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REVIEW 3 major objections 6 minor 2 cited by

A single waveguide with M center-fed ports supports up to M independent spatial streams.

Reviewed by Pith at T0; open to challenge. T0 means a machine referee read the full paper against a public rubric. the ladder, T0–T4 →

T0 review · deepseek-v4-flash

2026-08-02 23:03 UTC pith:HXHBLVGR

load-bearing objection Real extension of C-PASS with plausible DoF scaling, but the proof of the headline theorem has a gap and the power-scaling validation is overclean. the 3 major comments →

arxiv 2602.14805 v2 pith:HXHBLVGR submitted 2026-02-16 cs.IT math.IT

Center-Fed Pinching Antenna System (C-PASS): Modeling, Analysis, and Beamforming Design

classification cs.IT math.IT MSC 94A1594A05
keywords center-fed pinching antenna systemdegree of freedompower scaling lawbeamforming designMIMOwaveguideWMMSE6G
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved

The pith

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

The paper proposes a generalized center-fed pinching antenna system (C-PASS) in which a single dielectric waveguide is fed at M distributed input ports, splitting each signal into a forward and a backward wave. It claims that under a symmetric configuration (equal power splitting and half radiation per antenna), the achievable degrees of freedom are min{M, K}, where K is the number of receive antennas, and the received power scales as O(P_T M). This breaks the rank-one bottleneck of conventional end-fed pinching-antenna systems and the DoF=2 ceiling of earlier centrally-fed designs, enabling spatial multiplexing without deploying multiple waveguides. The paper also develops an alternating beamforming algorithm that jointly optimizes transmit precoding, power splitting ratios, antenna positions, and radiation coefficients, and reports that a single-waveguide C-PASS can outperform a multi-waveguide PASS by more than 10 dB in high-attenuation regimes.

Core claim

The central claim is that the effective channel from the M input ports to K users, H_eff = H Q^T, has rank min{M, K} under symmetric power splitting (beta_F = beta_B = 1/2) and per-antenna radiation ratio delta = 1/2. The in-waveguide matrix Q is full column rank because the distributed feeding creates a Toeplitz-like structure with nonzero determinant, and after an invertible transformation T_Q the effective channel reduces to the first M columns of an invertible matrix. The paper proves this via determinant computation of Q_0 and rank factorization, and derives the received power scaling O(P_T M) by bounding the coherent sum of bidirectional propagation paths. Consequently, a single wavegu

What carries the argument

The engine is the in-waveguide matrix Q in (10), whose entries combine power-splitting ratios beta, per-antenna radiation coefficients delta, in-waveguide attenuation and phase, and the geometric distances between input ports and pinching antennas. With uniformly spaced ports and symmetric splitting, Q takes a banded Toeplitz form with element powers of a single complex number w; its principal M x M minor has determinant proportional to (1-w)^{M-1} w^M, which is nonzero. This full-rank Q is what lifts H_eff to rank min{M,K}. The power-scaling bound then exploits the fact that the M ports each add a coherent contribution, giving O(M) power gain.

Load-bearing premise

The DoF proof assumes the user-to-antenna channel H is full rank and then asserts that the first M columns of the transformed matrix H T_Q^{-1} also have full rank; this submatrix rank condition is not proved and requires a generic-position argument that holds for random user locations but not for every geometry.

What would settle it

For a fixed symmetric configuration, place K users at symmetric positions (equal distances or collinear with the waveguide), compute H_eff = H Q^T numerically, and check whether rank(H_eff) < min{M,K}; if yes for any configuration, the theorem as stated is false. Also, measure received power versus M in a high-attenuation waveguide (alpha=0.2095) and see if the slope in dB approaches 10 log10(M).

Watch this falsifier — get emailed when new claim-graph text bears on it.

