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Reconfigurable intelligent surfaces (RIS) can be crucial in next-generation communication systems. However, designing the {RIS} phases according to the instantaneous channel state information (CSI) can be challenging in practice due to the…

Information Theory · Computer Science 2023-09-26 Athira Subhash , Abla Kammoun , Ahmed Elzanaty , Sheetal Kalyani , Yazan H. Al-Badarneh , Mohamed-Slim Alouini

We study the performance of a phase-noise impaired double reconfigurable intelligent surface (RIS)-aided multiuser (MU) multiple-input single-output (MISO) system under spatial correlation at both RISs and base-station (BS). The downlink…

Information Theory · Computer Science 2022-04-19 Zaid Abdullah , Anastasios Papazafeiropoulos , Steven Kisseleff , Symeon Chatzinotas , Bjorn Ottersten

Reconfigurable intelligent surface (RIS) is an emerging technology for wireless communications. In this paper, extensive system level simulations are conducted for analyzing the performance of multi-RIS and multi-base-station (BS)…

Information Theory · Computer Science 2025-02-11 Yifei Yuan , Yuhong Huang , Xin Su , Boyang Duan , Nan Hu , Marco Di Renzo

The reconfigurable intelligent surface (RIS) is one of the promising technologies contributing to the next generation smart radio environment. A novel physics-based RIS channel model is proposed. Particularly, we consider the RIS and the…

Signal Processing · Electrical Eng. & Systems 2020-08-04 Jiaqi Xu , Yuanwei Liu

This works explores the correlation between channels in reconfigurable intelligent surface (RIS)-aided communication systems. In this type of system, an RIS made up of many passive elements with adjustable phases reflects the transmitter's…

Information Theory · Computer Science 2023-05-04 Kuang-Hao , Liu

Reconfigurable intelligent surfaces (RISs) have been proposed as a key enabler to improve the coverage of the signals and mitigate the frequent blockages in millimeter wave (mmWave) multiple-input multiple-output (MIMO) communications.…

Signal Processing · Electrical Eng. & Systems 2021-07-16 Rafaela Schroeder , Jiguang He , Glauber Brante , Markku Juntti

Optimally extracting the advantages available from reconfigurable intelligent surfaces (RISs) in wireless communications systems requires estimation of the channels to and from the RIS. The process of determining these channels is…

Information Theory · Computer Science 2021-10-04 A. Lee Swindlehurst , Gui Zhou , Rang Liu , Cunhua Pan , Ming Li

Channel estimation in reconfigurable intelligent surfaces (RIS)-aided systems is crucial for optimal configuration of the RIS and various downstream tasks such as user localization. In RIS-aided systems, channel estimation involves…

Signal Processing · Electrical Eng. & Systems 2023-12-19 Firas Fredj , Amal Feriani , Amine Mezghani , Ekram Hossain

The incorporation of reconfigurable intelligent surface (RIS) into massive multiple-input-multiple-output (mMIMO) systems can unleash the potential of next-generation networks by improving the performance of user equipments (UEs) in service…

Information Theory · Computer Science 2022-09-12 Anastasios Papazafeiropoulos , Ioannis Krikidis , Pandelis Kourtessis

We propose a reconfigurable intelligent surface (RIS)-assisted underlay spectrum sharing system, in which a RIS-assisted secondary network shares the spectrum licensed for a primary network. The secondary network consists of a secondary…

Information Theory · Computer Science 2024-04-23 Yazan H. Al-Badarneh , Mustafa K. Alshawaqfeh , Osamah S. Badarneh , Yazid M. Khattabi

The reconfigurable intelligent surface (RIS) plays an important role in maintaining the connectivity in millimeter wave (mmWave) MIMO systems when the direct channel between the transceivers is blocked. However, it is difficult to acquire…

Signal Processing · Electrical Eng. & Systems 2021-03-04 Rafaela Schroeder , Jiguang He , Markku Juntti

In this paper, we investigate the two-way communication between two users assisted by a re-configurable intelligent surface (RIS). The scheme that two users communicate simultaneously over Rayleigh fading channels is considered. The…

Signal Processing · Electrical Eng. & Systems 2020-05-05 Saman Atapattu , Rongfei Fan , Prathapasinghe Dharmawansa , Gongpu Wang , Jamie Evans , Theodoros A. Tsiftsis

We analyze the influence of a reconfigurable intelligent surface (RIS) on the Gram channel eigenvalues in a high signal-to-noise ratio (SNR) scenario. This allows to connect specific channel properties with the rank improvement capabilities…

Information Theory · Computer Science 2023-04-17 Dominik Semmler , Michael Joham , Wolfgang Utschick

Channel estimation is challenging for the reconfigurable intelligent surface (RIS)-aided wireless communications. Since the number of coefficients of the cascaded channel among the base station (BS), the RIS and the user equipments (UEs) is…

Signal Processing · Electrical Eng. & Systems 2020-05-19 Chen Hu , Linglong Dai

The reconfigurability of fluid antenna systems (FASs) and reconfigurable intelligent surfaces (RISs) provides significant flexibility in optimizing channel conditions by jointly adjusting the positions of fluid antennas and the phase shifts…

Information Theory · Computer Science 2025-09-29 Xin Zhang , Dongfang Xu , Jingjing Wang , Shenghui Song , Derrick Wing Kwan Ng , Mérouane Debbah

This paper investigates the two-timescale transmission design for reconfigurable intelligent surface (RIS)-aided massive multiple-input multiple-output (MIMO) systems, where the beamforming at the base station (BS) is adapted to the…

Reconfigurable intelligent surfaces (RISs) are considered as potential technologies for the upcoming sixth-generation (6G) wireless communication system. Various benefits brought by deploying one or multiple RISs include increased spectrum…

Signal Processing · Electrical Eng. & Systems 2021-04-16 Jiguang He , Nhan Thanh Nguyen , Rafaela Schroeder , Visa Tapio , Joonas Kokkoniemi , Markku Juntti

A reconfigurable intelligent surface (RIS) is a holographic MIMO surface composed of a large number of passive elements that can induce adjustable phase shifts to the impinging waves. By creating virtual line-of-sight (LOS) paths between…

Signal Processing · Electrical Eng. & Systems 2023-04-06 Mehdi Haghshenas , Parisa Ramezani , Maurizio Magarini , Emil Björnson

A multi-operator wireless communication system is studied where each operator is equipped with a reconfigurable intelligent surface (RIS) to enhance its communication quality. RISs controlled by different operators affect the system…

Information Theory · Computer Science 2025-08-05 Nikolaos I. Miridakis , Panagiotis A. Karkazis

Reconfigurable intelligent surfaces (RISs) have been proposed recently as new technology to tune the wireless propagation channels in real-time. However, most of the current works assume single-RIS (S-RIS)-aided systems, which can be…

Signal Processing · Electrical Eng. & Systems 2021-09-21 Khaled Ardah , Sepideh Gherekhloo , André L. F. de Almeida , Martin Haardt