Secure Pinching Antenna-aided ISAC

Ali Ghrayeb; Elmehdi Illi; Marwa Qaraqe

REVIEW 2 major objections 5 minor 1 cited by

Secure Pinching Antenna-aided ISAC

T0 review · 2 major / 5 minor · reviewed 2026-08-06 · deepseek-v4-flash

Challenge this review Re-run · record.json Download PDF Read on arXiv ↗

Pith's one-line read A pinching-antenna ISAC scheme that aligns antennas with users and targets, then optimizes beamforming and artificial noise, is claimed to outperform equidistant and fixed-array baselines by 3-30 dB in illumination power.

desk verdict New problem combination, plausible gains, but the headline numbers sit on an unproven rank-one recovery step that needs fixing before the paper can be trusted. read the letter →

arxiv 2507.13131 v1 pith:MMW5VDIG submitted 2025-07-17 cs.IT eess.SPmath.IT

Elmehdi Illi , Marwa Qaraqe , Ali Ghrayeb This is my paper

classification cs.ITeess.SPmath.IT

keywords schemeisacsystemcommunicationproposedsensingwhiledfrc

verification ladder T0 review T1 audit T2 compute T3 formal

The pith

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

The reading

This letter studies a base station that sends both data and radar-like sensing signals through several long plastic or dielectric tubes called waveguides. Small antennas, called pinching antennas, can be clipped onto these tubes at chosen positions, and the signal traveling inside a tube radiates from each clipped antenna. Moving the clips changes both the path a radio wave takes and which directions it reaches most strongly.

The authors consider a scenario with two jobs at once: delivering private messages to a few legitimate users, and detecting hostile targets that are also trying to overhear those messages. Their design uses two levers. First, it places the antennas on each tube near the users and near the targets, so the channel to both groups is strong. Second, it computes a beamforming vector and an artificial-noise covariance matrix: the beamforming concentrates the useful signal toward the users, and the artificial noise, broadcast in other directions, degrades the targets' ability to decode the users' messages while still helping the sensing echoes.

Numerical simulations compare this scheme with two baselines: pinching antennas spaced evenly along the tubes, and a conventional fixed array of half-wavelength-spaced antennas. The authors report roughly 3 to 4 dB more target illumination power than the evenly spaced pinching antennas and up to 30 dB more than the fixed array. The result is only as strong as the placement heuristic and the optimization steps, and no code or data are released, so the numbers should be read as a promising simulation result rather than a verified system design.

Extended reading notes

Core claim

In the abstract the authors state: 'We show that the proposed scheme outperforms the baseline PA-aided scheme with equidistant PAs by 3 dB in terms of illumination power, while it can provide gains of up to 30 dB of the same metric against a traditional ISAC system with half-wavelength-space uniform linear arrays.' If correct, the heuristic PA placement plus SDR beamforming and artificial-noise design delivers a large sensing-power advantage while preserving secrecy constraints.

Load-bearing premise

The load-bearing premise is that the greedy PA-placement rule in Section III-B (aligning PAs with user and target x-coordinates, Eqs. 14-16) yields a near-optimal antenna configuration for the non-convex problem P1. The paper provides no optimality gap, convergence guarantee, or robustness analysis, and all numerical gains are generated with this rule. A second, related premise is that the rank-one recovery in Section III-C preserves the SINR constraints, which is asserted but not proven.

Share X Bluesky LinkedIn Reddit HN

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Desk Editor's Note

read the letter

Quick read for you. The genuinely new thing here is putting pinching-antenna position tuning together with secrecy-constrained ISAC: earlier PA work did secrecy without sensing or sensing without security, and this is the first to do both in one formulation. The system model is clean, the problem P1 is properly stated, and the nested design—first place PAs, then solve an SDR for beamforming and AN—is a sensible way to attack a non-convex beast. The paper is honest that the PA placement is suboptimal, and the gains over equispaced PAs and a half-wavelength ULA are consistent with the obvious geometric advantage you get from putting antennas next to the targets.

The soft spot, and it is a load-bearing one, is the rank-one recovery in Sec. III-C. The text says an 'eigenvalue decomposition-based approach' turns V_g into rank-one solutions via principal eigenvectors, with a citation to [13]. That is not a proof. Replacing an optimal V_g with its principal eigenvector changes the user SINR, the eavesdropper SINR, and the sensing values in constraints (17b)-(17d) in an uncontrolled way. No Gaussian randomization, no feasibility check, no rank-one certificate is reported. Since every displayed gain, including the 3-30 dB claims, is obtained after that projection step, the plotted curves may correspond to infeasible points even if the SDR itself is solved correctly. This is the first thing I'd ask the authors to fix.

