A Modular Pragmatic Architecture for Multiuser MIMO with Array-Fed RIS

Fuente: arXiv
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Autori principali: Tiwari, Krishan Kumar, Caire, Giuseppe
Natura: Preprint
Pubblicazione: 2024
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author Tiwari, Krishan Kumar
Caire, Giuseppe
author_facet Tiwari, Krishan Kumar
Caire, Giuseppe
contents We propose a power- and hardware-efficient, pragmatic, modular, multiuser/multibeam array-fed RIS architecture particularly suited to operate in very high frequency bands (high mmWave and sub-THz), where channels are typically sparse in the beamspace and line-of-sight (LOS) is required to achieve an acceptable received signal level. The key module is an active multi-antenna feeder (AMAF) with a small number of active antennas placed in the near field of a RIS with a much larger number of passive controllable reflecting elements. We propose a pragmatic approach to obtain a steerable beam with high gain and very low sidelobes. Then, $K$ independently controlled beams can be achieved by stacking $K$ of such AMAF-RIS modules. Our analysis takes in full account: 1) the near-end crosstalk (NEXT) between the modules, 2) the far-end crosstalk (FEXT) due to the sidelobes; 3) a thorough energy efficiency comparison with respect to conventional active arrays with the same beamforming performance. Overall, we show that the proposed architecture is very attractive in terms of spectral efficiency, ease of implementation (hardware complexity), and energy efficiency.
format Preprint
id arxiv_https___arxiv_org_abs_2405_00572
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle A Modular Pragmatic Architecture for Multiuser MIMO with Array-Fed RIS
Tiwari, Krishan Kumar
Caire, Giuseppe
Signal Processing
Information Theory
Systems and Control
We propose a power- and hardware-efficient, pragmatic, modular, multiuser/multibeam array-fed RIS architecture particularly suited to operate in very high frequency bands (high mmWave and sub-THz), where channels are typically sparse in the beamspace and line-of-sight (LOS) is required to achieve an acceptable received signal level. The key module is an active multi-antenna feeder (AMAF) with a small number of active antennas placed in the near field of a RIS with a much larger number of passive controllable reflecting elements. We propose a pragmatic approach to obtain a steerable beam with high gain and very low sidelobes. Then, $K$ independently controlled beams can be achieved by stacking $K$ of such AMAF-RIS modules. Our analysis takes in full account: 1) the near-end crosstalk (NEXT) between the modules, 2) the far-end crosstalk (FEXT) due to the sidelobes; 3) a thorough energy efficiency comparison with respect to conventional active arrays with the same beamforming performance. Overall, we show that the proposed architecture is very attractive in terms of spectral efficiency, ease of implementation (hardware complexity), and energy efficiency.
title A Modular Pragmatic Architecture for Multiuser MIMO with Array-Fed RIS
topic Signal Processing
Information Theory
Systems and Control
url https://arxiv.org/abs/2405.00572