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Due to the passive nature of Intelligent Reflecting Surface (IRS), channel estimation is a fundamental challenge in IRS-aided wireless networks. Particularly, as the number of IRS reflecting elements and/or that of IRS-served users…

Information Theory · Computer Science 2020-08-04 Xinrong Guan , Qingqing Wu , Rui Zhang

In this paper, we investigate cascaded channel estimation for reconfigurable intelligent surface (RIS)-aided millimeter-wave multi-user communication systems. Since the complex channel gains of the cascaded RIS channel are generally…

Signal Processing · Electrical Eng. & Systems 2025-10-21 Gyoseung Lee , Junil Choi

We consider channel estimation in systems equipped with a reconfigurable intelligent surface (RIS). In order to illuminate the additional cascaded channel as compared to systems without a RIS, commonly an unaffordable amount of pilot…

Signal Processing · Electrical Eng. & Systems 2023-01-27 Benedikt Fesl , Andreas Faika , Nurettin Turan , Michael Joham , Wolfgang Utschick

In this paper, we propose a novel two-stage based uplink channel estimation strategy with reduced pilot overhead and error propagation for a reconfigurable intelligent surface (RIS)-aided multi-user (MU) millimeter wave (mmWave) system.…

Signal Processing · Electrical Eng. & Systems 2022-08-24 Zhendong Peng , Cunhua Pan , Gui Zhou , Hong Ren

Channel estimation is the main hurdle to reaping the benefits promised by the intelligent reflecting surface (IRS), due to its absence of ability to transmit/receive pilot signals as well as the huge number of channel coefficients…

Signal Processing · Electrical Eng. & Systems 2021-06-23 Rui Wang , Liang Liu , Shuowen Zhang , Changyuan Yu

Reconfigurable intelligent surfaces (RISs) are eminently suitable for improving the reliability of wireless communications by jointly designing the active beamforming at the base station (BS) and the passive beamforming at the RIS.…

Information Theory · Computer Science 2025-01-23 Qingchao Li , Mohammed El-Hajjar , Ibrahim Hemadeh , Arman Shojaeifard , Lajos Hanzo

Reconfigurable intelligent surface (RIS) has been recognized as a potential technology for 5G beyond and attracted tremendous research attention. However, channel estimation in RIS-aided system is still a critical challenge due to the…

Information Theory · Computer Science 2021-09-01 Xu Shi , Jintao Wang , Guozhi Chen , Jian Song

Existing works mainly rely on the far-field planar-wave-based channel model to assess the performance of reconfigurable intelligent surface (RIS)-enabled wireless communication systems. However, when the transmitter and receiver are in…

Signal Processing · Electrical Eng. & Systems 2024-03-20 Hao Jiang , Wangqi Shi , Zaichen Zhang , Cunhua Pan , Qingqing Wu , Feng Shu , Ruiqi Liu , Jiangzhou Wang

Beyond diagonal reconfigurable intelligent surface (BD-RIS) refers to a family of RIS architectures characterized by scattering matrices not limited to being diagonal and enables higher wave manipulation flexibility and large performance…

Signal Processing · Electrical Eng. & Systems 2025-04-16 Rui Wang , Shuowen Zhang , Bruno Clerckx , Liang Liu

Reconfigurable intelligent surface (RIS)-aided terahertz (THz)-band communications are promising enablers for future wireless networks. However, array densification at high frequencies introduces significant challenges in accurate channel…

Signal Processing · Electrical Eng. & Systems 2025-05-16 Ahmad Dkhan , Simon Tarboush , Hadi Sarieddeen , Ibrahim Abou-Faycal , Tareq Y. Al-Naffouri

Near-field channel estimation under beam squint effect is critical to future 6G millimeter-wave (mmWave) systems equipped with reconfigurable intelligent surfaces (RIS). In this paper, firstly, we design an extremely large-scale circular…

Signal Processing · Electrical Eng. & Systems 2026-05-07 Wanyuan Cai , Shunli Hong , Youming Li , Menglei Sheng , Mingjun Huang

Reconfigurable Intelligent Surface (RIS) panels are envisioned as a key technology for sixth-generation (6G) wireless networks, providing a cost-effective means to enhance coverage and spectral efficiency. A critical challenge is the…

Signal Processing · Electrical Eng. & Systems 2025-12-16 Saifur Rahman , Syed Luqman Shah , Salman Khan , Jalal Khan , Muhammad Irfan , Maaz Shafi , Said Muhammad , Fazal Muhammad , Mohammad Shahed Akond

The low hardware cost makes ultra-large (XL) reconfigurable intelligent surface (RIS) an attractive solution for the performance enhancement of localization and communication systems, but it results in near-field propagation channels,…

Signal Processing · Electrical Eng. & Systems 2022-12-12 Yijin Pan , Cunhua Pan , Shi Jin , Jiangzhou Wang

Accurate estimation of the cascaded channel from a user equipment (UE) to a base station (BS) via each reconfigurable intelligent surface (RIS) element is critical to realizing the full potential of the RIS's ability to control the overall…

Signal Processing · Electrical Eng. & Systems 2024-11-08 Özlem Tuğfe Demir , Emil Björnson , Luca Sanguinetti

Reconfigurable intelligent surface (RIS) is a candidate technology for future wireless networks. It enables to shape the wireless environment to reach massive connectivity and enhanced data rate. The promising gains of RIS-assisted networks…

Signal Processing · Electrical Eng. & Systems 2022-06-09 Paulo R. B. Gomes , Gilderlan T. de Araújo , Bruno Sokal , André L. F. de Almeida , Behrooz Makki , Gábor Fodor

Reconfigurable intelligent surface (RIS)-empowered communication, has been considered widely as one of the revolutionary technologies for next generation networks. However, due to the novel propagation characteristics of RISs, underlying…

Information Theory · Computer Science 2023-05-16 Jian Sang , Mingyong Zhou , Jifeng Lan , Boning Gao , Wankai Tang , Xiao Li , Shi Jin , Ertugrul Basar , Cen Li , Qiang Cheng , Tie Jun Cui

In this paper, we propose a three-stage unified channel estimation strategy for reconfigurable intelligent surface (RIS)-aided multi-user (MU) multiple-input multiple-output (MIMO) millimeter wave (mmWave) systems with the existence of the…

Signal Processing · Electrical Eng. & Systems 2025-11-25 Taihao Zhang , Zhendong Peng , Cunhua Pan , Hong Ren , Jiangzhou Wang

Reconfigurable intelligent surfaces (RISs) have been proposed recently as new technology to tune the wireless propagation channels in real-time. However, most of the current works assume single-RIS (S-RIS)-aided systems, which can be…

Signal Processing · Electrical Eng. & Systems 2021-09-21 Khaled Ardah , Sepideh Gherekhloo , André L. F. de Almeida , Martin Haardt

The emerging immersive and autonomous services have posed stringent requirements on both communications and localization. By considering the great potential of reconfigurable intelligent surface (RIS), this paper focuses on the joint…

Signal Processing · Electrical Eng. & Systems 2024-03-05 Yunfei Li , Yiting Luo , Xianda Wu , Zheng Shi , Shaodan Ma , Guanghua Yang

In the research of RIS-assisted communication systems, channel estimation is a problem of vital importance for further performance optimization. In order to reduce the pilot overhead to the greatest extent, blind channel estimation methods…

Signal Processing · Electrical Eng. & Systems 2025-08-26 Dianhao Jia , Wenqian Shen , Jianping An , Byonghyo Shim