Secondary issues: Eq. (14) is dimensionally unclear (a row-vector product that the text squares); the numerical results are a single synthetic scenario with no code, no error bars, and no parameter sensitivity; the abstract promises 3 dB while Fig. 2 shows 4 dB at one setting; and the comparison in Fig. 4 sets the proposed system's power budget to the baseline's optimized power, which is a favorable but not unreasonable choice. None of these are fatal on their own.

Verdict: the core idea deserves a serious referee, but not in this form. The rank-one gap must be closed—either by proving the recovery, or by doing Gaussian randomization with feasibility checks and showing the curves only use feasible points. If that is fixed, the paper becomes a solid letter-length contribution to the PA-ISAC literature. As it stands, I'd treat the headline gains as plausible but unverified, and I would not cite them in my own work yet.

Referee Report

2 major / 5 minor

Summary. This letter studies a pinching-antenna (PA)-aided integrated sensing and communication system with secrecy constraints. The base station is connected to N waveguides, each carrying M_t PAs; the system serves G users and senses K eavesdropping targets. The authors propose to (i) place PAs greedily along the waveguides with x-coordinates aligned to user and target positions (Section III-B, Eqs. (14)-(16)), and (ii) given these positions, maximize the minimum target illumination power over beamforming matrices and an artificial-noise covariance subject to per-user minimum SINR, per-eavesdropper maximum SINR, rank-one, PSD, power, and inter-PA distance constraints (P1/P2, Eqs. (13)/(17)). The rank-one constraint is relaxed and the SDP is solved; the paper states that principal eigenvectors are used to recover rank-one solutions. Numerical results in Section IV report a 3-dB illumination-power gain over an equidistant-PA baseline and up to 30 dB over a ULA-based secure ISAC baseline [13].

Significance. If the reported gains are feasible, the work is a useful early demonstration of pinching-antenna systems for secure ISAC. The paper has strengths: a clear signal model, an explicit optimization formulation, comparisons against external baselines [13] and [14], and no apparent fitting of free parameters to reproduce the comparison numbers. It also candidly labels the PA-placement step as suboptimal. However, the central numerical claims rest on two unverified steps: the greedy placement has no optimality gap or robustness analysis, and the rank-one recovery after SDR is asserted without a feasibility guarantee. The most serious issue is the latter, because every plotted gain is computed after the projection step.

major comments (2)

[III-C, P2 (Eq. (17))] The rank-one recovery step is not supported. After relaxing (13c), P2 is solved as an SDP; the text then says that an 'eigenvalue decomposition-based approach' converts {V_g} into rank-one solutions by principal eigenvectors, with reference [13]. Replacing an optimal V_g of rank greater than one by its principal eigenvector changes the user SINR in (17b), the eavesdropper SINR in (17c), and the sensing value in (17d) in an uncontrolled way. No Gaussian randomization, feasibility check, or rank-one certificate is reported. Since Figs. 2-4 plot objective values after this projection, the displayed 3-dB and 30-dB gains may correspond to infeasible or suboptimal points. Please either prove that the SDR solution is rank-one under the stated conditions, or add a recovery procedure with feasibility verification and report the worst-case constraint violation.
[III-B, Eqs. (14)-(16)] The greedy PA-placement rule is heuristic and the paper provides no optimality gap, convergence guarantee, or robustness analysis. All numerical gains are generated with this rule, and the claim that the proposed scheme outperforms the baselines therefore depends on this particular placement heuristic. Since the paper explicitly calls the placement suboptimal, this is not an internal inconsistency, but the numerical claims need support: please add a sensitivity study over target and user geometries and, for small N, a comparison against exhaustive placement to quantify the suboptimality.

minor comments (5)

