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This paper proposes a two-stage approach for passive and active beamforming in multiple-input multiple-output (MIMO) interference channels (ICs) assisted by a beyond-diagonal reconfigurable intelligent surface (BD-RIS). In the first stage,…

Information Theory · Computer Science 2025-03-26 Ignacio Santamaria , Mohammad Soleymani , Eduard Jorswieck , Jesus Gutierrez

The linear minimal mean square error (LMMSE) estimator for active reconfigurable intelligent surface (RIS)-aided wireless systems is formulated. Furthermore, based on the moment-matching method, we employ the Gamma distribution to…

Information Theory · Computer Science 2023-01-25 Qingchao Li , Mohammed El-Hajjar , Ibrahim Hemadeh , Deepa Jagyasi , Arman Shojaeifard , Lajos Hanzo

Rate-Splitting Multiple Access (RSMA) for multi-user downlink operates by splitting the message for each user equipment (UE) into a private message and a set of common messages, which are simultaneously transmitted by means of superposition…

Signal Processing · Electrical Eng. & Systems 2022-03-09 Daesung Yu , Seok-Hwan Park , Osvaldo Simeone , Shlomo Shamai

Introduced with the advent of statistical wireless channel models for high mobility communications and having a profound role in communication-centric (CC) integrated sensing and communications (ISAC), the doubly-dispersive (DD) channel…

Reconfigurable intelligent surfaces (RISs) have recently emerged as a promising technology that can achieve high spectrum and energy efficiency for future wireless networks by integrating a massive number of low-cost and passive reflecting…

Information Theory · Computer Science 2021-02-05 Minchae Jung , Walid Saad , Merouane Debbah , Choong Seon Hong

Within the context of massive machine-type communications+, reconfigurable intelligent surfaces (RISs) represent a promising technology to boost system performance in scenarios with poor channel conditions. Considering single-antenna…

Signal Processing · Electrical Eng. & Systems 2026-01-28 Sergi Liesegang , Antonio Pascual-Iserte , Olga Muñoz , Alessio Zappone

Antenna selection is capable of reducing the hardware complexity of massive multiple-input multiple-output (MIMO) networks at the cost of certain performance degradation. Reconfigurable intelligent surface (RIS) has emerged as a…

Information Theory · Computer Science 2020-09-17 Jinglian He , Kaiqiang Yu , Yuanming Shi , Yong Zhou , Wei Chen , Khaled B. Letaief

Reconfigurable intelligent surfaces (RISs) and cell-free massive multiple-input multiple-output (CF-mMIMO) are effective solutions for mitigating large path loss and inter-cell interference in terahertz (THz) systems. However, passive RISs…

Signal Processing · Electrical Eng. & Systems 2025-05-14 Mario R. Camana , Zaid Abdullah , Carla E. Garcia , Chandan Kumar Sheemar , Eva Lagunas , Symeon Chatzinotas

Different from conventional passive reconfigurable intelligent surfaces (RISs), incident signals and thermal noise can be amplified at active RISs. By exploiting the amplifying capability of active RISs, noticeable performance improvement…

Information Theory · Computer Science 2025-04-02 Jinho Yang , Hyeongtaek Lee , Junil Choi

It is challenging to precisely configure the phase shifts of the reflecting elements at the reconfigurable intelligent surface (RIS) due to inherent hardware impairments (HIs). In this paper, the mean square error (MSE) performance is…

Information Theory · Computer Science 2022-08-17 Jingwen Zhao , Ming Chen , Cunhua Pan , Zhiyang Li , Gui Zhou , Xiao Chen

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

Intelligent reflecting surfaces (IRS) have emerged as a promising technology to enhance the performance of wireless communication systems. By actively manipulating the wireless propagation environment, IRS enables efficient signal…

Signal Processing · Electrical Eng. & Systems 2023-08-21 Chandan Kumar Sheemar , Sourabh Solanki , Jorge Querol , Sumit Kumar , Symeon Chatzinotas

With the rapid development of high-speed railway systems and railway wireless communication, the application of ultra-wideband millimeter wave band is an inevitable trend. However, the millimeter wave channel has large propagation loss and…

Information Theory · Computer Science 2022-11-29 Panpan Li , Yong Niu , Hao Wu , Zhu Han , Bo Ai , Ning Wang , Zhangdui Zhong

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

This paper considers a simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS)-aided cell-free massive multiple-input multiple-output (CF-mMIMO) system, accounting for imperfect hardware in spatially…

Information Theory · Computer Science 2024-08-27 Zeping Sui , Hien Quoc Ngo , Michail Matthaiou

This paper considers a cell-free integrated sensing and communication (ISAC) MIMO system, where distributed MIMO access points (APs) jointly serve the communication users and sense the target. For this setup, we derive a sensing SNR for…

Information Theory · Computer Science 2024-02-26 Umut Demirhan , Ahmed Alkhateeb

The reconfigurable intelligent surface (RIS) is useful to effectively improve the coverage and data rate of end-to-end communications. In contrast to the well-studied coverage-extension use case, in this paper, multiple RIS panels are…

Information Theory · Computer Science 2023-01-31 Zhong Zheng , Siqiang Wang , Zesong Fei , Zhi Sun , Jinhong Yuan

In this paper, to tackle the blockage issue in massive multiple-input-multiple-output (mMIMO) systems, a reconfigurable intelligent surface (RIS) is seamlessly deployed to support devices with ultra-reliable and low-latency communications…

Signal Processing · Electrical Eng. & Systems 2024-05-14 Qihao Peng , Hong Ren , Cunhua Pan , Maged Elkashlan , Ana Garcia Armada , Petar Popovski

In this paper, we investigate a double-active-reconfigurable intelligent surface (RIS)-aided downlink wireless communication system, where a multi-antenna base station (BS) serves multiple single-antenna users with both double reflection…

Signal Processing · Electrical Eng. & Systems 2024-08-26 Boshi Wang , Cunhua Pan , Hong Ren , Zhiyuan Yu , Yang Zhang , Mengyu Liu , Gui Zhou

Reconfigurable Intelligent Surfaces (RISs), comprising large numbers of low-cost and passive metamaterials with tunable reflection properties, have been recently proposed as an enabler for programmable radio propagation environments.…

Information Theory · Computer Science 2021-09-17 Aris L. Moustakas , George C. Alexandropoulos , Mérouane Debbah