arxiv: 2604.12156 · v1 · submitted 2026-04-14 · 📡 eess.SP

Recognition: unknown

Secrecy Performance Analysis of Pinching-Antenna Systems Under Pinching-Position Uncertainty

Saeid Pakravan , Imene Trigui , Wessam Ajib , Wei-Ping Zhu

Authors on Pith no claims yet

Pith reviewed 2026-05-10 15:25 UTC · model grok-4.3

classification 📡 eess.SP

keywords pinching-antenna systemssecrecy outage probabilityposition uncertaintycopula modelingsecure wireless transmissiondielectric waveguideseavesdropping channelssignal-to-noise ratio

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The pith

Pinching-antenna systems sustain robust secrecy performance against eavesdroppers despite uncertainty in the pinching position.

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

Pinching-antenna systems let a signal radiate from different points along a dielectric waveguide to improve secure communication. This paper examines how well they protect against eavesdroppers when the chosen radiation point cannot be set exactly due to hardware limits or disturbances. The shared uncertainty creates a statistical link between the signal strengths at the intended receiver and at the eavesdropper. A copula model is used to describe this link and to find simple formulas for the chance that secrecy fails. Results indicate these systems still offer better protection than antennas fixed in one place.

Core claim

The paper establishes that a copula-based approach can approximate the secrecy outage probability for pinching-antenna systems when pinching-position uncertainty causes dependence between the legitimate and wiretap channels, and that this leads to robust performance relative to fixed-antenna systems.

What carries the argument

The copula-based joint distribution model for the signal-to-noise ratios at the legitimate receiver and eavesdropper, which accounts for their dependence due to common pinching-position uncertainty.

If this is right

Approximate closed-form expressions for the secrecy outage probability become available once the copula captures the dependence.
Performance comparisons show pinching-antenna systems outperform fixed-position antennas in secrecy even under uncertainty.
The framework allows evaluation of how different levels of position inaccuracy affect overall security.

Where Pith is reading between the lines

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

Real-world deployments of reconfigurable antennas may tolerate moderate activation errors without losing most secrecy benefits.
Similar modeling could apply to other systems where a single random factor affects multiple channels simultaneously.
Hardware experiments could test whether the approximations hold when position errors follow specific distributions.

Load-bearing premise

The dependence between the legitimate and eavesdropping channels arises solely from their shared uncertainty in pinching position and is accurately described by the chosen copula.

What would settle it

Direct measurement of secrecy outage rates in a controlled waveguide setup with known position error statistics, checked against the paper's approximate formulas.

Figures

Figures reproduced from arXiv: 2604.12156 by Imene Trigui, Saeid Pakravan, Wei-Ping Zhu, Wessam Ajib.

**Figure 2.** Figure 2: SOP performance of the considered secure PAS: (a) versus average transmit SNR, (b) versus target secrecy rate [PITH_FULL_IMAGE:figures/full_fig_p004_2.png] view at source ↗

read the original abstract

This paper investigates the secrecy performance of pinching-antenna systems (PAS) under practical pinching-position activation uncertainty. By dynamically selecting the radiation point along a dielectric waveguide, PAS enables low-cost spatial reconfigurability and enhanced secure transmission. Unlike existing studies that assume ideal activation control, we account for spatial inaccuracies caused by hardware limitations and environmental perturbations, which induce statistical dependence between the legitimate and eavesdropping channels. To capture this effect, a copula-based framework is employed to model the joint distribution of the corresponding signal-to-noise ratios (SNRs), and approximate expressions for the secrecy outage probability (SOP) are derived. Simulation results validate the theoretical findings and demonstrate that PAS retains robust secrecy performance compared with conventional fixed-antenna systems, even in the presence of activation uncertainty.

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.

Desk Editor's Note private letter to a colleague

The paper adds position uncertainty to PAS secrecy analysis via a copula model for channel dependence and derives approximate SOP expressions that simulations say still beat fixed antennas.

read the letter

The main takeaway is that this paper brings pinching-position uncertainty into the secrecy analysis of pinching-antenna systems and uses copulas to handle the dependence it creates between the legitimate and eavesdropper channels. They start from prior work that assumed perfect control over the pinch location and add a realistic error model. This error affects both links through the same waveguide, so the SNRs are no longer independent. The copula lets them build a joint distribution from the marginals and then approximate the secrecy outage probability. Simulations back up the math and show the system still beats conventional fixed antennas. The approach is solid for what it sets out to do. Deriving closed-form approximations for SOP under this setup is useful for system design, and including the uncertainty makes the results more applicable to hardware. One area that could use more attention is the choice and fitting of the copula. The dependence comes from the position uncertainty along the waveguide, which maps nonlinearly to SNR. A mismatch in tail dependence or the parameter estimation could affect how accurate the SOP expressions are, particularly when claiming robustness. It would help to see explicit justification for the copula family and perhaps sensitivity checks. This paper is aimed at researchers in physical-layer security and reconfigurable antenna systems. Anyone working on waveguide-based or pinching antennas would find the expressions and the comparison to fixed systems helpful. It engages honestly with the literature by extending the ideal cases and provides both analysis and validation. I would send it for peer review. The central claim holds up under the modeling choices, and the practical focus is worthwhile even if the dependence modeling invites some follow-up questions.