[III-C, Eq. (17e)] The constraint set in (17e) is written as '(13c)-(13g)', which includes the rank-one constraint (13c) that was just relaxed; this makes P2 non-convex as written. The carried-over constraints should be (13d)-(13g) unless the rank-one constraint is intentionally retained.
[III-B, Eqs. (14)-(15)] The notation in Eq. (14) is ambiguous: x^(n) is defined as a row vector of length (n-1)M_t+G, while H(x^(n)) appears to require the full position vector x. Please clarify how the zero-padded channel vector in (15) is combined with H and what values are used for not-yet-positioned PAs.
[III-C, Eq. (17b)-(17c)] The phrase 'equivalently maintain a target minimal SC' is too strong unless the exact relationship between C_s,lb and the chosen bounds gamma_U,lb and gamma_E,ub is stated; the independent SINR bounds are sufficient but not equivalent to the original secrecy-capacity constraint in general.
[Throughout] Minor typos: 'dentoes' should be 'denotes' in Section II-A, and reference [9] has an extra 'P' in the author list.
[IV, Figs. 2 and 4] Please add legends or specify in the captions the exact parameter settings for the baselines, including the number of antennas, power budgets, and array geometry, so that the comparisons are reproducible.

Circularity Check

0 steps flagged · score 1.0 of 10

No circular derivation: the objective and constraints are stated before the algorithms, baselines are external, and no parameter is fitted to the claimed gains; the main caveats are correctness/feasibility gaps, not circularity.

full rationale

The paper's derivation chain is not circular. The optimization problem P1 (Eq. 13) and its relaxed form P2 (Eq. 17) state the sensing objective and secrecy/power constraints before any algorithm is introduced, and the PA-placement rule in Section III-B (Eqs. 14-16) is an explicitly labeled 'suboptimal' greedy heuristic rather than a fitted quantity. The comparison baselines are external prior systems: the equidistant-PA scheme [14] and the secure ULA-ISAC scheme [13], so the reported 3-dB and 30-dB gains are simulation outcomes against independent benchmarks, not quantities forced by construction. The one mild concern is that the PA positions are placed with knowledge of the same target locations that the sensing metric then evaluates, but Section II.A explicitly states that the targets are 'present, where B, acting as an ISAC transceiver aims at sensing and detecting their presence in the pre-known locations,' so this targeting assumption is disclosed rather than smuggled in. There is no load-bearing self-citation: reference [13] is used as an external baseline and for a standard rank-one recovery step, and it is not authored by the present authors. The most serious weakness is in Section III.C, where the rank-one recovery is asserted as 'an eigenvalue decomposition-based approach' with no feasibility proof; replacing an SDR solution by principal eigenvectors can violate the SINR and sensing constraints in (17b)-(17d). That is an omitted proof and a correctness/robustness gap, not an instance where an output reduces to an input by definition. Similarly, the lack of an optimality gap for the greedy placement is a performance-risk concern, not circularity. Accordingly, the circularity score is 1.

Assumptions & free parameters 4 free parameters · 6 assumptions · 0 invented entities

The proposed design pulls its system model from prior PASS literature and uses a hand-designed placement rule plus SDP. No physical entity is invented. The optimization depends on several unstated or inconsistent simulation parameters, and the optimality of the two algorithmic steps is assumed rather than derived.

free parameters (4)

Delta_x (minimum inter-PA separation)
Required by constraint (13f) and used in line search (16), but omitted from Table I; the chosen value changes which target positions are reachable and the resulting illumination power.
theta (per-PA power ratio)
Assumed equal for all PAs (Section II-A), 0<theta<=1/Mt, but the actual value used in simulations is never reported; it scales all channel gains and thus the absolute dB numbers.
n_g (waveguide refractive index)
Appears in the in-waveguide phase in (6) but is not specified in Table I; it affects the superposition of signals from PAs on each waveguide.
gamma_E,ub (max eavesdropper SINR) = 3 dB in Table I; -6 dB in Fig. 4 caption
A hand-set secrecy constraint that directly shapes the feasible beamforming set and the reported illumination power; inconsistent between sections.

assumptions (6)

domain assumption Channel model of pinching antenna systems in Eqs. (2)-(6), including FSPL and in-waveguide propagation with equal power ratio theta.
Adopted from [4] without derivation or measurement; all numerical claims assume this model.
ad hoc to paper Greedy alignment of PAs with user and target x-coordinates yields a near-optimal placement for the non-convex P1.
Section III-B introduces the rule with no optimality or approximation guarantee; the claimed gains depend on it.
ad hoc to paper The SDR relaxation followed by principal-eigenvector projection yields feasible rank-one beamformers.
Section III-C asserts the recovery step via [13], but no proof is given that SINR constraints and objective are preserved.
ad hoc to paper Secrecy-capacity constraint (13b) is equivalently replaced by independent SINR bounds (17b)-(17c).
The two SINR bounds are sufficient but the equivalence is not proven; the calibration between gamma_U,lb, gamma_E,ub and C_s,lb is never given.
domain assumption All targets are at known locations and behave as passive eavesdroppers with known RCS.
Used in problem formulation and in Figs. 2-4; in practice target positions and RCS are uncertain.
standard math AWGN and zero-mean complex Gaussian artificial noise.
Standard statistical assumptions, no controversy.