If this is right

  • A single waveguide with M input ports can support M simultaneous users or data streams in the high-SNR regime, matching the multiplexing capability of M separate waveguides.
  • Increasing the number of input ports M yields a linear power gain, so adding ports is a more energy-efficient route to higher sum rate than increasing transmit power.
  • In high in-waveguide attenuation, the center-fed design's shorter effective propagation paths let it outperform a multi-waveguide PASS by more than 10 dB.
  • The proposed alternating optimization algorithm monotonically converges to a stationary point, making the joint transmit and pinching beamforming design tractable.
  • The conventional end-fed PASS emerges as a special case (beta_F=1, beta_B=0), so the C-PASS performance is at least as good as that baseline.

Where Pith is reading between the lines

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

  • The DoF=min{M,K} result likely extends multiplicatively to G waveguides, giving M*G spatial streams, a direction the paper itself points to in its conclusion.
  • Because the proof's final rank step requires a generic-position assumption on user locations, adversarial placements such as all users collinear or at equal distances could make H_eff rank-deficient; the claim should be read as holding for almost all random geometries.
  • A practical design rule follows from the numerical robustness: fixed equal power splitting (beta=1/2) loses little performance, so simple passive splitters can be used while transmit precoding absorbs the residual channel variation.
  • The same bidirectional-feeding principle should improve angular resolution in wireless sensing, although the paper does not quantify that benefit.

Editorial analysis

A structured set of objections, weighed in public.

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

Referee Report

3 major / 6 minor

Summary. The paper proposes a generalized center-fed pinching-antenna system (C-PASS) in which a single dielectric waveguide is fed at M distributed input ports with controllable power splitters, generating forward and backward propagating signals. The authors derive closed-form expressions for the achievable DoF and received-power scaling law, claiming DoF = min{M,K} and power gain O(P_T M). They then formulate a sum-rate maximization problem for the joint design of transmit precoding, power splitting ratios, PA positions, and radiation coefficients, and solve it by an alternating WMMSE/BCD algorithm. Numerical simulations are used to validate the scaling laws and to show that the single-waveguide C-PASS can outperform a multi-waveguide end-fed PASS in high-attenuation regimes.

Significance. If the claims are fully established, the paper makes a substantial contribution: it breaks the rank-one DoF bottleneck of conventional single-waveguide PASS without deploying multiple waveguides, and it provides a tractable optimization framework. The paper is also careful in providing closed-form updates for several subproblems and in including numerical verification of the claimed scaling laws. The DoF and power-scaling results are derived from the stated channel model rather than fitted, and the paper explicitly connects its distributed feeding topology to the earlier centralized C-PASS with DoF=2. The main concerns are technical gaps in the proofs of Theorems 1 and 2, not in the overall plausibility of the architecture.

