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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

The massive number of antennas in extremely large aperture array (ELAA) systems shifts the propagation regime of signals in internet of things (IoT) communication systems towards near-field spherical wave propagation. We propose a…

Signal Processing · Electrical Eng. & Systems 2025-04-18 Quan Zhou , Jingjing Zhao , Kaiquan Cai , Yanbo Zhu

Reconfigurable intelligent surface (RIS)-assisted communication appears as one of the potential enablers for sixth generation (6G) wireless networks by providing a new degree of freedom in the system design to telecom operators.…

Signal Processing · Electrical Eng. & Systems 2021-09-21 E. Basar , I. Yildirim , F. Kilinc

Downlink reconfigurable intelligent surface (RIS)-assisted multi-input-multi-output (MIMO) systems are considered with far-field, near-field, and hybrid-far-near-field channels. According to the angular or distance information contained in…

Information Theory · Computer Science 2023-10-03 Suyu Lv , Yuanwei Liu , Xiaodong Xu , Arumugam Nallanathan , A. Lee Swindlehurst

Reconfigurable intelligent surfaces, with their large number of antennas, offer an interesting opportunity for high spatial-resolution imaging. In this paper, we propose a novel RIS-aided integrated imaging and communication system that can…

Signal Processing · Electrical Eng. & Systems 2024-01-30 Hao Luo , Ahmed Alkhateeb

Reconfigurable intelligent surface (RIS) assisted millimeter-wave (mmWave) communication systems relying on hybrid beamforming structures are capable of achieving high spectral efficiency at a low hardware complexity and low power…

Signal Processing · Electrical Eng. & Systems 2022-01-13 Chenghao Feng , Wenqian Shen , Jianping An , Lajos Hanzo

Millimeter wave (MmWave) systems are vulnerable to blockages, which cause signal drop and link outage. One solution is to deploy reconfigurable intelligent surfaces (RISs) to add a strong non-line-of-sight path from the transmitter to…

Signal Processing · Electrical Eng. & Systems 2022-06-01 Xiaowen Tian , Nuria Gonzalez-Prelcic , Robert W. Heath

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

The concept of reconfigurable intelligent surface (RIS) has been proposed to change the propagation of electromagnetic waves, e.g., reflection, diffraction, and refraction. To accomplish this goal, the phase values of the discrete RIS units…

Signal Processing · Electrical Eng. & Systems 2019-11-11 Jiguang He , Henk Wymeersch , Tachporn Sanguanpuak , Olli Silvén , Markku Juntti

Reconfigurable intelligent surface (RIS) is considered as one of the key technologies for future 6G communications. To fully unleash the performance of RIS, accurate channel state information (CSI) is crucial. Beam training is widely…

Information Theory · Computer Science 2025-01-24 Yuhao Chen , Linglong Dai

Reconfigurable intelligent surfaces (RISs) enable reliable low-latency millimeter wave (mmWave) communication links in cases of a blocked line-of-sight (LoS) between the base station (BS) and the user equipment (UE), i.e. a RIS mounted on a…

Systems and Control · Electrical Eng. & Systems 2024-02-13 Hamed Radpour , Markus Hofer , David Loschenbrand , Lukas Walter Mayer , Andreas Hofmann , Martin Schiefer , Thomas Zemen

Continuous efforts have been devoted to integrate millimeter wave (mmWave) and terahertz (THz) bands into future communication standards in order to overcome the bandwidth shortage problem and achieve high data rates, primarily through…

Signal Processing · Electrical Eng. & Systems 2026-03-05 Sung Hyuck Hong , Junil Choi

A beyond-diagonal reconfigurable intelligent surface (BD-RIS) is an innovative type of reconfigurable intelligent surface (RIS) that has recently been proposed and is considered a revolutionary advancement in wave manipulation. Unlike the…

Social and Information Networks · Computer Science 2026-01-05 Abd Ullah Khan , Uman Khalid , Trung Q. Duong , Hyundong Shin

A conceptual example is first analyzed to show that efficient wireless communications is possible, when user equipment (UE) receiver, BS transmitter or/and the scatter (reflector) in wireless channels employ the required channel state…

Signal Processing · Electrical Eng. & Systems 2024-03-19 Lie-Liang Yang

Unmanned aerial vehicles (UAVs) have brought a lot of flexibility in the network deployment. However, UAVs suffer from the high mobility and instability. To improve the capacity and reliability of the UAV networks, millimeter-wave (mmWave)…

Information Theory · Computer Science 2021-08-09 Lisi Jiang , Hamid Jafarkhani

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

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

A fundamental challenge for millimeter wave (mmWave) communications lies in its sensitivity to the presence of blockages, which impact the connectivity of the communication links and ultimately the reliability of the entire network. In this…

Signal Processing · Electrical Eng. & Systems 2021-01-05 Gui Zhou , Cunhua Pan , Hong Ren , Kezhi Wang , Maged Elkashlan , Marco Di Renzo

Terahertz (THz) systems have the benefit of high bandwidth and hence are capable of supporting ultra-high data rates, albeit at the cost of high pathloss. Hence they tend to harness high-gain beamforming. Therefore a novel hybrid 3D…

Signal Processing · Electrical Eng. & Systems 2022-02-07 Xufang Wang , Zihuai Lin , Feng Lin , Lajos Hanzo , Life Fellow

Recently there has been a flurry of research on the use of reconfigurable intelligent surfaces (RIS) in wireless networks to create smart radio environments. In a smart radio environment, surfaces are capable of manipulating the propagation…

Signal Processing · Electrical Eng. & Systems 2020-05-05 Mohamed A. ElMossallamy , Hongliang Zhang , Lingyang Song , Karim G. Seddik , Zhu Han , Geoffrey Ye Li