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Reconfigurable intelligent surfaces (RIS) have been actively researched as a potential technique for future wireless communications, which intelligently ameliorate the signal propagation environment. In the conventional design, each RIS…

Information Theory · Computer Science 2022-03-17 Qingchao Li , Mohammed El-Hajjar , Ibrahim Hemadeh , Arman Shojaeifard , Alain A. M. Mourad , Bruno Clerckx , Lajos Hanzo

Reconfigurable intelligent surface (RIS) is a promising candidate technology of the upcoming Sixth Generation (6G) communication system for its ability to provide unprecedented spectral and energy efficiency increment through passive…

Information Theory · Computer Science 2023-09-29 Haochen Li , Zhiwen Pan , Bin Wang , Nan Liu , Xiaohu You

Reconfigurable intelligent surfaces (RIS) as an effective technique for intelligently manipulating channel paths through reflection to serve desired users. Full-duplex (FD) systems, enabling simultaneous transmission and reception from a…

Information Theory · Computer Science 2023-11-08 Li-Hsiang Shen , Chia-Jou Ku , Kai-Ten Feng

In reconfigurable intelligent surface (RIS)-assisted systems, the optimization of the phase shifts requires separate acquisition of the channel state information (CSI) for the direct and RIS-assisted channels, posing significant design…

Information Theory · Computer Science 2022-03-30 Kevin Weinberger , Aydin Sezgin

The deployment of multiple reconfigurable intelligent surfaces (RISs) enhances the propagation environment by improving channel quality, but it also complicates channel estimation. Following the conventional wireless communication system…

Information Theory · Computer Science 2024-11-22 Weicong Chen , Yu Han , Chao-Kai Wen , Xiao Li , Shi Jin

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

In this paper, we consider a reconfigurable intelligent surface (RIS)-assisted multiple-input multiple-output communication system with multiple antennas at both the base station (BS) and the user. We plan to maximize the achievable rate…

Information Theory · Computer Science 2024-05-28 Yaqiong Zhao , Jindan Xu , Wei Xu , Kezhi Wang , Xinquan Ye , Chau Yuen , Xiaohu You

Cell-Free Massive multiple-input multiple-output (MIMO) and reconfigurable intelligent surface (RIS) are two promising technologies for application to beyond-5G networks. This paper considers Cell-Free Massive MIMO systems with the…

Information Theory · Computer Science 2021-12-20 Trinh Van Chien , Hien Quoc Ngo , Symeon Chatzinotas , Marco Di Renzo , Björn Ottersten

Reconfigurable intelligent surfaces (RISs) and fluid antennas (FAs) are key technologies for enhancing spatial degrees of freedom in future wireless networks. However, channel acquisition in RIS-aided FA systems is challenging as cascaded…

Signal Processing · Electrical Eng. & Systems 2026-04-21 Josué V. de Araújo , Gilderlan T. de Araújo , André L. F. de Almeida

Reconfigurable intelligent surface (RIS) is envisioned as a promising technology for next-generation wireless communications. Its deployment introduces a RIS cascade link between the transmitter (Tx) and receiver (Rx), which makes its…

Signal Processing · Electrical Eng. & Systems 2023-03-28 Huiwen Gong , Jianhua Zhang , Yuxiang Zhang , Zhengfu Zhou , Guangyi Liu

We propose a holographic version of a reconfigurable intelligent surface (RIS) and investigate its application to terahertz (THz) massive multiple-input multiple-output systems. Capitalizing on the miniaturization of THz electronic…

Information Theory · Computer Science 2021-03-22 Ziwei Wan , Zhen Gao , Feifei Gao , Marco Di Renzo , Mohamed-Slim Alouini

Next-generation wireless technologies such as 6G aim to meet demanding requirements such as ultra-high data rates, low latency, and enhanced connectivity. Extremely Large-Scale MIMO (XL-MIMO) and Reconfigurable Intelligent Surface (RIS) are…

Information Theory · Computer Science 2026-01-01 Muhammad Kamran Saeed , Ashfaq Khokhar , Shakil Ahmed

Reconfigurable intelligent surface (RIS) provides a promising way to build the programmable wireless transmission environments in the future. Owing to the large number of reflecting elements used at the RIS, joint optimization for the…

Information Theory · Computer Science 2021-01-11 Xiaoyan Ma , Shuaishuai Guo , Haixia Zhang , Yuguang Fang , Dongfeng Yuan

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 chapter focuses on a hardware architecture for semi-passive Reconfigurable Intelligent Surfaces (RISs) and investigates its consideration for boosting the performance of Multiple-Input Multiple-Output (MIMO) communication systems. The…

Signal Processing · Electrical Eng. & Systems 2025-06-19 George C. Alexandropoulos , Konstantinos D. Katsanos , Evangelos Vlachos

The reconfigurable intelligent surface (RIS) is a promising technology for next-generation wireless communication. It comprises many passive antennas, which reflect signals from the transmitter to the receiver with adjusted phases without…

Signal Processing · Electrical Eng. & Systems 2023-01-18 Bile Peng , Finn Siegismund-Poschmann , Eduard A. Jorswieck

We consider the problem of channel estimation in a multiple-input-multiple-output (MIMO) full-duplex (FD) wireless communication system assisted by a reconfigurable intelligent surface (RIS) with hardware impairments (HI) occurring at the…

Signal Processing · Electrical Eng. & Systems 2023-07-25 Alexander James Fernandes , Ioannis Psaromiligkos

This work proposes RIS-enabled channel signature modulation (RIS-CSM), a lightweight index modulation scheme for reconfigurable intelligent surfaces (RIS). An N-element RIS is partitioned into disjoint groups, each employing predetermined…

Information Theory · Computer Science 2025-10-17 M. A. Teeti

Beyond diagonal reconfigurable intelligent surface (BD-RIS) is a new advance and generalization of the RIS technique. BD-RIS breaks through the isolation between RIS elements by creatively introducing inter-element connections, thereby…

Signal Processing · Electrical Eng. & Systems 2024-06-11 Hongyu Li , Shanpu Shen , Yumeng Zhang , Bruno Clerckx

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