major comments (3)
  1. [Section III-A, Eq. (12)] The definition DoF = lim_{P_T→∞} C/(P_T/N_0) is not the standard DoF and is analytically inconsistent with the rest of the paper. Since C ~ d log_2(P_T/N_0) for a rank-d channel, the quotient tends to 0. The intended definition is presumably DoF = lim_{P_T→∞} C/log_2(P_T/N_0), which is also what Fig. 3 actually measures. Please correct Eq. (12) and any related statements.
  2. [Appendix A, Eqs. (47)-(51)] The key step from rank(\tilde H) = min{M+1,K} to rank([\tilde H]_{:,1:M}) = min{M,K} does not follow. A full-rank matrix can have a rank-deficient submatrix of selected columns; the invertible transformation T_Q^{-1} does not preserve the rank of arbitrary column subsets. The proof needs a generic-position argument: for the LoS channel H with random user positions, det([H T_Q^{-1}]_{:,1:M}) is a nonzero analytic function of the user coordinates when K≥M (and the analogous row condition when K<M), so it is nonzero almost surely. Without this, Theorem 1 only establishes an upper bound rank(H_eff) ≤ min{M,K}.
  3. [Section III-B, Theorem 2 and Appendix B] The proof of the O(P_T M) power scaling law assumes that micro-adjusting PA positions can align the phases of all terms in Eq. (13), so that the upper bound in Eq. (14) is attainable. No feasibility proof is given. The feasible interval is introduced only later as |X_m - X^{PA,init}_m| ≤ Δ, Eq. (39b), and each PA displacement affects many phase terms simultaneously, through both h_n and g_{m,n}. The proof simply drops the complex exponentials. Please state explicit conditions on Δ (or on the user region) under which simultaneous phase alignment is possible, or replace Theorem 2 with a more careful asymptotic statement.
minor comments (6)
  1. [Appendix A] In the sentence before Eq. (48), "determination value" should be "determinant."
  2. [Eq. (4b)] The subscript in the last factor, δ_{n_{m'}}, appears to be a typo; it should likely be δ_{n_{m''}} to match the backward-propagating PA index.
  3. [Section V-A, Baseline 2] The expression X_m^{IN} = 5/4 2π/λ_g is unclear and the formatting is broken; please clarify the exact coordinate formula.
  4. [Eq. (13)] The notation P_T is used inconsistently as "PT" in several places; please unify.
  5. [Section IV-F] The overall complexity expression is difficult to parse due to missing parentheses and line breaks; please restructure it for readability.
  6. [Section II-A] The text after Eq. (4) refers to "remaining power from the m-th input port to the r-th region" but the formal definitions of the sets N^F_{m,r} and N^B_{m,r} would benefit from a short example, since the asymmetric forward/backward indexing is central to the model.

Circularity Check

0 steps flagged

No significant circularity: the claimed DoF and power-scaling laws follow from the stated channel model, with self-citations used only as background/proof template.

full rationale

I walked the derivation chain from the C-PASS signal model in Section II through Theorems 1 and 2. Theorem 1 is proved in Appendix A from the explicit symmetric configuration β_F=β_B=δ=1/2: the paper states rank(H)=min{K,M+1}, computes det(Q_0) in (48) to show Q^T has full column rank, and then concludes rank(H_eff)=min{M,K}. The final inference—that a full-rank transformed matrix has full-rank first M columns—is a genuine proof gap that needs a generic-position argument, but it is not a circular reduction: no equation is re-identified with its input, and no fitted parameter is used to force the rank conclusion. Theorem 2 is likewise derived from the closed-form received power expression (13), the phase-alignment upper bound (14), and the asymptotic calculation in Appendix B; the O(P_T M) law is an implication of the bound, not a target fitted from simulations. The numerical sections validate the formulas by simulating the same model and comparing with the derived expressions and with external baseline architectures; this is self-contained model-based verification rather than fitting-to-target. The paper cites the authors' prior C-PASS work [24] for the starting signal model and for the standard equivalence DoF=rank(H_eff), and [25] for prior DoF=2 context. Those citations are not load-bearing for the new min{M,K} result: the equivalence is independently derivable from Eq. (11), and the prior DoF=2 result is used only as motivation. No uniqueness theorem is imported from the authors, and no ansatz is smuggled in via citation beyond the explicitly stated symmetric configuration. I therefore find no circular step meeting the quoted-reduction standard.

Axiom & Free-Parameter Ledger

2 free parameters · 5 axioms · 1 invented entities

The scaling results are derived under a symmetric configuration (β=δ=1/2) and rest on ideal in-waveguide and free-space LoS models, plus a generic full-rank assumption on user channels. No parameters are fitted to the claimed DoF or power-scaling results; the theory is self-contained given these model axioms.

