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Metasurface-Enabled Extremely Large-Scale Antenna Systems: Transceiver Architecture, Physical Modeling, and Channel Estimation

Zhengyu Wang, Tiebin Mi, Gui Zhou, Robert C. Qiu

TL;DR

This work tackles the practical scalability of extremely large-scale antenna arrays by introducing Metasurface-enabled Extremely Large-Scale Antenna (MELA) systems that use a reconfigurable transmissive metasurface for over-the-air transceiver-to-antenna coupling and phase control. It develops a physically interpretable end-to-end EM channel model and a distance-aware, decoupled representation that leads to a compact linear channel form, enabling tractable analysis. A two-stage channel-estimation pipeline—coarse dictionary-driven beamspace scanning followed by a refined, symmetry-exploiting estimator for angle and distance—addresses hybrid near-/far-field operation and achieves high-resolution channel acquisition, with HPBW comparable to conventional ELAA. Numerical results from full-wave simulations and parameter studies validate the EM model and demonstrate robust performance gains, highlighting MELA as a practical, scalable path toward future ELAA deployments.

Abstract

Extremely large-scale antenna arrays (ELAAs) have emerged as a pivotal technology for addressing the unprecedented performance demands of next-generation wireless communication systems. To enhance their practicality, we propose metasurface-enabled extremely large-scale antenna (MELA) systems -- novel transceiver architectures that employ reconfigurable transmissive metasurfaces to facilitate efficient over-the-air RF-to-antenna coupling and phase control. This architecture eliminates the need for bulky switch matrices and costly phase-shifter networks typically required in conventional solutions. Physically grounded models are developed to characterize electromagnetic field propagation through individual transmissive unit cells, capturing the fundamental physics of wave transformation and transmission. Additionally, distance-dependent approximate models are introduced, exhibiting structural properties conducive to efficient parameter estimation and signal processing. Based on the channel model, a two stage channel estimation framework is proposed for the scenarios comprising users in the hybrid near- and far-fields. In the first stage, a dictionary-driven beamspace filtering technique enables rapid angular-domain scanning. In the refinement stage, the rotational symmetry of subarrays is exploited to design super-resolution estimators that jointly recover angular and range parameters. An analytical expression for the half-power beamwidth of MELA is derived, revealing its near-optimal spatial resolution relative to conventional ELAA architectures. Numerical experiments further validate the high-resolution of the proposed channel estimation algorithm and the fidelity of the electromagnetic model, positioning the MELA architecture as a highly competitive and forward-looking solution for practical ELAA deployment.

Metasurface-Enabled Extremely Large-Scale Antenna Systems: Transceiver Architecture, Physical Modeling, and Channel Estimation

TL;DR

This work tackles the practical scalability of extremely large-scale antenna arrays by introducing Metasurface-enabled Extremely Large-Scale Antenna (MELA) systems that use a reconfigurable transmissive metasurface for over-the-air transceiver-to-antenna coupling and phase control. It develops a physically interpretable end-to-end EM channel model and a distance-aware, decoupled representation that leads to a compact linear channel form, enabling tractable analysis. A two-stage channel-estimation pipeline—coarse dictionary-driven beamspace scanning followed by a refined, symmetry-exploiting estimator for angle and distance—addresses hybrid near-/far-field operation and achieves high-resolution channel acquisition, with HPBW comparable to conventional ELAA. Numerical results from full-wave simulations and parameter studies validate the EM model and demonstrate robust performance gains, highlighting MELA as a practical, scalable path toward future ELAA deployments.

Abstract

Extremely large-scale antenna arrays (ELAAs) have emerged as a pivotal technology for addressing the unprecedented performance demands of next-generation wireless communication systems. To enhance their practicality, we propose metasurface-enabled extremely large-scale antenna (MELA) systems -- novel transceiver architectures that employ reconfigurable transmissive metasurfaces to facilitate efficient over-the-air RF-to-antenna coupling and phase control. This architecture eliminates the need for bulky switch matrices and costly phase-shifter networks typically required in conventional solutions. Physically grounded models are developed to characterize electromagnetic field propagation through individual transmissive unit cells, capturing the fundamental physics of wave transformation and transmission. Additionally, distance-dependent approximate models are introduced, exhibiting structural properties conducive to efficient parameter estimation and signal processing. Based on the channel model, a two stage channel estimation framework is proposed for the scenarios comprising users in the hybrid near- and far-fields. In the first stage, a dictionary-driven beamspace filtering technique enables rapid angular-domain scanning. In the refinement stage, the rotational symmetry of subarrays is exploited to design super-resolution estimators that jointly recover angular and range parameters. An analytical expression for the half-power beamwidth of MELA is derived, revealing its near-optimal spatial resolution relative to conventional ELAA architectures. Numerical experiments further validate the high-resolution of the proposed channel estimation algorithm and the fidelity of the electromagnetic model, positioning the MELA architecture as a highly competitive and forward-looking solution for practical ELAA deployment.

Paper Structure

This paper contains 13 sections, 3 theorems, 68 equations, 13 figures.

Table of Contents

  1. Introduction
  2. Contributions
  3. Prior Works
  4. Transceiver Architecture and Theoretical Modeling
  5. Channel estimation
  6. Coarse Estimation
  7. Refined estimation
  8. Spatial resolution of the MELA Systems
  9. Numerical Results
  10. Full-wave Simulation
  11. Impact of System Parameters on the Channel
  12. Channel Estimation
  13. conclusion

Key Result

Theorem 1

Suppose that both the receiving antenna and the transmissive unit cell have square apertures with side lengths $d_r$ and $d_t$. Let $\mathbf{e}_{\text{co}}$ be the receiver's polarization unit vector. Then, the average electric field at the $m$-th receiving antenna, due to a source located at positi where the scalars $\mathcal{A}_{mn}$ and $\mathcal{B}_{mnk}$ are defined as Here, $\theta_{nk}$ an

Figures (13)

  • Figure 1: Illustration of the conventional ELAA architecture.
  • Figure 3: Diagram of the transceiver architecture with receiving antennas confined to a localized region.
  • Figure 4: Illustration of different modeling regimes based on the metasurface-receiver distance.
  • Figure 5: Spatial subarray partitioning of the metasurface.
  • Figure 6: Normalized array-factor power versus azimuth angle. Results in red are computed using \ref{['eq:AF']}, whereas those in blue are obtained from the array-factor expression in Eq. (16) of xiong2024design. Left: Three near-field feeds located at distances of $[0.04, 0.05, 0.06]m$; HPBWs of MELA and ELAA are $9.02^\circ$ and $6.85^\circ$, respectively. Right: Three far-field feeds located at distances of $[2.5, 2.6, 2.7]m$; HPBWs are $7.20^\circ$ (MELA) and $6.85^\circ$ (ELAA).
  • ...and 8 more figures

Theorems & Definitions (4)

  • Theorem 1
  • proof
  • Corollary 1
  • Corollary 2