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Reconfigurable Intelligent Surfaces (RIS) or Intelligent Reflecting Surfaces (IRS) are metasurfaces that can be deployed in various places in wireless environments to make these environments controllable and reconfigurable. In this paper,…

Information Theory · Computer Science 2020-01-22 S. Mohammad Razavizadeh , Tommy Svensson

Reconfigurable intelligent surface (RIS) or intelligent reflecting surface (IRS) has recently been envisioned as one of the most promising technologies in the future sixth-generation (6G) communications. In this paper, we consider the joint…

Information Theory · Computer Science 2021-12-14 Zhangjie Peng , Zhiwei Chen , Cunhua Pan , Gui Zhou , Hong Ren

This work explores the integration of rate-splitting multiple access (RSMA), simultaneous wireless information and power transfer (SWIPT), and beyond-diagonal reconfigurable intelligent surface (BD-RIS) to enhance the spectral-efficiency,…

Signal Processing · Electrical Eng. & Systems 2025-08-12 Muhammad Asif , Zain Ali , Asim Ihsan , Ali Ranjha , Zhu Shoujin , Manzoor Ahmed , Xingwang Li , Symeon Chatzinotas

Reconfigurable Intelligent Surfaces (RISs), comprising large numbers of low-cost and passive metamaterials with tunable reflection properties, have been recently proposed as an enabler for programmable radio propagation environments.…

Information Theory · Computer Science 2021-09-17 Aris L. Moustakas , George C. Alexandropoulos , Mérouane Debbah

In this paper, we survey state-of-the-art research outcomes in the burgeoning field of reconfigurable intelligent surface (RIS) in view of its potential for significant performance enhancement for next generation wireless communication…

Signal Processing · Electrical Eng. & Systems 2020-10-16 Miguel Dajer , Zhengxiang Ma , Leonard Piazzi , Narayan Prasad , Xiao-Feng Qi , Baoling Sheen , Jin Yang , Guosen Yue

Reconfigurable intelligent surface (RIS)-aided near-field communications is investigated. First, the necessity of investigating RIS-aided near-field communications and the advantages brought about by the unique spherical-wave-based…

Information Theory · Computer Science 2024-03-05 Xidong Mu , Jiaqi Xu , Yuanwei Liu , Lajos Hanzo

Wireless communications aided by reconfigurable intelligent surfaces (RISs) is a promising way to improve the coverage for cellular users. The controlled reflection of signals from RISs is especially useful in mm-wave/THz networks when the…

Information Theory · Computer Science 2023-03-14 Vikrant Malik , Gourab Ghatak , Abhishek K. Gupta , Sanket S. Kalamkar

Reconfigurable intelligent surfaces (RISs) are able to provide passive beamforming gain via low-cost reflecting elements and hence improve wireless link quality. This work considers two-way passive beamforming design in RIS-aided frequency…

Information Theory · Computer Science 2021-01-26 Bei Guo , Chenhao Sun , Meixia Tao

Reconfigurable Intelligent Surfaces (RISs), comprising large numbers of low-cost and almost passive metamaterials with tunable reflection properties, have been recently proposed as an enabling technology for programmable wireless…

Information Theory · Computer Science 2022-08-23 Aris L. Moustakas , George C. Alexandropoulos , Mérouane Debbah

In this letter, we derive an expression for the achievable rate in a multiple-input multiple-output (MIMO) system assisted by a beyond-diagonal reconfigurable intelligent surface (BD-RIS) when the channels to and from the BD-RIS are…

Information Theory · Computer Science 2025-04-11 Ignacio Santamaria , Jesus Gutierrez , Mohammad Soleymani , Eduard Jorswieck

This paper presents a theoretical and mathematical framework for the design of a conformal reconfigurable intelligent surface (RIS) that adapts to non-planar geometries, which is a critical advancement for the deployment of RIS on…

Channel estimation is a central bottleneck in BD-RIS-assisted MIMO systems. The richer inter-element coupling that enables large performance gains also makes training and hardware control substantially harder than in diagonal RIS…

Signal Processing · Electrical Eng. & Systems 2026-03-30 Gilderlan Tavares de Araújo , Bruno Sokal , André L. F. de Almeida

Curved reconfigurable intelligent surfaces (RISs) represent a promising frontier for next-generation wireless communication, enabling adaptive wavefront control on nonplanar platforms such as unmanned aerial vehicles and urban…

Signal Processing · Electrical Eng. & Systems 2026-02-02 Filippo Pepe , Ivan Iudice , Giuseppe Castaldi , Marco Di Renzo , Vincenzo Galdi

Although reconfigurable intelligent surfaces (RISs) can improve the performance of wireless networks by smartly reconfiguring the radio environment, existing passive RISs face two key challenges, i.e., double-fading attenuation and…

Signal Processing · Electrical Eng. & Systems 2023-10-05 Wen Wang , Wanli Ni , Hui Tian , Naofal Al-Dhahir

Challenging environments comprise a range of scenarios, which share the fact that it is extremely difficult to establish a communication link using conventional technology due to many impairments typically associated with the propagation…

Signal Processing · Electrical Eng. & Systems 2022-06-23 Steven Kisseleff , Symeon Chatzinotas , Björn Ottersten

This paper focuses on the design of transmission methods and reflection optimization for a wireless system assisted by a single or multiple reconfigurable intelligent surfaces (RISs). The existing techniques are either too complex to…

Information Theory · Computer Science 2023-09-13 Wei Jiang , Hans D. Schotten

The reconfigurable intelligent surface (RIS) technology for metasurfaces is ushering in a new paradigm for wireless communication systems. It provides an accessible way for controlling the interaction between electromagnetic waves with the…

Signal Processing · Electrical Eng. & Systems 2026-01-21 P. H. C. de Souza , M. Khazaee , L. L. Mendes

Recent advancements in 6G systems signal a leap towards universal connectivity and ultra-reliable, low-latency communications for real-time data devices. Yet, these advancements encounter obstacles such as limited device battery life and…

Signal Processing · Electrical Eng. & Systems 2024-03-18 Asad Mahmood , Thang X. Vu , Wali Ullah Khan , Symeon Chatzinotas , Björn Ottersten

Reconfigurable intelligent surface (RIS) is a promising solution to deal with the blockage-sensitivity of millimeter wave band and reduce the high energy consumption caused by network densification. However, deploying large scale RISs may…

Information Theory · Computer Science 2024-02-12 Yining Xu , Sheng Zhou

Orthogonal multi-user multiple-input multiple-output (MU-MIMO) channels allow for optimum performance with simplified precoding/equalization, and they achieve maximum multiplexing gain which is shared fairly among users. Reconfigurable…

Information Theory · Computer Science 2023-05-01 Juan Vidal Alegria , Fredrik Rusek