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Prior works on near-field beam training have mostly assumed dedicated polar-domain codebook and on-grid range estimation, which, however, may suffer long training overhead and degraded estimation accuracy. To address these issues, we…

Information Theory · Computer Science 2024-05-08 Xun Wu , Changsheng You , Jiapeng Li , Yunpu Zhang

In this paper, we study efficient multi-beam training design for near-field communications to reduce the beam training overhead of conventional single-beam training methods. In particular, the array-division based multi-beam training…

Signal Processing · Electrical Eng. & Systems 2024-06-24 Cong Zhou , Changsheng You , Zixuan Huang , Shuo Shi , Yi Gong , Chan-Byoung Chae , Kaibin Huang

Reconfigurable intelligent surface (RIS) is a two-dimensional periodic structure integrated with a large number of reflective elements, which can manipulate electromagnetic waves in a digital way, offering great potentials for wireless…

Machine Learning · Computer Science 2025-01-22 Zhen Zhang , Jun Hui Qiu , Jun Wei Zhang , Hui Dong Li , Dong Tang , Qiang Cheng , Wei Lin

Millimeter wave (mmWave) communications are vulnerable to blockages and node mobility due to the highly directional signal beams. The emerging Reconfigurable Intelligent Surfaces (RISs) technique can effectively mitigate the blockage…

Signal Processing · Electrical Eng. & Systems 2024-10-28 Xiaowen Tian , Zhi Sun

The adoption of a Reconfigurable Intelligent Surface (RIS) for downlink multi-user communication from a multi-antenna base station is investigated in this paper. We develop energy-efficient designs for both the transmit power allocation and…

Information Theory · Computer Science 2022-06-23 Chongwen Huang , Alessio Zappone , George C. Alexandropoulos , Mérouane Debbah , Chau Yuen

A communication link aided by a reconfigurable intelligent surface (RIS) is studied in which the transmitter can control the state of the RIS via a finite-rate control link. Channel state information (CSI) is acquired at the receiver based…

Information Theory · Computer Science 2020-12-02 Roy Karasik , Osvaldo Simeone , Marco Di Renzo , Shlomo Shamai

The sixth-generation (6G) wireless technology recognizes the potential of reconfigurable intelligent surfaces (RIS) as an effective technique for intelligently manipulating channel paths through reflection to serve desired users.…

Information Theory · Computer Science 2023-11-21 Li-Hsiang Shen , Chia-Jou Ku , Kai-Ten Feng

Reconfigurable Intelligent Surfaces (RISs) are an emerging technology for future wireless communication systems, enabling improved coverage in an energy efficient manner. RISs are usually metasurfaces, constituting of two-dimensional…

Information Theory · Computer Science 2022-03-28 Konstantinos D. Katsanos , Nir Shlezinger , Mohammadreza F. Imani , George C. Alexandropoulos

Reconfigurable intelligent surfaces (RISs) represent a promising candidate for sixth-generation (6G) wireless networks, as the RIS technology provides a new solution to control the propagation channel in order to improve the efficiency of a…

Information Theory · Computer Science 2022-08-15 Mohamad H. Dinan , Nemanja Stefan Perovic , Mark F. Flanagan

The channel estimation overhead of reconfigurable intelligent surface (RIS) assisted communication systems can be prohibitive. Prior works have demonstrated via simulations that grouping neighbouring RIS elements can help to reduce the…

Information Theory · Computer Science 2021-11-23 Neel Kanth Kundu , Zan Li , Junhui Rao , Shanpu Shen , Matthew R. McKay , Ross Murch

The reconfigurable intelligent surface (RIS) technology is a potential solution to enhance network capacity and coverage without significant investment in additional infrastructure in 6G networks. This work highlights the interest of the…

Reconfigurable intelligent surface (RIS) is an emerging technology to enhance wireless communication in terms of energy cost and system performance by equipping a considerable quantity of nearly passive reflecting elements. This study…

Information Theory · Computer Science 2021-03-17 Jun Zhang , Jie Liu , Shaodan Ma , Chao-Kai Wen , Shi Jin

The demanding objectives for the future sixth generation (6G) of wireless communication networks have spurred recent research efforts on novel materials and radio-frequency front-end architectures for wireless connectivity, as well as…

Information Theory · Computer Science 2022-03-08 Mengnan Jian , George C. Alexandropoulos , Ertugrul Basar , Chongwen Huang , Ruiqi Liu , Yuanwei Liu , Chau Yuen

Reconfigurable intelligent surface (RIS) has become a promising technology to realize the programmable wireless environment via steering the incident signal in fully customizable ways. However, a major challenge in RIS-aided communication…

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

Enabling multi-target sensing in near-field integrated sensing and communication (ISAC) systems is a key challenge, particularly when line-of-sight paths are blocked. This paper proposes a beamforming framework that leverages a…

Signal Processing · Electrical Eng. & Systems 2025-09-11 Hang Ruan , Homa Nikbakht , Ruizhi Zhang , Honglei Chen , Yonina C. Eldar

The concept of the frequency diverse reconfigurable intelligent surface (FD-RIS) technology has been introduced, which can enable simultaneous implementation of distance-angle beamforming in far-field communication scenarios. In order to…

Information Theory · Computer Science 2025-12-02 Han Xiao , Xiaoyan Hu , Wenjie Wang , Kai-Kit Wong , Kun Yang , Shi Jin

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

Reconfigurable Intelligent Surfaces (RIS) are considered a key enabler to achieve the vision of Smart Radio Environments, where the propagation environment can be programmed and controlled to enhance the efficiency of wireless systems.…

Networking and Internet Architecture · Computer Science 2023-01-24 Charbel Bou Chaaya , Mohamad Assaad , Tijani Chahed

Fluid reconfigurable intelligent surfaces (FRIS) extend conventional reconfigurable intelligent surfaces (RIS) by adding spatial reconfigurability through switchable apertures, pattern-reconfigurable units, fluidic conductive materials, or…

Information Theory · Computer Science 2026-05-22 Xusheng Zhu , Kai-Kit Wong , Sai Xu , Hao Xu , Wen Chen , Hyundong Shin