free parameters (2)
  • Symmetric power splitting and radiation ratios βF=βB=δ=1/2 = 1/2
    Hand-chosen symmetric configuration in Section III-A under which Theorems 1 and 2 are proven. The rank proof and power-scaling bound rely on this value; it is not fitted to data.
  • PA micro-adjustment range Δ = 0.01 m
    Simulation constraint for PA position optimization (Section V-A). Not part of the theoretical scaling law, but used to argue the O(P_T M) law is achievable in practice.
axioms (5)
  • domain assumption In-waveguide propagation follows g = exp(-(α_g + jk_g)d)
    Eq. (5a), Section II-A. Assumes single-mode uniform attenuation and phase along the waveguide, neglecting reflections and mode dispersion.
  • domain assumption Free-space PA-to-user channel is pure LoS with h_{k,n} = η exp(-jk_0 d)/d
    Eq. (5b). Assumes no multipath, blockage, or near-field effects; all users are in the far field of each PA.
  • domain assumption Coupled-mode power radiation: a PA radiates sqrt(δ_n)x and transmits sqrt(1-δ_n)x
    Eqs. (4) and (8), borrowed from [14]. Assumes ideal power splitting at each pinching element and no inter-PA coupling.
  • domain assumption User-PA channel matrix H is full rank, rank(H)=min{K, M+1}
    Appendix A. Requires random user positions in general position. The proof additionally assumes that after invertible transformation, the first M columns of ˜H are full rank, which is not shown.
  • standard math DoF of the channel equals rank(H_eff)
    Appendix A, Eq. (46), following [24]. Standard high-SNR MIMO result for fixed channels; the displayed definition in Eq. (12) is dimensionally inconsistent.
invented entities (1)
  • Distributed center-fed multi-port C-PASS (input ports spaced along a single waveguide with controllable power splitters) no independent evidence
    purpose: Create multiple spatial channels within a single waveguide so that DoF scales linearly with the number of input ports M
    Architecture introduced conceptually (Fig. 1) and analyzed only through simulation in this paper. No prototype, measurement, or external experimental validation is provided.

pith-pipeline@v1.3.0-alltime-deepseek · 42 in / 14881 out tokens · 135538 ms · 2026-08-02T23:03:55.019072+00:00 · methodology

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read the original abstract

A generalized framework for the novel center-fed pinching antenna system (C-PASS) is proposed. Within this framework, closed-form expressions for the degree of freedom (DoF) and power scaling law of the proposed C-PASS are first derived. These theoretical results reveal that the achievable DoF scales linearly with the number of input ports, $M$, and the number of receive antennas, $K$. Furthermore, the derived power scaling laws demonstrate that the C-PASS achieves a power gain of order $\mathcal{O}(P_T M)$, where $P_T$ denotes the transmit power. Based on the proposed C-PASS modeling, a sum-rate maximization problem for the joint optimization of transmit and pinching beamforming is then formulated. To solve this highly coupled non-convex problem, an efficient alternating optimization algorithm is developed. More particularly, the transmit precoding and power splitting ratios are updated via derived closed-form solutions, while the pinching antenna positions and radiation coefficients are optimized using block coordinate descent (BCD) methods. Finally, our numerical results reveal that the single-waveguide C-PASS: 1) achieves superior DoF and power scaling laws compared to the single-waveguide PASS; and 2) outperforms the multi-waveguide PASS in high-attenuation regimes, yielding a substantial gain exceeding $10$ dB.

Figures

Figures reproduced from arXiv: 2602.14805 by Xu Gan, Yuanwei Liu.

Figure 1
Figure 1. Figure 1: Illustration of a C-PASS architecture. • We provide comprehensive numerical results to validate the performance advantages of C-PASS and the effective￾ness of the proposed algorithm. The results demonstrate that: 1) the C-PASS significantly enhance the DoF and power scaling law compared to the conventional PASS; 2) For multi-user communications, single-waveguide C￾PASS can even outperform multi-waveguide P… view at source ↗
Figure 2
Figure 2. Figure 2: Illustration of a C-PASS aided communications. [PITH_FULL_IMAGE:figures/full_fig_p004_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: DoF characterization of C-PASS. precoding is designed via the MRT strategy. Conse￾quently, only the PA positions are refined by applying the proposed Algorithm 1. • Baseline 2 (Conventional Single-Waveguide End-Fed PASS): This baseline represents the traditional configura￾tion where M input ports are co-located at the waveguide terminal to feed signals. The PAs are still uniformly distributed along the wav… view at source ↗
Figure 5
Figure 5. Figure 5: Convergence behavior of the proposed algorithm. [PITH_FULL_IMAGE:figures/full_fig_p010_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: Comparison with transmit-beamforming baselines. [PITH_FULL_IMAGE:figures/full_fig_p010_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: Comparison with pinching-beamforming baselines. [PITH_FULL_IMAGE:figures/full_fig_p011_7.png] view at source ↗
Figure 8
Figure 8. Figure 8: Comparison with conventional PASS architectures. [PITH_FULL_IMAGE:figures/full_fig_p011_8.png] view at source ↗

