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arxiv: 2604.15232 · v1 · submitted 2026-04-16 · 📡 eess.SP

Physical Layer Security Performance of Pinching-Antenna Systems With In-Waveguide Attenuation

Xiaochen Zhang , Haitao Du , Yanyu Cheng , Yushen Lin , Kah Chan Teh This is my paper

Pith reviewed 2026-05-10 10:15 UTC · model grok-4.3

classification 📡 eess.SP
keywords pinching antennaphysical layer securitywaveguide attenuationsecrecy outage probabilityergodic secrecy capacitysecure wireless communicationperformance bounds
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The pith

Pinching-antenna systems achieve better secrecy outage probability and ergodic secrecy capacity than fixed-antenna systems once realistic waveguide attenuation is included.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper examines physical-layer security for pinching-antenna systems by replacing idealized lossless waveguide models with one that includes attenuation. It sets up a base-station transmitter, a legitimate receiver, and a passive eavesdropper, then derives closed-form upper and lower bounds on secrecy outage probability and ergodic secrecy capacity. These bounds are compared against conventional fixed-antenna baselines. The comparison shows that the pinching-antenna configuration remains superior under the loss-inclusive model. This matters for practical deployment because any real waveguide will exhibit attenuation, so security claims must survive that condition.

Core claim

In a secure communication scenario consisting of a base station, legitimate user, and passive eavesdropper, expressions for closed-form upper and lower bounds on both the secrecy outage probability and ergodic secrecy capacity are derived for pinching-antenna systems under an attenuation-incorporated waveguide model, and numerical results indicate that the PA system outperforms conventional fixed-antenna systems.

What carries the argument

The attenuation-incorporated waveguide model together with closed-form bounding derivations for secrecy outage probability and ergodic secrecy capacity.

If this is right

  • Pinching-antenna placement can be optimized while still preserving a secrecy advantage over fixed antennas.
  • System designers gain analytical expressions that allow direct evaluation of security metrics without Monte-Carlo simulation.
  • Conventional fixed-antenna links will require higher transmit power or additional security measures to match the secrecy performance of an attenuated pinching-antenna link.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The same bounding approach could be extended to multi-user or multi-eavesdropper geometries without changing the core model.
  • If attenuation varies along the waveguide, dynamic pinching positions might further improve the secrecy margin beyond the static case examined.
  • Hardware implementations would need to verify that the pinching mechanism itself does not introduce additional loss or phase noise not captured in the current model.

Load-bearing premise

The derivations rely on one specific three-node secure-communication geometry and on an attenuation model whose parameters match real hardware.

What would settle it

A laboratory measurement of secrecy outage probability and ergodic secrecy capacity in a physical pinching-antenna prototype with documented waveguide losses, compared side-by-side with an identical fixed-antenna setup under the same transmit power and channel conditions.

Figures

Figures reproduced from arXiv: 2604.15232 by Haitao Du, Kah Chan Teh, Xiaochen Zhang, Yanyu Cheng, Yushen Lin.

Figure 1
Figure 1. Figure 1: System model consisting of a single-user direct trans [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 5
Figure 5. Figure 5: ESCs of the PA and PA in the high-SNR regime. which is consistent with the theoretical results in Corollary 1. For performance comparison, we consider a conventional FA system as the benchmark, which is located at the signal source [0, 0, d] and is unaffected by in-waveguide attenuation. It is observed that the PA has a consistently lower SOP than the FA across the evaluated SNR range, which reveals that t… view at source ↗
read the original abstract

Pinching antenna (PA) systems have recently gained significant attention. While their physical-layer security (PLS) is being explored, most studies rely on idealized lossless models, ignoring practical waveguide attenuation. In this paper, we investigate the PLS performance of PA systems under a more realistic attenuation-incorporated waveguide model. Specifically, we investigate a PA system-based secure communication scenario consisting of a base station (BS), a legitimate user, and a passive eavesdropper. We derive expressions for closed-form upper and lower bounds on both the secrecy outage probability (SOP) and ergodic secrecy capacity (ESC). The results indicate that the PA system outperforms conventional fixed-antenna systems.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The manuscript investigates the physical-layer security (PLS) performance of pinching-antenna (PA) systems under a realistic waveguide model that incorporates in-waveguide attenuation. It considers a secure communication scenario with a base station, a legitimate user, and a passive eavesdropper, and derives closed-form upper and lower bounds on the secrecy outage probability (SOP) and ergodic secrecy capacity (ESC). Numerical results are used to conclude that the PA system outperforms conventional fixed-antenna systems.

