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Multilayered Intelligent Reflecting Surface for Long-Range Underwater Acoustic Communication

Yu Luo, Lina Pu, Aijun Song

TL;DR

This work introduces ML-ARIS, a multilayered acoustic RIS for underwater communications that enables passive IQ modulation on a single reflector by independently tuning the load on stacked PZT disks. It pairs this multilayer reflector with a novel three-tier matching network to maintain stable impedance under environmental changes such as temperature, depth, and incident angle, enabling precise beam steering with low side lobes. The authors validate the concept through COMSOL simulations and tank experiments, showing controllable amplitude and phase, and demonstrate improved directivity and interference reduction compared to traditional 1- or 2-bit RIS coding. Overall, ML-ARIS offers a scalable approach to boost range and data rate in underwater acoustic networks by enabling high-resolution, environment-robust beamforming and leveraging advanced array processing techniques like MVDR.

Abstract

This article introduces a multilayered acoustic reconfigurable intelligent surface (ML-ARIS) architecture designed for the next generation of underwater communications. ML-ARIS incorporates multiple layers of piezoelectric material in each acoustic reflector, with the load impedance of each layer independently adjustable via a control circuit. This design increases the flexibility in generating reflected signals with desired amplitudes and orthogonal phases, enabling passive in-phase and quadrature (IQ) modulation using a single acoustic reflector. Such a feature enables precise beam steering, enhancing sound levels in targeted directions while minimizing interference in surrounding environments. Extensive simulations and tank experiments were conducted to verify the feasibility of ML-ARIS. The experimental results indicate that implementing IQ modulation with a multilayer structure is indeed practical in real-world scenarios, making it possible to use a single reflection unit to generate reflected waves with high-resolution amplitudes and phases.

Multilayered Intelligent Reflecting Surface for Long-Range Underwater Acoustic Communication

TL;DR

This work introduces ML-ARIS, a multilayered acoustic RIS for underwater communications that enables passive IQ modulation on a single reflector by independently tuning the load on stacked PZT disks. It pairs this multilayer reflector with a novel three-tier matching network to maintain stable impedance under environmental changes such as temperature, depth, and incident angle, enabling precise beam steering with low side lobes. The authors validate the concept through COMSOL simulations and tank experiments, showing controllable amplitude and phase, and demonstrate improved directivity and interference reduction compared to traditional 1- or 2-bit RIS coding. Overall, ML-ARIS offers a scalable approach to boost range and data rate in underwater acoustic networks by enabling high-resolution, environment-robust beamforming and leveraging advanced array processing techniques like MVDR.

Abstract

This article introduces a multilayered acoustic reconfigurable intelligent surface (ML-ARIS) architecture designed for the next generation of underwater communications. ML-ARIS incorporates multiple layers of piezoelectric material in each acoustic reflector, with the load impedance of each layer independently adjustable via a control circuit. This design increases the flexibility in generating reflected signals with desired amplitudes and orthogonal phases, enabling passive in-phase and quadrature (IQ) modulation using a single acoustic reflector. Such a feature enables precise beam steering, enhancing sound levels in targeted directions while minimizing interference in surrounding environments. Extensive simulations and tank experiments were conducted to verify the feasibility of ML-ARIS. The experimental results indicate that implementing IQ modulation with a multilayer structure is indeed practical in real-world scenarios, making it possible to use a single reflection unit to generate reflected waves with high-resolution amplitudes and phases.

Paper Structure

This paper contains 30 sections, 19 equations, 16 figures, 1 table.

Table of Contents

  1. Introduction
  2. Related Work
  3. Motivation of Multilayered UA-RIS
  4. Necessity of Flexible Reflection Control
  5. Challenges of Flexible Reflection Control
  6. Previous Solution of Flexible Reflection Control
  7. Disadvantages of Previous Work
  8. Hardware Architecture
  9. Multilayered Acoustic Reflector
  10. Control Circuit Design
  11. How IQ Modulation Works with ML-ARIS
  12. Enhanced Matching Network
  13. Necessity for a New Matching Network
  14. Water temperature & depth
  15. Incident angle
  16. ...and 15 more sections

Figures (16)

  • Figure 1: IQ modulation implemented with separated reflectors.
  • Figure 2: The structure of a multilayered acoustic reflector.
  • Figure 3: Control circuit of a two-layer acoustic reflector.
  • Figure 4: Impedance variation of PZT disk 1 with frequency and temperature.
  • Figure 5: Impedances of PZT layers under varying incident angles of acoustic waves: (a) Resistance component. (b) Reactance component.
  • ...and 11 more figures