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Reconfigurable intelligent surface (RIS) has emerged as a cost-effective and promising solution to extend the wireless signal coverage and improve the performance via passive signal reflection. Different from existing works which do not…

Information Theory · Computer Science 2023-11-22 Anastasios Papazafeiropoulos , Ahmet M. Elbir , Pandelis Kourtessis , Ioannis Krikidis , Symeon Chatzinotas

Reconfigurable intelligent surface (RIS) has emerged as a cost-effective solution for green communications in 6G. However, its further extensive use has been greatly limited due to its fully passive characteristics. Considering the…

Information Theory · Computer Science 2025-01-15 Jintao Wang , Chengzhi Ma , Shiqi Gong , Xi Yang , Shaodan Ma

Reconfigurable intelligent surface (RIS) can be employed in a cell-free system to create favorable propagation conditions from base stations (BSs) to users via configurable elements. However, prior works on RIS-aided cell-free system…

Information Theory · Computer Science 2022-08-15 Xu Gan , Caijun Zhong , Chongwen Huang , Zhaohui Yang , Zhaoyang Zhang

This work studies the problems of channel estimation and beamforming for active reconfigurable intelligent surface (RIS)-assisted multiple-input multiple-output (MIMO) communication, incorporating the mutual coupling (MC) effect through an…

Signal Processing · Electrical Eng. & Systems 2025-07-31 Pinjun Zheng , Simon Tarboush , Hadi Sarieddeen , Tareq Y. Al-Naffouri

Millimeter wave (mmWave) full-duplex (FD) is a promising technique for improving capacity by maximizing the utilization of both time and the rich mmWave frequency resources. Still, it has restrictions due to FD self-interference (SI) and…

Information Theory · Computer Science 2023-03-28 Songjie Yang , Wanting Lyu , Yunis Xanthos , Zhongpei Zhang , Chadi Assi , Chau Yuen

Active reconfigurable intelligent surfaces (RISs) have recently been proposed to compensate for the severe multiplicative fading effect of conventional passive RIS-aided systems. Each reflecting element of active RISs is assisted by an…

Information Theory · Computer Science 2023-02-21 Gui Zhou , Cunhua Pan , Hong Ren , Dongfang Xu , Zaichen Zhang , Jiangzhou Wang , Robert Schober

Benefiting from the growth of the bandwidth, Terahertz (THz) communication can support the new application with explosive requirements of the ultra-high-speed rates for future 6G wireless systems. In order to compensate for the path loss of…

Information Theory · Computer Science 2021-12-16 Yu Lu , Mo Hao , Richard MAcKenzie

We consider a multi-user multiple-input single-output (MISO) communications system which is assisted by a hybrid active-passive reconfigurable intelligent surface (RIS). Unlike conventional passive RISs, hybrid RIS is equipped with a few…

Information Theory · Computer Science 2022-03-22 Nhan Thanh Nguyen , Van-Dinh Nguyen , Qingqing Wu , Antti Tolli , Symeon Chatzinotas , Markku Juntti

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

Integrated positioning and communication (IPAC) system and reconfigurable intelligent surface (RIS) are both considered to be key technologies for future wireless networks. Therefore, in this paper, we propose a RIS-enabled IPAC scheme with…

Signal Processing · Electrical Eng. & Systems 2023-10-26 Junchang Sun , Shuai Ma , Shiyin Li

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

In this paper, we use a reconfigurable intelligent surface (RIS) to enhance the radar sensing and communication capabilities of a mmWave dual function radar communication system. To simultaneously localize the target and to serve the user,…

Signal Processing · Electrical Eng. & Systems 2021-05-06 R. S. Prasobh Sankar , Battu Deepak , Sundeep Prabhakar Chepuri

A reconfigurable intelligent surface (RIS) is a nearly-passive flat layer made of inexpensive elements that can add a tunable phase shift to the impinging electromagnetic wave and are controlled by a low-power electronic circuit. This paper…

Signal Processing · Electrical Eng. & Systems 2022-05-04 Stefano Buzzi , Emanuele Grossi , Marco Lops , Luca Venturino

Reconfigurable intelligent surfaces (RISs) will play a key role to establish reliable low-latency millimeter wave (mmWave) communication links for indoor automation and control applications. In case of a blocked line-of-sight between the…

Systems and Control · Electrical Eng. & Systems 2023-08-23 Hamed Radpour , Markus Hofer , Lukas Walter Mayer , Andreas Hofmann , Martin Schiefer , Thomas Zemen

In this paper, we propose a dynamic hybrid active-passive reconfigurable intelligent surface (HRIS) to enhance multiple-input-single-output (MISO) communications, leveraging the property of dynamically placing active elements. Specifically,…

Information Theory · Computer Science 2024-10-10 Jintao Wang , Binggui Zhou , Chengzhi Ma , Shiqi Gong , Guanghua Yang , Shaodan Ma

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

Millimeter-wave (mmWave) positioning has emerged as a promising technology for next-generation intelligent systems. The advent of reconfigurable intelligent surfaces (RISs) has revolutionized high-precision mmWave localization by enabling…

Signal Processing · Electrical Eng. & Systems 2026-04-23 Xin Cheng , Yuqing Yang , Guangjie Han , Menglu Li , Ruoguang Li , Feng Shu

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

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

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