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In this letter, the channel estimation problem is studied for wireless communication systems assisted by large intelligent surface. Due to features of assistant channel, channel estimation (CE) problem for the investigated system is shown…

Information Theory · Computer Science 2019-11-07 Junliang Lin , Gongpu Wang , Rongfei Fan , Theodoros A. Tsiftsis , Chintha Tellambura

Deep learning-based implicit channel state information (CSI) feedback has been introduced to enhance spectral efficiency in massive MIMO systems. Existing methods often show performance degradation in ultra-low-rate scenarios and…

Signal Processing · Electrical Eng. & Systems 2025-07-17 Zhenyu Liu , Yi Ma , Rahim Tafazolli , Zhi Ding

Intelligent reflecting surface (IRS) has drawn a lot of attention recently as a promising new solution to achieve high spectral and energy efficiency for future wireless networks. By utilizing massive low-cost passive reflecting elements,…

Information Theory · Computer Science 2022-10-17 Ming-Min Zhao , Qingqing Wu , Min-Jian Zhao , Rui Zhang

Intelligent reflecting surface (IRS) can be densely deployed in wireless networks to significantly enhance the communication channels. In this letter, we consider the downlink transmission from a multi-antenna base station (BS) to a…

Information Theory · Computer Science 2022-02-16 Weidong Mei , Rui Zhang

Intelligent reflecting surface (IRS) is a potential candidate for massive multiple-input multiple-output (MIMO) 2.0 technology due to its low cost, ease of deployment, energy efficiency and extended coverage. This chapter investigates the…

Signal Processing · Electrical Eng. & Systems 2026-02-24 Yashuai Cao , Hetong Wang , Tiejun Lv , Wei Ni

Although reconfigurable intelligent surface (RIS) is a promising technology for shaping the propagation environment, it consists of a single-layer structure within inherent limitations regarding the number of beam steering patterns. Based…

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

A reconfigurable intelligent surface (RIS) can shape the radio propagation environment by virtue of changing the impinging electromagnetic waves towards any desired directions, thus, breaking the general Snell's reflection law. However, the…

Signal Processing · Electrical Eng. & Systems 2021-01-15 Jiguang He , Henk Wymeersch , Markku Juntti

This paper provides a theoretical framework for understanding the performance of reconfigurable intelligent surface (RIS)-aided massive multiple-input multiple-output (MIMO) with zero-forcing (ZF) detectors under imperfect channel state…

Information Theory · Computer Science 2021-11-03 Kangda Zhi , Cunhua Pan , Gui Zhou , Hong Ren , Maged Elkashlan , Robert Schober

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

In this letter, we study the beamforming design for channel estimation of multi-functional reconfigurable intelligent surface (MF-RIS)-aided multi-user communications that supports simultaneous signal reflection, refraction, and…

Signal Processing · Electrical Eng. & Systems 2025-01-22 Zaihao Pan , Wen Wang , Gaofeng Nie , Ailing Zheng , Wanli Ni

Non-diagonal reconfigurable intelligent surfaces (RISs) offer enhanced wireless signal manipulation over conventional RIS by enabling the incident signal on any of its $M$ elements to be reflected from another element via an $M \times M$…

Signal Processing · Electrical Eng. & Systems 2025-06-19 Mostafa Samy , Hayder Al-Hraishawi , Abuzar B. M. Adam , Madyan Alsenwi , Symeon Chatzinotas , Björn Otteresten

Reconfigurable Intelligent Surfaces (RISs) are envisioned to play a key role in future wireless communications, enabling programmable radio propagation environments. They are usually considered as almost passive planar structures that…

Information Theory · Computer Science 2022-08-12 Haiyang Zhang , Nir Shlezinger , George C Alexandropoulos , Idban Alamzadeh , Mohammadreza F Imani , Yonina C Eldar

As intelligent reflecting surface (IRS) has emerged as a new and promising technology capable of configuring the wireless environment favorably, channel estimation for IRS-assisted multiple-input multiple-output (MIMO) systems has garnered…

Information Theory · Computer Science 2025-12-22 Zhen Qin , Zhihui Zhu

This paper proposes a scalable channel estimation and reflection optimization framework for reconfigurable intelligent surface (RIS)-enhanced orthogonal frequency division multiplexing (OFDM) systems. Specifically, the proposed scheme…

Information Theory · Computer Science 2021-10-26 Jiancheng An , Qingqing Wu , Chau Yuen

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

Compared to traditional intelligent reflecting surfaces(IRS), aerial IRS (AIRS) has unique advantages, such as more flexible deployment and wider service coverage. However, modeling AIRS in the channel presents new challenges due to their…

Information Theory · Computer Science 2023-09-06 Shaoyi Liu , Nan Ma , Yaning Chen , Ke Peng , Dongsheng Xue

In frequency division duplex (FDD) massive MIMO systems, reliable downlink channel estimation is essential for the subsequent data transmission but is realized at the cost of massive pilot overhead due to hundreds of antennas at base…

Signal Processing · Electrical Eng. & Systems 2022-11-01 An Chen , Wenbo Xu , Liyang Lu , Yue Wang

The recently completed 5G new radio standard is a result of several cutting-edge technologies, including massive multiple-input multiple-output (MIMO), millimeter (mm)-Wave communication and network densification. However, these…

Signal Processing · Electrical Eng. & Systems 2019-12-16 Qurrat-Ul-Ain Nadeem , Abla Kammoun , Anas Chaaban , Merouane Debbah , Mohamed-Slim Alouini

We study downlink channel estimation in a multi-cell Massive multiple-input multiple-output (MIMO) system operating in time-division duplex. The users must know their effective channel gains to decode their received downlink data. Previous…

Information Theory · Computer Science 2021-11-30 Amin Ghazanfari , Trinh Van Chien , Emil Björnson , Erik G. Larsson