Wideband Active RISs: Architecture, Modeling, and Beamforming Design

Reconfigurable intelligent surfaces (RISs) have become a candidate for future 6G networks. The concept of active RISs has been recently proposed to overcome the multiplicative fading of RIS aided reflected links. However, due to the frequency-selective channels, the narrowband active RISs suffer fro...

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Bibliographic Details
Published in:IEEE communications letters Vol. 27; no. 7; p. 1
Main Authors: Zhang, Jida, Li, Zhiyi, Zhang, Zijian
Format: Journal Article
Language:English
Published: New York IEEE 01.07.2023
The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subjects:
Algorithms
Array signal processing
Beamforming
Broadband
Communications systems
Discrete Fourier transforms
Modelling
Narrowband
OFDM
Phase shift circuits
Signal to noise ratio
Subcarriers
Time-domain analysis
Wideband
ISSN:1089-7798, 1558-2558
Online Access:Get full text
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Summary:Reconfigurable intelligent surfaces (RISs) have become a candidate for future 6G networks. The concept of active RISs has been recently proposed to overcome the multiplicative fading of RIS aided reflected links. However, due to the frequency-selective channels, the narrowband active RISs suffer from a large performance loss in wideband scenarios. To address this issue, in this letter, we propose wideband active RISs, including their architecture, modeling, and beamforming design. Specifically, the key idea of wideband active RISs is to divide all subcarriers into several groups and the subcarriers in each group are configured by a single amplifying and phase-shift circuit. Based on this architecture, we derive the frequency-domain channel model and noise model of a wideband active RIS aided communication system. Then, we formulate a beamforming design problem for sum-rate maximization, and a joint transmit precoding and reflect beamforming algorithm is proposed to solve the problem. Simulation results verify the significant performance improvement of the proposed wideband RISs in wideband scenarios.
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ISSN:1089-7798
1558-2558
DOI:10.1109/LCOMM.2023.3274433