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We consider a practical spatially correlated reconfigurable intelligent surface (RIS)-aided cell-free (CF) massive multiple-input-multiple-output (mMIMO) system with multi-antenna access points (APs) over spatially correlated Rician fading…

Information Theory · Computer Science 2022-09-29 Enyu Shi , Jiayi Zhang , Zhe Wang , Derrick Wing Kwan Ng , Bo Ai

This paper explores the use of reconfigurable intelligent surfaces (RIS) in mitigating cross-system interference in spectrum sharing and secure wireless applications. Unlike conventional RIS that can only adjust the phase of the incoming…

Information Theory · Computer Science 2023-07-03 Fangzhou Wang , A. Lee Swindlehurst

This work considers the uplink (UL) of a multi-cell massive MIMO system with $L$ cells, having each $K$ mono-antenna users communicating with an $N-$antennas base station (BS). The channel model involves Rician fading with distinct per-user…

Information Theory · Computer Science 2018-12-18 Ikram Boukhedimi , Abla Kammoun , Mohamed-Slim Alouini

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

Active reconfigurable intelligent surfaces (RISs) employ amplification to overcome attenuation caused by the RIS cascaded link. In this paper, we analyze the effects of phase errors and channel aging in active simultaneously transmitting…

Information Theory · Computer Science 2025-10-16 Jun Qian , Ross Murch , Khaled B. Letaief

Semantic communication, which focuses on conveying the meaning of information rather than exact bit reconstruction, has gained considerable attention in recent years. Meanwhile, reconfigurable intelligent surface (RIS) is a promising…

Information Theory · Computer Science 2023-06-30 Jiajia Shi , Tse-Tin Chan , Haoyuan Pan , Tat-Ming Lok

Pilot contamination is a limiting factor in multicell massive multiple-input multiple-output (MIMO) systems because it can severely impair channel estimation. Prior works have suggested coordinating pilot design across cells in order to…

Information Theory · Computer Science 2020-08-13 Kaiming Shen , Hei Victor Cheng , Xihan Chen , Yonina C. Eldar , Wei Yu

Cognitive radio has been proposed to alleviate the scarcity of available spectrum caused by the significant demand for wideband services and the fragmentation of spectrum resources. However, sensing performance is quite poor due to the low…

Information Theory · Computer Science 2023-10-24 Hao Xie , Dong Li , Bowen Gu

Reconfigurable Intelligent Surface (RIS) is a promising solution to reconfigure the wireless environment in a controllable way. To compensate for the double-fading attenuation in the RIS-aided link, a large number of passive reflecting…

Information Theory · Computer Science 2021-03-02 Ruizhe Long , Ying-Chang Liang , Yiyang Pei , Erik G. Larsson

Reconfigurable intelligent surface (RIS) has become a promising technology for enhancing the reliability of wireless communications, which is capable of reflecting the desired signals through appropriate phase shifts. However, the intended…

Signal Processing · Electrical Eng. & Systems 2021-03-03 Bo Yang , Xuelin Cao , Chongwen Huang , Chau Yuen , Lijun Qian , Marco Di Renzo

Mutual Coupling (MC) emerges as an inherent feature in Reconfigurable Intelligent Surfaces (RISs), particularly, when they are fabricated with sub-wavelength inter-element spacing. Hence, any physically-consistent model of the RIS operation…

Information Theory · Computer Science 2024-06-11 Dilki Wijekoon , Amine Mezghani , George C. Alexandropoulos , Ekram Hossain

Until now, researchers in wireless communications have mainly focused their attention on slowly time-varying designs of reconfigurable intelligent surfaces (RISs), where the spatial-phase gradient across the RIS is varied at the rate equal…

Signal Processing · Electrical Eng. & Systems 2024-01-30 Francesco Verde , Donatella Darsena , Vincenzo Galdi

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

Reconfigurable intelligent surface (RIS) can manipulate the wireless communication environment by controlling the coefficients of RIS elements. However, due to the large number of passive RIS elements without signal processing capability,…

Information Theory · Computer Science 2021-01-26 Xiuhong Wei , Decai Shen , Linglong Dai

Reconfigurable intelligent surfaces (RISs) become promising for enhancing non-orthogonal multiple access (NOMA) systems, i.e., enhancing the channel quality and altering the SIC orders. Invoked by stochastic geometry methods, we investigate…

Information Theory · Computer Science 2021-03-04 Chao Zhang , Wenqiang Yi , Yuanwei Liu , Qiang Wang

Reconfigurable Intelligent Surfaces (RIS) are a new paradigm which, with judicious deployment and alignment, can enable more favorable propagation environments and better wireless network design. As such, they can offer a number of…

Information Theory · Computer Science 2022-12-05 Jiayu Mao , Aylin Yener

New reconfigurable intelligent surface (RIS) based amplitude and phase modulation schemes are proposed as an evolution how the phase-only modulation schemes available in the literature. Explicitly, both the amplitude-phase shift keying…

Information Theory · Computer Science 2023-01-25 Qingchao Li , Mohammed El-Hajjar , Ibrahim Hemadeh , Arman Shojaeifard , Alain A. M. Mourad , Lajos Hanzo

In this paper, we consider a reconfigurable intelligence surface (RIS) aided uplink multiuser multi-input multi-output (MIMO) orthogonal frequency division multiplexing (OFDM) system, where the receiver is assumed to conduct low-complexity…

Information Theory · Computer Science 2022-08-31 Mingyang Yue , Lei Liu , Xiaojun Yuan

Reconfigurable intelligent surfaces (RISs) are expected to make future 6G networks more connected and resilient against node failures, due to their ability to introduce controllable phase-shifts onto impinging electromagnetic waves and…

Information Theory · Computer Science 2023-08-22 Mohammed S. Al-Abiad , Mohammad Javad-Kalbasi , Shahrokh Valaee

The reconfigurable intelligent surface (RIS) technology for metasurfaces is ushering in a new paradigm for wireless communication systems. It provides an accessible way for controlling the interaction between electromagnetic waves with the…

Signal Processing · Electrical Eng. & Systems 2026-01-21 P. H. C. de Souza , M. Khazaee , L. L. Mendes