Over-the-Air Semantic Alignment with Stacked Intelligent Metasurfaces

Fuente: arXiv
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Auteurs principaux: Pandolfo, Mario Edoardo, Stylianopoulos, Kyriakos, Alexandropoulos, George C., Di Lorenzo, Paolo
Format: Preprint
Publié: 2025
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author Pandolfo, Mario Edoardo
Stylianopoulos, Kyriakos
Alexandropoulos, George C.
Di Lorenzo, Paolo
author_facet Pandolfo, Mario Edoardo
Stylianopoulos, Kyriakos
Alexandropoulos, George C.
Di Lorenzo, Paolo
contents Semantic communication systems aim to transmit task-relevant information between devices capable of artificial intelligence, but their performance can degrade when heterogeneous transmitter-receiver models produce misaligned latent representations. Existing semantic alignment methods typically rely on additional digital processing at the transmitter or receiver, increasing overall device complexity. In this work, we introduce the first over-the-air semantic alignment framework based on stacked intelligent metasurfaces (SIM), which enables latent-space alignment directly in the wave domain, reducing substantially the computational burden at the device level. We model SIMs as trainable linear operators capable of emulating both supervised linear aligners and zero-shot Parseval-frame-based equalizers. To realize these operators physically, we develop a gradient-based optimization procedure that tailors the metasurface transfer function to a desired semantic mapping. Experiments with heterogeneous vision transformer (ViT) encoders show that SIMs can accurately reproduce both supervised and zero-shot semantic equalizers, achieving up to 90% task accuracy in regimes with high signal-to-noise ratio (SNR), while maintaining strong robustness even at low SNR values.
format Preprint
id arxiv_https___arxiv_org_abs_2512_05657
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Over-the-Air Semantic Alignment with Stacked Intelligent Metasurfaces
Pandolfo, Mario Edoardo
Stylianopoulos, Kyriakos
Alexandropoulos, George C.
Di Lorenzo, Paolo
Signal Processing
Machine Learning
Semantic communication systems aim to transmit task-relevant information between devices capable of artificial intelligence, but their performance can degrade when heterogeneous transmitter-receiver models produce misaligned latent representations. Existing semantic alignment methods typically rely on additional digital processing at the transmitter or receiver, increasing overall device complexity. In this work, we introduce the first over-the-air semantic alignment framework based on stacked intelligent metasurfaces (SIM), which enables latent-space alignment directly in the wave domain, reducing substantially the computational burden at the device level. We model SIMs as trainable linear operators capable of emulating both supervised linear aligners and zero-shot Parseval-frame-based equalizers. To realize these operators physically, we develop a gradient-based optimization procedure that tailors the metasurface transfer function to a desired semantic mapping. Experiments with heterogeneous vision transformer (ViT) encoders show that SIMs can accurately reproduce both supervised and zero-shot semantic equalizers, achieving up to 90% task accuracy in regimes with high signal-to-noise ratio (SNR), while maintaining strong robustness even at low SNR values.
title Over-the-Air Semantic Alignment with Stacked Intelligent Metasurfaces
topic Signal Processing
Machine Learning
url https://arxiv.org/abs/2512.05657