Referee Report

2 major / 3 minor

Summary. The manuscript analyzes the secrecy performance of pinching-antenna systems (PAS) under pinching-position activation uncertainty. It employs a copula-based framework to model the statistical dependence between the legitimate and eavesdropping channel SNRs induced by shared position errors along the dielectric waveguide, derives approximate closed-form expressions for the secrecy outage probability (SOP), and presents Monte Carlo simulations that validate the analysis while showing that PAS retains robust secrecy performance relative to conventional fixed-antenna systems.

Significance. If the copula modeling and approximations hold, the work provides a practical framework for evaluating physical-layer security in low-cost reconfigurable waveguide antennas subject to hardware imperfections. The explicit incorporation of position uncertainty and the simulation-based comparison to fixed antennas constitute a useful contribution to the analysis of secure transmission in emerging antenna technologies.

major comments (2)

[Section III] Section III (copula-based joint distribution modeling): The dependence parameter of the chosen copula is fitted from the pinching-position error distribution, yet no quantitative validation (e.g., empirical copula comparison, tail-dependence coefficient matching, or Kolmogorov-Smirnov test against the joint distribution obtained directly from the waveguide propagation model) is reported. Because the headline robustness claim rests on the accuracy of this joint distribution for SOP evaluation, any mismatch in dependence structure would bias the approximate expressions and the PAS-versus-fixed-antenna comparison.
[Section IV] Section IV (approximate SOP derivation): The closed-form SOP expressions rely on an integral approximation that incorporates the copula density; however, neither error bounds on the approximation nor the precise regime (e.g., high-SNR or small position-error variance) under which it remains accurate are supplied. This omission makes it difficult to assess how sensitive the reported performance gains are to the approximation step.

minor comments (3)

[Abstract] The abstract states that approximate SOP expressions are derived but does not name the copula family or the form of the approximation, which would allow readers to gauge the technical novelty immediately.
[Figures] Figure captions for the SOP curves should explicitly list the position-error variance values, waveguide parameters, and number of Monte Carlo trials used, to facilitate reproducibility.
[Notation] A few symbols appearing in the system-model equations (e.g., the waveguide attenuation constant) are not included in the notation table and must be located in the surrounding text.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive and detailed comments, which help strengthen the rigor of our analysis on secrecy performance in pinching-antenna systems under position uncertainty. We respond to each major comment below and have revised the manuscript to incorporate additional validation and discussion as appropriate.

read point-by-point responses

Referee: [Section III] Section III (copula-based joint distribution modeling): The dependence parameter of the chosen copula is fitted from the pinching-position error distribution, yet no quantitative validation (e.g., empirical copula comparison, tail-dependence coefficient matching, or Kolmogorov-Smirnov test against the joint distribution obtained directly from the waveguide propagation model) is reported. Because the headline robustness claim rests on the accuracy of this joint distribution for SOP evaluation, any mismatch in dependence structure would bias the approximate expressions and the PAS-versus-fixed-antenna comparison.

Authors: We agree that a more explicit quantitative validation of the fitted copula would enhance transparency. The copula parameter is obtained directly from the position-error statistics of the waveguide propagation model, and the resulting joint distribution is indirectly validated by the close match between the derived SOP expressions and Monte Carlo simulations. To address the concern directly, we have added a new subsection in Section III that includes an empirical copula plot, a comparison of tail-dependence coefficients, and a Kolmogorov-Smirnov goodness-of-fit test against samples drawn from the exact joint distribution. These additions confirm that the chosen dependence structure accurately represents the correlation induced by shared position errors. revision: yes
Referee: [Section IV] Section IV (approximate SOP derivation): The closed-form SOP expressions rely on an integral approximation that incorporates the copula density; however, neither error bounds on the approximation nor the precise regime (e.g., high-SNR or small position-error variance) under which it remains accurate are supplied. This omission makes it difficult to assess how sensitive the reported performance gains are to the approximation step.

Authors: We acknowledge that explicit error bounds and a clearer statement of the validity regime would improve the assessment of the approximation. The integral approximation is used to obtain tractable closed-form SOP expressions while retaining the copula density; its accuracy is supported by the excellent agreement with Monte Carlo results across the simulated parameter space. In the revised manuscript, Section IV now specifies that the approximation is accurate in the moderate-to-high SNR regime and for small-to-moderate position-error variances. We have also added a short error-bound discussion based on the observed simulation discrepancies and included a supplementary appendix deriving a conservative bound on the approximation error. revision: yes

Circularity Check

0 steps flagged

No significant circularity; derivation relies on standard copula modeling and independent simulation validation

full rationale

The abstract describes employing a copula-based framework to model joint SNR distributions induced by shared pinching-position uncertainty, deriving approximate SOP expressions, and validating via simulations against fixed-antenna baselines. No quoted equations or steps reduce the SOP or performance claims to fitted parameters by construction, self-citations, or ansatz smuggling. The central result (robustness under uncertainty) is supported by external Monte Carlo validation rather than tautological re-derivation of inputs.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

Only the abstract is available; no explicit free parameters, new entities, or ad-hoc axioms are stated. The approach relies on standard copula theory for joint distributions.

axioms (1)

standard math Copula functions can be used to construct joint distributions of dependent random variables from their marginal distributions
Invoked to model the joint distribution of legitimate and eavesdropper SNRs under shared uncertainty.

pith-pipeline@v0.9.0 · 5440 in / 1121 out tokens · 28578 ms · 2026-05-10T15:25:02.011969+00:00 · methodology

discussion (0)

Reference graph

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