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Reconfigurable intelligent surfaces (RIS) are expected to play an important role in future wireless communication systems. These surfaces typically rely on their reflection beamforming codebooks to reflect and focus the signal on the target…

Information Theory · Computer Science 2021-10-06 Yu Zhang , Ahmed Alkhateeb

Mutual Coupling (MC) emerges as an inherent feature in Reconfigurable Intelligent Surfaces (RISs), particularly, when they are fabricated with sub-wavelength inter-element spacing. Hence, any physically-consistent model of the RIS operation…

Information Theory · Computer Science 2024-06-11 Dilki Wijekoon , Amine Mezghani , George C. Alexandropoulos , Ekram Hossain

This paper considers a reconfigurable intelligent surface (RIS)-aided millimeter wave (mmWave) downlink communication system where hybrid analog-digital beamforming is employed at the base station (BS). We formulate a power minimization…

Information Theory · Computer Science 2021-01-26 Bei Guo , Renwang Li , Meixia Tao

Intelligent reflecting surface (IRS) is envisioned to play a significant role in future wireless communication systems thanks to its powerful capability of enabling smart and reconfigurable radio environment. In this paper, we study the…

Information Theory · Computer Science 2021-02-23 Weidong Mei , Rui Zhang

This paper presents an asymptotic analysis of Multiple-Input Multiple-Output (MIMO) systems assisted by a 1-bit Reconfigurable Intelligent Surface (RIS) under Ricean fading conditions. Using random matrix theory, we show that, in the…

Signal Processing · Electrical Eng. & Systems 2025-11-12 Panagiotis Gavriilidis , Kyriakos Stylianopoulos , George C. Alexandropoulos

Reconfigurable intelligent surface (RIS) technology has recently emerged as a spectral- and cost-efficient approach for wireless communications systems. However, existing hand-engineered schemes for passive beamforming design and…

Signal Processing · Electrical Eng. & Systems 2021-05-04 Nhan Thanh Nguyen , Ly V. Nguyen , Thien Huynh-The , Duy H. N. Nguyen , A. Lee Swindlehurst , Markku Juntti

Reconfigurable intelligent surfaces (RIS) can reshape the characteristics of wireless channels by intelligently regulating the phase shifts of reflecting elements. Recently, various codebook schemes have been utilized to optimize the…

Information Theory · Computer Science 2025-04-01 Zhiheng Yu , Jiancheng An , Lu Gan , Hongbin Li , Symeon Chatzinotas

Reconfigurable intelligent surface (RIS) has recently emerged as a promising paradigm for future cellular networks. Specifically, due to its capability in reshaping the propagation environment, RIS was introduced to address the blockage…

Signal Processing · Electrical Eng. & Systems 2022-03-28 Peilan Wang , Jun Fang , Weizheng Zhang , Zhi Chen , Hongbin Li , Wei Zhang

Reconfigurable intelligent surfaces (RIS)-assisted massive multiple-input multiple-output (mMIMO) is a promising technology for applications in next-generation networks. However, reflecting-only RIS provides limited coverage compared to a…

Information Theory · Computer Science 2023-09-18 Anastasios Papazafeiropoulos , Le-Nam Tran , Zaid Abdullah , Pandelis Kourtessis , Symeon Chatzinotas

Reconfigurable intelligent surfaces (RISs) have huge potential to improve spectral and energy efficiency in future wireless systems at a minimal cost. However, early prototype results indicate that deploying hundreds or thousands of…

Signal Processing · Electrical Eng. & Systems 2024-12-12 Eduard E. Bahingayi , Nemanja Stefan Perović , Le-Nam Tran

This paper considers a multi-user multiple-input multiple-output (MU-MIMO) system where the downlink communication between a base station (BS) and multiple user equipments (UEs) is aided by a reconfigurable intelligent surface (RIS). We…

Signal Processing · Electrical Eng. & Systems 2024-09-24 Parisa Ramezani , Yasaman Khorsandmanesh , Emil Björnson

Reconfigurable intelligent surface (RIS) constitutes a disruptive technology for enhancing vehicular communication performance through reconfigurable propagation environments. In this paper, we propose an adaptive channel estimation…

Systems and Control · Electrical Eng. & Systems 2026-03-03 Tianyou Li , Haifeng Hu , Dapeng Li

Urban Air Mobility (UAM) relies on developing aerospace industries, where safe aviation and efficient communication are critical features of aircraft. However, it is challenging for aircraft to sustain efficient air-ground communication in…

Computational Engineering, Finance, and Science · Computer Science 2024-09-25 Kai Xiong , Supeng Leng , Liyuan Chen , Dapei Zhang , Chongwen Huang , Chau Yuen

Reconfigurable intelligent surface (RIS) is a novel meta-material which can form a smart radio environment by dynamically altering reflection directions of the impinging electromagnetic waves. In the prior literature, the inter-RIS links…

Information Theory · Computer Science 2024-03-13 Kaizhe Xu , Jiajia Guo , Jun Zhang , Shi Jin , Shaodan Ma

Reconfigurable Intelligent Surface (RIS) has becoming a useful tool in future wireless communication systems for close-distance communication network. This paper we use Reconfigurable Intelligent Surface (RIS) for downlink multi-user…

Information Theory · Computer Science 2021-02-02 RuiTianYi Lu

The advent of Reconfigurable Intelligent Surfaces (RISs) in wireless communication networks unlocks the way to support high frequency radio access (e.g. in millimeter wave) while overcoming their sensitivity to the presence of deep fading…

Information Theory · Computer Science 2022-05-31 Fatima Ezzahra Airod , Mattia Merluzzi , Paolo Di Lorenzo , Emilio Calvanese Strinati

Reconfigurable intelligent surfaces (RISs) have been proposed as a key enabler to improve the coverage of the signals and mitigate the frequent blockages in millimeter wave (mmWave) multiple-input multiple-output (MIMO) communications.…

Signal Processing · Electrical Eng. & Systems 2021-07-16 Rafaela Schroeder , Jiguang He , Glauber Brante , Markku Juntti

Reconfigurable intelligent surface (RIS) is a promising technology for future wireless communication systems. Conventional RIS is constrained to a diagonal scattering matrix, which limits its flexibility. Recently, beyond-diagonal RIS…

Signal Processing · Electrical Eng. & Systems 2026-03-17 Zheyu Wu , Matteo Nerini , Bruno Clerckx

In this paper, we consider a reconfigurable intelligent surface (RIS)-assisted multiple-input multiple-output communication system with multiple antennas at both the base station (BS) and the user. We plan to maximize the achievable rate…

Information Theory · Computer Science 2024-05-28 Yaqiong Zhao , Jindan Xu , Wei Xu , Kezhi Wang , Xinquan Ye , Chau Yuen , Xiaohu You

Reconfigurable intelligent surfaces (RISs) have attracted great attention as a potential beyond 5G technology. These surfaces consist of many passive elements of metamaterials whose impedance can be controllable to change the phase,…

Information Theory · Computer Science 2021-09-09 Özlem Tuğfe Demir , Emil Björnson