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Channel estimation in reconfigurable intelligent surface (RIS) assisted multiple input multiple output (MIMO) communication systems is challenging as pilots cannot be decoded at or transmitted from a RIS with only passive elements. We…

Signal Processing · Electrical Eng. & Systems 2021-03-22 Battu Deepak , R. S. Prasobh Sankar , Sundeep Prabhakar Chepuri

Due to their ability to create favorable line-of-sight (LoS) propagation environments, intelligent reflecting surfaces (IRSs) are regarded as promising enablers for future millimeter-wave (mm-wave) wireless communication. In this paper, we…

Information Theory · Computer Science 2021-07-27 Tian Lin , Xianghao Yu , Yu Zhu , Robert Schober

In this paper, we investigate a cascaded channel estimation method for a millimeter wave (mmWave) massive multiple-input multiple-output (MIMO) system aided by a reconfigurable intelligent surface (RIS) with the BS equipped with…

Information Theory · Computer Science 2024-01-17 Ruizhe Wang , Hong Ren , Cunhua Pan , Shi Jin , Petar Popovski , Jiangzhou Wang

Reconfigurable intelligent surfaces (RISs) consist of many passive elements of metamaterials whose impedance can be controllable to change the characteristics of wireless signals impinging on them. Channel estimation is a critical task when…

Information Theory · Computer Science 2023-09-14 Özlem Tuğfe Demir , Emil Björnson

We consider the problem of channel estimation and joint active and passive beamforming for reconfigurable intelligent surface (RIS) assisted millimeter wave (mmWave) multiple-input multiple-output (MIMO) orthogonal frequency division…

Signal Processing · Electrical Eng. & Systems 2022-10-05 Xi Zheng , Jun Fang , Hongwei Wang , Peilan Wang , Hongbin Li

A significant increase in the number of reconfigurable intelligent surface (RIS) elements results in a spherical wavefront in the near field of extremely large-scale RIS (XL-RIS). Although the channel matrix of the cascaded two-hop link may…

Signal Processing · Electrical Eng. & Systems 2023-11-14 Zixing Tang , Yuanbin Chen , Ying Wang , Tianqi Mao , Qingqing Wu , Marco Di Renzo , Lajos Hanzo

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

Reconfigurable Intelligent Surface (RIS) is considered as an energy-efficient solution for future wireless communication networks due to its fast and low-cost configuration. In this letter, we consider the estimation of cascaded channels in…

Signal Processing · Electrical Eng. & Systems 2022-10-25 Mengbing Liu , Xin Li , Boyu Ning , Chongwen Huang , Sumei Sun , Chau Yuen

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

A reconfigurable intelligent surface (RIS) consists of massive meta elements, which can improve the performance of future wireless communication systems. Existing RIS-aided channel estimation methods try to estimate the cascaded channel…

Information Theory · Computer Science 2021-08-20 Wei Zhang , Wee Peng Tay

Reconfigurable intelligent surfaces (RISs) have been introduced as a remedy for mitigating frequent blockages in millimeter wave (mmWave) multiple-input multiple-output (MIMO) communication networks. However, perfect or nearly perfect…

Signal Processing · Electrical Eng. & Systems 2021-06-22 Rafaela Schroeder , Jiguang He , Markku Juntti

In this paper, we study the high-resolution channel estimation problem for intelligent reflecting surface (IRS)-assisted millimeter wave (mmWave) multiple-input-multiple-output (MIMO) communications, which is a prerequisite to guarantee…

Signal Processing · Electrical Eng. & Systems 2020-06-23 C. Jia , J. Cheng , H. Gao , W. Xu

Next-generation wireless technologies such as 6G aim to meet demanding requirements such as ultra-high data rates, low latency, and enhanced connectivity. Extremely Large-Scale MIMO (XL-MIMO) and Reconfigurable Intelligent Surface (RIS) are…

Information Theory · Computer Science 2026-01-01 Muhammad Kamran Saeed , Ashfaq Khokhar , Shakil Ahmed

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

Channel estimation is one of the key challenges for the deployment of extremely large-scale reconfigurable intelligent surface (XL-RIS) assisted multiple-input multiple-output (MIMO) systems. In this paper, we study the channel estimation…

Signal Processing · Electrical Eng. & Systems 2024-04-29 Jeongjae Lee , Hyeongjin Chung , Yunseong Cho , Sunwoo Kim , Songnam Hong

Reconfigurable Intelligent Surfaces (RISs) have been recently considered as an energy-efficient solution for future wireless networks. Their dynamic and low-power configuration enables coverage extension, massive connectivity, and…

Information Theory · Computer Science 2020-11-30 Li Wei , Chongwen Huang , George C. Alexandropoulos , Zhaohui Yang , Chau Yuen , Zhaoyang Zhang

In Reconfigurable intelligent surface (RIS)-assisted systems the acquisition of CSI and the optimization of the reflecting coefficients constitute a pair of salient design issues. In this paper, a novel channel training protocol is…

Information Theory · Computer Science 2021-06-01 Jiancheng An , Chao Xu , Li Wang , Yusha Liu , Lu Gan , Lajos Hanzo

The accurate estimation of Channel State Information (CSI) is of crucial importance for the successful operation of Multiple-Input Multiple-Output (MIMO) communication systems, especially in a Multi-User (MU) time-varying environment and…

Information Theory · Computer Science 2022-02-22 Jide Yuan , George C. Alexandropoulos , Eleftherios Kofidis , Tobias Lindstrm Jensen , Elisabeth De Carvalho

To reap the benefits of reconfigurable intelligent surfaces (RIS), channel state information (CSI) is generally required. However, CSI acquisition in RIS systems is challenging and often results in very large pilot overhead, especially in…

Signal Processing · Electrical Eng. & Systems 2023-09-21 Ly V. Nguyen , A. Lee Swindlehurst

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