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Forward citations

Cited by 2 Pith papers

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

  1. Center-Fed Pinching Antenna System for Uplink Environment Sensing

    cs.IT 2026-06 unverdicted novelty 6.0

    Center-fed pinching antenna system achieves strictly lower Ziv-Zakai bound on mean-squared reconstruction error than end-fed PASS for uplink environment sensing via doubled degrees of freedom and closed-form feed-poin...

  2. Access Protocols for Segmented Waveguide-Enabled Pinching-Antenna Systems (SWANs)

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    A two-stage framework recasts high-dimensional channel acquisition as geometric localization and constructs oracle-guided access codebooks under OS, SA, and SM modes to improve uplink random access in SWANs.

Reference graph

Works this paper leans on

33 extracted references · 8 linked inside Pith · cited by 2 Pith papers

  1. [1]

    A vision of 6G wireless systems: Applications, trends, technologies, and open research problems,

    W. Saad, M. Bennis, and M. Chen, “A vision of 6G wireless systems: Applications, trends, technologies, and open research problems,”IEEE Netw., vol. 34, no. 3, pp. 134–142, 2019

  2. [2]

    6G and beyond: The future of wireless communications systems,

    I. F. Akyildiz, A. Kak, and S. Nie, “6G and beyond: The future of wireless communications systems,”IEEE Access, vol. 8, pp. 133 995– 134 030, 2020

  3. [3]

    Pinching-antenna systems: Architecture designs, opportunities, and outlook,

    Y . Liu, Z. Wang, X. Mu, C. Ouyang, X. Xu, and Z. Ding, “Pinching-antenna systems: Architecture designs, opportunities, and outlook,”IEEE Commun. Mag., early access, 2025, doi: 10.1109/MCOM.001.2500037

  4. [4]

    Pinching-antenna systems (PASS): A tutorial,

    Y . Liu, H. Jiang, X. Xu, Z. Wang, J. Guo, C. Ouyang, X. Mu, Z. Ding, A. Nallanathan, G. K. Karagiannidiset al., “Pinching-antenna systems (PASS): A tutorial,”arXiv preprint arXiv:2508.07572, 2025

  5. [5]

    A survey of pinching-antenna systems (PASS),

    Y . Liu, H. Jiang, X. Gan, X. Xu, J. Guo, Z. Wang, C. Ouyang, X. Mu, Z. Ding, A. Nallanathanet al., “A survey of pinching-antenna systems (PASS),”arXiv preprint arXiv:2601.18927, 2026

  6. [6]

    Performance analysis of pinching- antenna systems,

    D. Tyrovolas, S. A. Tegos, P. D. Diamantoulakis, S. Ioannidis, C. K. Liaskos, and G. K. Karagiannidis, “Performance analysis of pinching- antenna systems,”IEEE Trans. Cogn. Commun. Netw., early access, 2025, doi: 10.1109/TCCN.2025.3564470

  7. [7]

    Pinching-antenna sys- tem design with LoS blockage: Does in-waveguide attenuation matter?