how reviews work

0 comments

Cite this review

Pith. "Pith review of Secure Pinching Antenna-aided ISAC." pith.science (2026). https://pith.science/paper/MMW5VDIG

@misc{pith2026250713131,
  author       = {Pith},
  title        = {Pith review of: Secure Pinching Antenna-aided ISAC},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/MMW5VDIG}},
  note         = {Machine review of arXiv:2507.13131}
}

abstract

In this letter, a pinching antenna (PA)-aided scheme for establishing a secure integrated sensing and communication system (ISAC) is investigated. The underlying system comprises a dual-functional radar communication (DFRC) base station (BS) linked to multiple waveguides to serve several downlink users while sensing a set of malicious targets in a given area. The PA-aided BS aims at preserving communication confidentiality with the legitimate users while being able to detect malicious targets. One objective of the proposed scheme is to optimize the PA locations, based on which an optimal design of the legitimate signal beamforming and artificial noise covariance matrices is provided to maximize the network's sensing performance, subject to secrecy and total power constraints. We demonstrate the efficacy of the proposed scheme through numerical examples and compare that against a traditional DFRC ISAC system with a uniform linear array of half-wavelength-spaced antennas. We show that the proposed scheme outperforms the baseline PA-aided scheme with equidistant PAs by $3$ dB in terms of illumination power, while it can provide gains of up to $30$ dB of the same metric against a traditional ISAC system with half-wavelength-space uniform linear arrays.

Figures

Figures reproduced from arXiv: 2507.13131 by the authors.

**Figure 2.** Illumination power of the proposed scheme vs. [PITH_FULL_IMAGE:figures/full_fig_p005_2.png] view at source ↗

**Figure 3.** Illumination power pattern over the considered communication and [PITH_FULL_IMAGE:figures/full_fig_p005_3.png] view at source ↗

Discussion (0). Sign in to comment.

Forward citations

Cited by 1 Pith paper

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

Dual-Waveguide Pinching Antennas for PLS: Parallel Placement or Orthogonal Placement?
eess.SP 2025-10 conditional novelty 5.0 of 10

For dual-waveguide pinching-antenna systems, an FeaPSO/SCA algorithm maximizes secure rate and energy efficiency, and orthogonal waveguide placement offers a modest, scenario-dependent security advantage over parallel...

Reference graph

Works this paper leans on

15 extracted references · 8 canonical work pages · cited by 1 Pith paper

[13]

Secure full duplex integrated sensing and communications,

A. Bazzi and M. Chafii, “Secure full duplex integrated sensing and communications,” IEEE Trans. Inf. Forensics Security, vol. 19, pp. 2082– 2097, 2024

work page 2024
[14]

Array gain for pinching-antenna systems (pass),

C. Ouyang et al. , “Array gain for pinching-antenna systems (pass),” IEEE Commun. Lett. , vol. 29, no. 6, pp. 1471–1475, 2025

work page 2025
[1]

Power allocation for massive MIMO-ISAC systems,

B. Liao et al. , “Power allocation for massive MIMO-ISAC systems,” IEEE Trans. Wireless Commun. , vol. 23, no. 10, pp. 14 232–14 248, 2024

work page 2024
[2]

Massive MIMO: ten myths and one critical ques- tion,

E. Björnson et al. , “Massive MIMO: ten myths and one critical ques- tion,” IEEE Commun. Mag. , vol. 54, no. 2, pp. 114–123, 2016

work page 2016
[3]

Pinching antenna: Using a dielectric waveguide as an antenna,

A. Fukuda et al., “Pinching antenna: Using a dielectric waveguide as an antenna,” NTT DOCOMO Technical J. , vol. 23, no. 3, p. 5–12, 2022

work page 2022
[4]

Flexible-antenna systems: A pinching-antenna perspective,

Z. Ding et al. , “Flexible-antenna systems: A pinching-antenna perspective,” 2024. [Online]. Available: https://arxiv.org/abs/2412.02376

arXiv 2024
[5]