Significance. If the derived bounds are accurate and the attenuation model is representative of practical waveguides, the work fills a gap left by prior idealized lossless PA analyses and provides concrete guidance on PLS advantages of PA deployments. The closed-form bounds and explicit comparison to fixed-antenna baselines constitute a useful contribution to the emerging PA literature.

major comments (2)
  1. [Section II (System Model)] The central outperformance claim rests on the accuracy of the attenuation-incorporated waveguide model, yet the manuscript provides no empirical validation, measured attenuation coefficients, or references to experimental waveguide data. This assumption is load-bearing for the practical relevance of the SOP/ESC bounds and the comparison to fixed-antenna systems.
  2. [Section IV (Numerical Results)] The numerical results in Section IV demonstrate PA superiority, but no sensitivity analysis is shown with respect to the attenuation parameter or waveguide length; without this, it is unclear whether the reported gains hold under realistic variations in the model.
minor comments (2)
  1. [Abstract and Section III] The abstract states that closed-form bounds are derived, but the tightness of the upper and lower bounds relative to exact expressions is not quantified in the text or figures.
  2. [Section II] Notation for the pinching-antenna positions and the eavesdropper location should be introduced earlier and used consistently in the bound derivations.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive comments, which help improve the clarity and robustness of our analysis. We respond to each major comment below and indicate the revisions made to the manuscript.

read point-by-point responses

  1. Referee: [Section II (System Model)] The central outperformance claim rests on the accuracy of the attenuation-incorporated waveguide model, yet the manuscript provides no empirical validation, measured attenuation coefficients, or references to experimental waveguide data. This assumption is load-bearing for the practical relevance of the SOP/ESC bounds and the comparison to fixed-antenna systems.

    Authors: The waveguide attenuation model in Section II follows standard propagation theory for lossy dielectric waveguides, with the attenuation coefficient treated as a fixed but realistic parameter. While the original manuscript did not include new experimental measurements, the parameter values align with those commonly used in the PA literature. To address the concern, we have added references to experimental waveguide studies that report measured attenuation coefficients for comparable setups, thereby grounding the model in practical data without changing the derived bounds or numerical conclusions. revision: yes

  2. Referee: [Section IV (Numerical Results)] The numerical results in Section IV demonstrate PA superiority, but no sensitivity analysis is shown with respect to the attenuation parameter or waveguide length; without this, it is unclear whether the reported gains hold under realistic variations in the model.

    Authors: We agree that sensitivity analysis strengthens the interpretation of the results. In the revised manuscript, we have added new numerical evaluations in Section IV that explicitly vary the attenuation coefficient and waveguide length over ranges representative of practical deployments. These additional plots and accompanying discussion confirm that the reported advantages in SOP and ESC for the PA system remain consistent across these variations. revision: yes

Circularity Check

0 steps flagged

No significant circularity in derivation chain

full rationale

The paper introduces an attenuation-incorporated waveguide model as an input assumption for a secure communication scenario and derives closed-form upper/lower bounds on SOP and ESC from it, then compares performance to fixed-antenna baselines. No quoted equations or steps reduce the bounds or outperformance claim to a self-definition, fitted parameter renamed as prediction, or self-citation chain. The central results are model-dependent but mathematically independent of the target conclusions once the model is fixed; external validation of the model is a separate correctness issue, not circularity.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract provides insufficient detail to identify specific free parameters, axioms, or invented entities; standard wireless channel and attenuation models are implicitly assumed but not enumerated.

pith-pipeline@v0.9.0 · 5420 in / 992 out tokens · 21248 ms · 2026-05-10T10:15:17.056429+00:00 · methodology

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Reference graph

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