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This letter investigates the reconfigurable intelligent surface (RIS)-aided massive multiple-input multiple-output (MIMO) systems with a two-timescale design. First, the zero-forcing (ZF) detector is applied at the base station (BS) based…

Information Theory · Computer Science 2021-11-18 Kangda Zhi , Cunhua Pan , Hong Ren , Kezhi Wang

Reconfigurable intelligent surface (RIS) is regarded as a promising technology with great potential to boost wireless networks. Affected by the "double fading" effect, however, conventional passive RIS cannot bring considerable performance…

Signal Processing · Electrical Eng. & Systems 2022-10-06 Qi Zhu , Ming Li , Rang Liu , Yang Liu , Qian Liu

Reconfigurable intelligent surfaces (RISs) have been introduced as a remedy for mitigating frequent blockages in millimeter wave (mmWave) multiple-input multiple-output (MIMO) communication networks. However, perfect or nearly perfect…

Signal Processing · Electrical Eng. & Systems 2021-06-22 Rafaela Schroeder , Jiguang He , Markku Juntti

We investigate a reconfigurable intelligent surface (RIS)-aided multi-user massive multiple-input multi-output (MIMO) system where low-resolution digital-analog converters (DACs) are configured at the base station (BS) in order to reduce…

Information Theory · Computer Science 2021-08-24 Jianxin Dai , Yuanyuan Wang , Cunhua Pan , Kangda Zhi , Hong Ren , Kezhi Wang

This paper investigates the performance of a two-timescale transmission design for uplink reconfigurable intelligent surface (RIS)-aided cell-free massive multiple-input multiple-output (CF-mMIMO) systems. We consider the Rician channel…

Signal Processing · Electrical Eng. & Systems 2023-08-07 Jianxin Dai , Jin Ge , Kangda Zhi , Cunhua Pan , Zaichen Zhang , Jiangzhou Wang , Xiaohu You

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

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 surfaces (RIS)-assisted cell-free massive multiple-input multiple-output (CF mMIMO) systems have emerged as a promising technology for sixth-generation communication systems. These systems capitalize on RIS to…

Signal Processing · Electrical Eng. & Systems 2024-12-24 Yu Lu , Jiayi Zhang , Enyu Shi , Peng Zhang , Derrick Wing Kwan Ng , Dusit Niyato , Bo Ai

In opportunistic cognitive radio networks, when the primary signal is very weak compared to the background noise, the secondary user requires long sensing time to achieve a reliable spectrum sensing performance, leading to little remaining…

Information Theory · Computer Science 2024-04-29 Jungang Ge , Ying-Chang Liang , Sumei Sun , Yonghong Zeng , Zhidong Bai

Simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS)-aided cell-free massive multiple-input multiple-output (CF-mMIMO) systems are investigated under spatially correlated fading channels using realistic…

Information Theory · Computer Science 2025-01-06 Zeping Sui , Hien Quoc Ngo , Michail Matthaiou , Lajos Hanzo

An active reconfigurable intelligent surface (RIS) has been shown to be able to enhance the sum-of-degrees-of-freedom (DoF) of a two-user multiple-input multiple-output (MIMO) interference channel (IC) with equal number of antennas at each…

Information Theory · Computer Science 2023-07-12 Shuo Zheng , Bojie Lv , Tong Zhang , Yinfei Xu , Gaojie Chen , Rui Wang , P. C. Ching

This paper investigates the reconfigurable reflecting surface (RIS)-aided multiple-input-single-output (MISO) systems with imperfect channel state information (CSI), where RIS-related channels are modeled by Rician fading. Considering the…

Information Theory · Computer Science 2021-07-13 Kangda Zhi , Cunhua Pan , Hong Ren , Kezhi Wang , Maged Elkashlan

Reconfigurable intelligent surface (RIS) is considered to be an energy-efficient approach to reshape the wireless environment for improved throughput. Its passive feature greatly reduces the energy consumption, which makes RIS a promising…

Information Theory · Computer Science 2020-01-20 Keke Ying , Zhen Gao , Shanxiang Lyu , Yongpeng Wu , Hua Wang , Mohamed-Slim Alouini

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

This letter investigates the secure communication in a reconfigurable intelligent surface (RIS)-aided multiuser massive multiple-input multiple-output (MIMO) system exploiting artificial noise (AN). We first derive a closed-form expression…

Information Theory · Computer Science 2023-01-11 Dan Yang , Jindan Xu , Wei Xu , Yongming Huang , Zhaohua Lu

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

In this paper, we investigate the performance of multiple-input multiple-output (MIMO) fading channels assisted by a reconfigurable intelligent surface (RIS), through the employment of partition-based RIS schemes. The proposed schemes are…

Information Theory · Computer Science 2023-05-09 Andreas Nicolaides , Constantinos Psomas , Ghassan M. Kraidy , Sheng Yang , Ioannis Krikidis

Massive multiple-input multiple-output (MIMO) and reconfigurable intelligent surface (RIS) are two promising technologies for 5G-and-beyond wireless networks, capable of providing large array gain and multiuser spatial multiplexing. Without…

Information Theory · Computer Science 2021-09-07 Trinh Van Chien , Hien Quoc Ngo , Symeon Chatzinotas , Björn Ottersten

Reconfigurable intelligent surface (RIS) is a promising technology that can reshape the electromagnetic environment in wireless networks, offering various possibilities for enhancing wireless channels. Motivated by this, we investigate the…

Information Theory · Computer Science 2024-09-02 Shengguo Meng , Wankai Tang , Weicong Chen , Jifeng Lan , Qun Yan Zhou , Yu Han , Xiao Li , Shi Jin

In this paper, the problem of maximizing the sum-rate is addressed for a multi-user uplink scenario that is assisted by an active reconfigurable intelligent surface (RIS). The maximization is achieved by optimizing the beamforming at the…

Signal Processing · Electrical Eng. & Systems 2026-04-06 Mohamed Shalma , Engy Maher , Ahmed El-Mahdy