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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

This paper considers an uplink reconfigurable intelligent surface (RIS)-aided massive multiple-input multiple-output (MIMO) system with statistical channel state information (CSI). The RIS is deployed to help conventional massive MIMO…

Signal Processing · Electrical Eng. & Systems 2021-06-17 Kangda Zhi , Cunhua Pan , Hong Ren , Kezhi Wang

In this paper, we focus on the reconfigurable intelligent surface (RIS)-enhanced two-way device-to-device (D2D) multi-pair orthogonal-frequency-division-multiplexing (OFDM) communication systems. Specifically, we maximize the minimum…

Signal Processing · Electrical Eng. & Systems 2020-05-06 Chandan Pradhan , Ang Li , Lingyang Song , Jun Li , Branka Vucetic , Yonghui Li

In this paper, we study the uplink (UL) and downlink (DL) spectral efficiency (SE) of a cell-free massive multiple-input-multiple-output (MIMO) system with Rician fading channels. The phase of the line-of-sight (LoS) path is modeled as a…

Information Theory · Computer Science 2019-11-04 Özgecan Özdogan , Emil Björnson , Jiayi Zhang

Beyond diagonal reconfigurable intelligent surfaces (BD-RIS) can realize the interconnection between reflecting elements through the impedance network, thereby providing a new approach for the performance improvement of integrated sensing…

Information Theory · Computer Science 2026-03-17 Xuejun Cheng , Qian Zhang , Yuhui Jiao , Shiyao Guo , Xiaotong Xu , Guanghui Luo , Ju Liu

This work studies the net sum-rate performance of a distributed reconfigurable intelligent surfaces (RISs)-assisted multi-user multiple-input-single-output (MISO) downlink communication system under imperfect instantaneous-channel state…

Signal Processing · Electrical Eng. & Systems 2023-08-10 Bayan Al-Nahhas , Qurrat-UI-Ain Nadeem , Aryan Kaushik , Anas Chaaban

Reconfigurable intelligent surface (RIS) is a promising reflective radio technology for improving the coverage and rate of future wireless systems by reconfiguring the wireless propagation environment. The current work mainly focuses on the…

Networking and Internet Architecture · Computer Science 2021-03-24 Xuelin Cao , Bo Yang , Hongliang Zhang , Chongwen Huang , Chau Yuen , Zhu Han

The present paper deals with an OFDM-based uplink within a multi-user MIMO (MU-MIMO) system where a massive MIMO approach is employed. In this context, the linear detectors Minimum Mean-Squared Error (MMSE), Zero Forcing (ZF) and Maximum…

The reconfigurable intelligent surface (RIS)-assisted sparse code multiple access (RIS-SCMA) is an attractive scheme for future wireless networks. In this letter, for the first time, the RIS phase shifts of the uplink RIS-SCMA system are…

Information Theory · Computer Science 2021-12-01 Ibrahim Al-Nahhal , Octavia A. Dobre , Ertugrul Basar , Telex M. N. Ngatched , Salama Ikki

Mutual Coupling (MC) is an unavoidable feature in Reconfigurable Intelligent Surfaces (RISs) with sub-wavelength inter-element spacing. Its inherent presence naturally leads to non-local RIS structures, which can be efficiently described…

Information Theory · Computer Science 2024-04-09 Dilki Wijekoon , Amine Mezghani , George C. Alexandropoulos , Ekram Hossain

Recently, simultaneously transmitting and reflecting reconfigurable intelligent surfaces (STAR-RISs) have received significant research interest. The employment of large STAR-RIS and high-frequency signaling inevitably make the near-field…

Information Theory · Computer Science 2023-06-27 Haochen Li , Yuanwei Liu , Xidong Mu , Yue Chen , Zhiwen Pan , Yonina C. Eldar

Intelligent reflecting surfaces (IRSs) constitute a disruptive wireless communication technique capable of creating a controllable propagation environment. In this paper, we propose to invoke an IRS at the cell boundary of multiple cells to…

Signal Processing · Electrical Eng. & Systems 2020-04-27 Cunhua Pan , Hong Ren , Kezhi Wang , Wei Xu , Maged Elkashlan , Arumugam Nallanathan , Lajos Hanzo

In this paper, a wideband cell-free multi-stream multi-user Multiple-Input Multiple-Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) system is considered operating within a smart wireless environment enabled by multiple…

Signal Processing · Electrical Eng. & Systems 2026-01-21 Konstantinos D. Katsanos , George C. Alexandropoulos

Terahertz (THz) cell-free massive multiple-input-multiple-output (mMIMO) networks have been envisioned as a prospective technology for achieving higher system capacity, improved performance, and ultra-high reliability in 6G networks.…

Signal Processing · Electrical Eng. & Systems 2024-05-14 Xin Su , Ruisi He , Peng Zhang , Bo Ai

Multi-Cell (MC) systems are present in mobile network operations from the first generation to the fifth generation of wireless networks, and considers the signals of all users to a base station (BS) centered in a cell. Cell-Free (CF)…

Information Theory · Computer Science 2022-10-04 E. F. de Almeida , R. C. de Lamare

Smart radio environments aided by reconfigurable intelligent reflecting surfaces (RIS) have attracted much research attention recently. We propose a joint optimization strategy for beamforming, RIS phases, and power allocation to maximize…

Information Theory · Computer Science 2022-08-02 Athira Subhash , Abla Kammoun , Ahmed Elzanaty , Sheetal Kalyani , Yazan H. Al-Badarneh , Mohamed-Slim Alouini

User-centric (UC) based cell-free (CF) structures can provide the benefits of coverage enhancement for millimeter wave (mmWave) multiple input multiple output (MIMO) systems, which is regarded as the key technology of the reliable and…

Information Theory · Computer Science 2022-05-10 Yingrong Zhong , Yashuai Cao , Tiejun Lv

Reconfigurable intelligent surface (RIS) is an emerging technology for future wireless communication systems. In this work, we consider downlink spatial multiplexing enabled by the RIS for weighted sum-rate (WSR) maximization. In the…

Signal Processing · Electrical Eng. & Systems 2022-09-22 Bile Peng , Jan-Aike Termöhlen , Cong Sun , Danping He , Ke Guan , Tim Fingscheidt , Eduard A. Jorswieck

We consider the combination of uplink code-domain non-orthogonal multiple access (NOMA) with massive multiple-input multiple-output (MIMO) and reconfigurable intelligent surfaces (RISs). We assume a setup in which the base station (BS) is…

Information Theory · Computer Science 2022-02-22 Bashar Tahir , Stefan Schwarz , Markus Rupp

In this paper, we deploy a full-wave FDTD paradigm to investigate the effect of reconfigurable intelligent surface (RIS) -- switchable frequency-selective surfaces (FSS) -- on generic massive MIMO uplink channel's eigenspace structure. We…

Applied Physics · Physics 2019-11-12 Debdeep Sarkar , Said Mikki , Yahia Antar
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