Modeling and beamforming optimization for pinching-antenna systems,

Z. Wang et al. , “Modeling and beamforming optimization for pinching-antenna systems,” 2025. [Online]. Available: https://arxiv.org/abs/2502.05917

arXiv 2025
[6]

Rate Maximization for Downlink Pinching-Antenna Systems

Y . Xu et al. , “Rate maximization for downlink pinching-antenna systems,” 2025. [Online]. Available: https://arxiv.org/abs/2502.12629

work page Pith review arXiv 2025

Show all 15 references

[7]

Downlink beamforming with pinching- antenna assisted MIMO systems,

A. Bereyhi et al. , “Downlink beamforming with pinching- antenna assisted MIMO systems,” 2025. [Online]. Available: https://arxiv.org/abs/2502.01590

2025 arXiv
[8]

Minimum data rate maximization for uplink pinching- antenna systems,

S. Tegos et al., “Minimum data rate maximization for uplink pinching- antenna systems,” IEEE Wireless Commun. Lett. , pp. 1–1, 2025

2025
[9]

Secrecy rate maximization with artificial noise for pinching-antenna systems,

P P. Papanikolaou et al. , “Secrecy rate maximization with artificial noise for pinching-antenna systems,” 2025. [Online]. Available: https://arxiv.org/abs/2504.10656

2025 arXiv
[10]

Pinching-antenna assisted ISAC: A CRLB perspective,

Z. Ding, “Pinching-antenna assisted ISAC: A CRLB perspective,”
[11]

Multi-waveguide pinching antennas for ISAC,

W. Mao et al. , “Multi-waveguide pinching antennas for ISAC,” 2025. [Online]. Available: https://arxiv.org/abs/2505.24307

2025 arXiv
[12]

Integrated sensing and communications for pinching-antenna systems (PASS),

Z. Zhang et al. , “Integrated sensing and communications for pinching-antenna systems (PASS),” 2025. [Online]. Available: https://arxiv.org/abs/2504.07709

2025 arXiv
[2025]

Available: https://arxiv.org/abs/2504.05792

[Online]. Available: https://arxiv.org/abs/2504.05792

arXiv

Pith tools

Reviewed August 6, 2026 · model on record in the stance chip above.

[1] [13]

Secure full duplex integrated sensing and communications,

A. Bazzi and M. Chafii, “Secure full duplex integrated sensing and communications,” IEEE Trans. Inf. Forensics Security, vol. 19, pp. 2082– 2097, 2024

work page 2024

[2] [14]

Array gain for pinching-antenna systems (pass),

C. Ouyang et al. , “Array gain for pinching-antenna systems (pass),” IEEE Commun. Lett. , vol. 29, no. 6, pp. 1471–1475, 2025

work page 2025

[3] [1]

Power allocation for massive MIMO-ISAC systems,

B. Liao et al. , “Power allocation for massive MIMO-ISAC systems,” IEEE Trans. Wireless Commun. , vol. 23, no. 10, pp. 14 232–14 248, 2024

work page 2024

[4] [2]

Massive MIMO: ten myths and one critical ques- tion,

E. Björnson et al. , “Massive MIMO: ten myths and one critical ques- tion,” IEEE Commun. Mag. , vol. 54, no. 2, pp. 114–123, 2016

work page 2016

[5] [3]

Pinching antenna: Using a dielectric waveguide as an antenna,

A. Fukuda et al., “Pinching antenna: Using a dielectric waveguide as an antenna,” NTT DOCOMO Technical J. , vol. 23, no. 3, p. 5–12, 2022

work page 2022

[6] [4]

Flexible-antenna systems: A pinching-antenna perspective,

Z. Ding et al. , “Flexible-antenna systems: A pinching-antenna perspective,” 2024. [Online]. Available: https://arxiv.org/abs/2412.02376

arXiv 2024

[7] [5]

Modeling and beamforming optimization for pinching-antenna systems,

Z. Wang et al. , “Modeling and beamforming optimization for pinching-antenna systems,” 2025. [Online]. Available: https://arxiv.org/abs/2502.05917

arXiv 2025

[8] [6]

Rate Maximization for Downlink Pinching-Antenna Systems

Y . Xu et al. , “Rate maximization for downlink pinching-antenna systems,” 2025. [Online]. Available: https://arxiv.org/abs/2502.12629

work page Pith review arXiv 2025