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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

Beyond diagonal reconfigurable intelligent surface (BD-RIS) has emerged as an innovative and generalized RIS framework that provides greater flexibility in wave manipulation and enhanced coverage. In comparison to conventional RIS,…

Signal Processing · Electrical Eng. & Systems 2024-10-24 Shreya Khisa , Ali Amhaz , Mohamed Elhattab , Chadi Assi , Sanaa Sharafeddine

Active reconfigurable intelligent surface (RIS) has attracted significant attention as a recently proposed RIS architecture. Owing to its capability to amplify the incident signals, active RIS can mitigate the multiplicative fading effect…

In this letter, we investigate the discrete phase shift design of the intelligent reflecting surface (IRS) in a time division duplexing (TDD) multi-user multiple input multiple output (MIMO) system.We modify the design of deep reinforcement…

Information Theory · Computer Science 2023-07-31 Fengyu Zhao , Wen Chen , Ziwei Liu , Jun Li , Qingqing Wu

For downlink massive multiple-input multiple-output (MIMO) operating in time-division duplex protocol, users can decode the signals effectively by only utilizing the channel statistics as long as channel hardening holds. However, in a…

Information Theory · Computer Science 2022-05-17 Tung T. Vu , Trinh Van Chien , Canh T. Dinh , Hien Quoc Ngo , Michail Matthaiou

Intelligent reflecting surface (IRS) is a promising technology to assist downlink information transmissions from a multi-antenna access point (AP) to a receiver. In this paper, we minimize the AP's transmit power by a joint optimization of…

Signal Processing · Electrical Eng. & Systems 2020-05-26 Jiaye Lin , Yuze Zou , Xiaoru Dong , Shimin Gong , Dinh Thai Hoang , Dusit Niyato

The paper presents a joint beamforming algorithm using statistical channel state information (S-CSI) for reconfigurable intelligent surfaces (RIS) for multiuser MISO wireless communications. We used S-CSI, which is a long-term average of…

Signal Processing · Electrical Eng. & Systems 2022-09-21 Mahdi Eskandari , Huiling Zhu , Arman Shojaeifard , Jiangzhou Wang

This letter proposes a fluid reconfigurable intelligent surface (FRIS) paradigm, extending the conventional reconfigurable intelligent surface (RIS) technology to incorporate position reconfigurability of the elements. In our model, a…

Information Theory · Computer Science 2025-03-20 Han Xiao , Xiaoyan Hu , Kai-Kit Wong , Hanjiang Hong , George C. Alexandropoulos , Chan-Byoung Chae

We study the joint active/passive beamforming and channel blocklength (CBL) allocation in a non-ideal reconfigurable intelligent surface (RIS)-aided ultra-reliable and low-latency communication (URLLC) system. The considered scenario is a…

Information Theory · Computer Science 2024-10-28 Ramin Hashemi , Samad Ali , Nurul Huda Mahmood , Matti Latva-aho

Reconfigurable Intelligent Surface (RIS) has become a popular technology to improve the capability of a THz multiuser Multi-input multi-output (MIMO) communication system. THz wave characteristics, on the other hand, restrict THz beam…

Signal Processing · Electrical Eng. & Systems 2022-07-01 Yicong Liu , Weijie Li , Zihuai Lin

Reconfigurable Intelligent Surfaces (RIS) show great promise in the realm of 6th generation (6G) wireless systems, particularly in the areas of localization and communication. Their cost-effectiveness and energy efficiency enable the…

Signal Processing · Electrical Eng. & Systems 2024-03-12 Han Yan , Hua Chen , Wei Liu , Songjie Yang , Gang Wang , Chau Yuen

We consider a reconfigurable intelligent surface (RIS) assisted multiple-input multiple-output (MIMO) system in the presence of scattering objects. The MIMO transmitter and receiver, the RIS, and the scattering objects are modeled as…

Information Theory · Computer Science 2023-09-19 H. El Hassani , X. Qian , S. Jeong , N. S. Perović , M. Di Renzo , P. Mursia , V. Sciancalepore , X. Costa-Pérez

One of the key enablers of future wireless communications is constituted by massive multiple-input multiple-output (MIMO) systems, which can improve the spectral efficiency by orders of magnitude. However, in existing massive MIMO systems,…

Information Theory · Computer Science 2019-12-10 Linglong Dai , Bichai Wang , Min Wang , Xue Yang , Jingbo Tan , Shuangkaisheng Bi , Shenheng Xu , Fan Yang , Zhi Chen , Marco Di Renzo , Lajos Hanzo

We investigate a multi-user multiple-input multiple-output interference network in the presence of multiple reconfigurable intelligent surfaces (RISs). The entire system is described by using a circuit-based model for the transmitters,…

Information Theory · Computer Science 2021-02-16 Andrea Abrardo , Davide Dardari , Marco Di Renzo , Xuewen Qian

Recently, reconfigurable intelligent surface (RIS), a planar metasurface consisting of a large number of low-cost reflecting elements, has received much attention due to its ability to improve both the spectrum and energy efficiencies by…

Information Theory · Computer Science 2022-03-18 Jiao Wu , Seungnyun Kim , Byonghyo Shim

Reconfigurable intelligent surfaces (RISs) have attracted increasing interest due to their ability to improve the coverage, reliability, and energy efficiency of millimeter wave (mmWave) communication systems. However, designing the RIS…

Signal Processing · Electrical Eng. & Systems 2022-11-15 Shuaifeng Jiang , Ahmed Hindy , Ahmed Alkhateeb

This paper proposes to deploy multiple reconfigurable intelligent surfaces (RISs) in device-to-device (D2D)-underlaid cellular systems. The uplink sum-rate of the system is maximized by jointly optimizing the transmit powers of the users,…

Information Theory · Computer Science 2021-08-24 Yashuai Cao , Tiejun Lv , Wei Ni , Zhipeng Lin

This paper focuses on the fundamental problem of maximizing the achievable weighted sum rate (WSR) at information receivers (IRs) in an intelligent reflecting surface (IRS) assisted simultaneous wireless information and power transfer…

Signal Processing · Electrical Eng. & Systems 2023-03-02 Vaibhav Kumar , Anastasios Papazafeiropoulos , Muhammad Fainan Hanif , Le-Nam Tran , Mark F. Flanagan

We consider a reconfigurable intelligent surface (RIS)-aided massive multi-user multiple-input multiple-output (MIMO) communication system with transceiver hardware impairments (HWIs) and RIS phase noise. Different from the existing…

Information Theory · Computer Science 2021-10-14 Jianxin Dai , Feng Zhu , Cunhua Pan , Hong Ren , Kezhi Wang

Active reconfigurable intelligent surface (RIS) is a new RIS architecture that can reflect and amplify communication signals. It can provide enhanced performance gain compared to the conventional passive RIS systems that can only reflect…

Information Theory · Computer Science 2024-01-12 Qian Zhang , Mingjie Shao , Qiang Li , Ju Liu