS) has emerged as a promising paradigm to improve the capacity and reliability of a wireless communication system by smartly reconfiguring the wireless propagation environment. To achieve the promising…

Signal Processing · Electrical Eng. & Systems 2021-01-12 Yi Wei , Ming-Min Zhao , Min-Jian Zhao , Yunlong Cai

A reconfigurable intelligent surface (RIS) alters the reflection of incoming signals based on the phase-shift configuration assigned to its elements. This feature can be used to improve the signal strength for user equipments (UEs), expand…

Signal Processing · Electrical Eng. & Systems 2024-12-19 Alva Kosasih , Ozlem Tugfe Demir , Emil Bjornson

Reconfigurable intelligent surface (RIS) is a promising technology for future wireless communication systems. Channel estimation (CE) of RIS device is a critical but also challenging issue for its development. The mainstream of existing CE…

Information Theory · Computer Science 2023-08-29 Yanze Zhu , Yang Liu , Qingqing Wu , Changsheng You , Qingjiang Shi

In this paper, we study the transmission design for reconfigurable intelligent surface (RIS)-aided multiuser communication networks. Different from most of the existing contributions, we consider long-term CSI-based transmission design,…

Information Theory · Computer Science 2021-11-25 Hong Ren , Cunhua Pan , Liang Wang , Zhoubing Kou , Kezhi Wang

Reconfigurable intelligent surface (RIS) has been explored as a supportive technology for wireless communication since around 2019. While the literature highlights the potential of RIS in different modern applications, two key issues have…

Signal Processing · Electrical Eng. & Systems 2025-06-10 Daniel C. Alcantara , Daniel V. C. de Oliveira , Gilderlan T. de Araújo , Paulo R. B. Gomes , André L. F. de Almeida

In interference channels, channel state information (CSI) can be exploited to reduce the interference signal dimensions and thus achieve the optimal capacity scaling, i.e. degrees of freedom, promised by the interference alignment…

Information Theory · Computer Science 2017-01-03 Zhinan Xu , Markus Hofer , Thomas Zemen

Different from conventional passive reconfigurable intelligent surfaces (RISs), incident signals and thermal noise can be amplified at active RISs. By exploiting the amplifying capability of active RISs, noticeable performance improvement…

Information Theory · Computer Science 2025-04-02 Jinho Yang , Hyeongtaek Lee , Junil Choi

The rapid evolution of communication technologies has spurred a growing demand for energy-efficient network architectures and performance metrics. Active Reconfigurable Intelligent Surfaces (RIS) are emerging as a key component in green…

Signal Processing · Electrical Eng. & Systems 2024-11-19 Kai Cao , Tao Yu , Jihong Li , Xiaojing Chen , Yanzan Sun , Qingqing Wu , Wen Chen , Shunqing Zhang

The deployment of multiple reconfigurable intelligent surfaces (RISs) enhances the propagation environment by improving channel quality, but it also complicates channel estimation. Following the conventional wireless communication system…

Information Theory · Computer Science 2024-11-22 Weicong Chen , Yu Han , Chao-Kai Wen , Xiao Li , Shi Jin

Channel state information (CSI) is crucial for massive multi-input multi-output (MIMO) system. As the antenna scale increases, acquiring CSI results in significantly higher system overhead. In this letter, we propose a novel channel…

Signal Processing · Electrical Eng. & Systems 2024-08-14 Lianzheng Shi , Jianhua Zhang , Li Yu , Yuxiang Zhang , Zhen Zhang , Yichen Cai , Guangyi Liu

In intelligent reflecting surface (IRS) assisted communication systems, the acquisition of channel state information (CSI) is a crucial impediment for achieving the beamforming gain of IRS because of the considerable overhead required for…

Information Theory · Computer Science 2020-06-25 Zhaorui Wang , Liang Liu , Shuguang Cui

This paper investigates the downlink channel state information (CSI) sensing in 5G heterogeneous networks composed of user equipments (UEs) with different feedback capabilities. We aim to enhance the CSI accuracy of UEs only affording the…

Information Theory · Computer Science 2024-10-28 Lei Li , Xing Zeng , Ya-Feng Liu , Yanqing Xu , Tsung-Hui Chang

Reconfigurable intelligent surface (RIS) has received widespread attention owing to the superiority of changing the wireless propagation environment intelligently. Channel feedback is essential in frequency division duplex (FDD)…

Information Theory · Computer Science 2020-12-08 Decai Shen , Linglong Dai

A key challenge facing reconfigurable intelligent surfaces (RISs) is channel state information acquisition. Passive RISs cannot generate pilot signals or process data, making rapid temporal changes in the channel problematic. Additionally,…

Signal Processing · Electrical Eng. & Systems 2025-08-15 Amy S. Inwood , Peter J. Smith , Philippa A. Martin , Graeme K. Woodward

In this paper, we investigate a reconfigurable intelligent surface (RIS)-aided multiple-input single-output (MISO) system in the presence of electromagnetic interference (EMI) and channel aging with a Rician fading channel model between the…

Information Theory · Computer Science 2024-05-16 Taoyu Song , Enyu Shi , Yu Lu , Yiyang Zhu , Jiayi Zhang , Bo Ai

Reconfigurable intelligent surfaces (RISs) have emerged as a promising technique to enhance the system spectral efficiency. This paper investigates the ergodic channel capacity (ECC) of an RIS-aided multiple-input multiple-output channel…

Information Theory · Computer Science 2022-08-19 Chongjun Ouyang , Hao Xu , Xujie Zang , Hongwen Yang

Reconfigurable intelligent surface is a potential technology component of future wireless networks due to its capability of shaping the wireless environment. The promising MIMO systems in terms of extended coverage and enhanced capacity…

Information Theory · Computer Science 2022-07-07 Paulo R. B. Gomes , Gilderlan T. de Araújo , Bruno Sokal , André L. F. de Almeida , Behrooz Makki , Gábor Fodor

A reconfigurable intelligent surface (RIS) can shape the radio propagation by passively changing the directions of impinging electromagnetic waves. The optimal control of the RIS requires perfect channel state information (CSI) of all the…

Signal Processing · Electrical Eng. & Systems 2020-02-18 Jiguang He , Markus Leinonen , Henk Wymeersch , Markku Juntti

Optimally extracting the advantages available from reconfigurable intelligent surfaces (RISs) in wireless communications systems requires estimation of the channels to and from the RIS. The process of determining these channels is…

Information Theory · Computer Science 2021-10-04 A. Lee Swindlehurst , Gui Zhou , Rang Liu , Cunhua Pan , Ming Li

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