    Y . Xu, Z. Ding, O. A. Dobre, and T.-H. Chang, “Pinching-antenna sys- tem design with LoS blockage: Does in-waveguide attenuation matter?” arXiv preprint arXiv:2508.07131, 2025

  8. [8]

    Capacity character- ization of pinching-antenna systems,

    C. Ouyang, Z. Wang, Y . Liu, H. Shin, and Z. Ding, “Capacity character- ization of pinching-antenna systems,”IEEE Trans. Wireless Commun., vol. 25, pp. 10 387–10 404, 2026

  9. [9]

    Pinching antennas in blockage-aware environments: Modeling, design, and optimization,

    X. Xie, F. Fang, Z. Ding, and X. Wang, “Pinching antennas in blockage-aware environments: Modeling, design, and optimization,” arXiv preprint arXiv:2601.01277, 2026

  10. [10]

    Pinching antennas: Principles, applica- tions and challenges,

    Z. Yang, N. Wang, Y . Sun, Z. Ding, R. Schober, G. K. Karagiannidis, V . W. Wong, and O. A. Dobre, “Pinching antennas: Principles, applica- tions and challenges,”IEEE Wireless Commun., early access, 2025, doi: 10.1109/MWC.2025.3607867

  11. [11]

    Exploiting pinching-antenna systems in multicast communications,

    S. Shan, C. Ouyang, Y . Li, and Y . Liu, “Exploiting pinching-antenna systems in multicast communications,”IEEE Trans. Commun., early access, 2025, doi: 10.1109/TCOMM.2025.3626012

  12. [12]

    Channel estimation for pinching-antenna systems (PASS),

    J. Xiao, J. Wang, and Y . Liu, “Channel estimation for pinching-antenna systems (PASS),”IEEE Commun. Lett., vol. 29, no. 8, pp. 1789–1793, 2025

  13. [13]

    Wireless sensing via pinching-antenna systems,

    Z. Wang, C. Ouyang, Y . Liu, and A. Nallanathan, “Wireless sensing via pinching-antenna systems,”arXiv preprint arXiv:2505.15430, 2025

  14. [14]

    Modeling and beamforming optimization for pinching-antenna systems,

    Z. Wang, C. Ouyang, X. Mu, Y . Liu, and Z. Ding, “Modeling and beamforming optimization for pinching-antenna systems,”IEEE Trans. Commun., early access, 2025, doi: 10.1109/TCOMM.2025.3621049

  15. [15]

    MIMO- PASS: Uplink and downlink transmission via MIMO pinching-antenna systems,

    A. Bereyhi, C. Ouyang, S. Asaad, Z. Ding, and H. V . Poor, “MIMO- PASS: Uplink and downlink transmission via MIMO pinching-antenna systems,”arXiv preprint arXiv:2503.03117, 2025

  16. [16]

    Pinching-antenna systems-enabled multi-user communications: Transmission structures and beamforming optimization,

    J. Zhao, H. Song, X. Mu, K. Cai, Y . Zhu, and Y . Liu, “Pinching-antenna systems-enabled multi-user communications: Transmission structures and beamforming optimization,”IEEE Trans. Commun., 2025

  17. [17]

    MIMO pinching- antenna-aided SWIPT,

    H. Li, Z. Lyu, Y . Gao, M. Xiao, and H. V . Poor, “MIMO pinching- antenna-aided SWIPT,”arXiv preprint arXiv:2506.06754, 2025

  18. [18]

    Physical layer security with artificial noise in MIMO pinching-antenna systems,

    P. P. Papanikolaou, D. Bozanis, S. A. Tegos, P. D. Diamantoulakis, P. Sarigiannidis, and G. K. Karagiannidis, “Physical layer security with artificial noise in MIMO pinching-antenna systems,”arXiv preprint arXiv:2511.23079, 2025

  19. [19]

    Joint transmit and pinching beamforming design for pinching antenna- assisted symbiotic radio,

    Z. Wang, G. Zhang, H. Xu, W. Liu, M. Zeng, F. Fang, and D. Niyato, “Joint transmit and pinching beamforming design for pinching antenna- assisted symbiotic radio,”arXiv preprint arXiv:2508.07002, 2025

  20. [20]

    Waveguide division multiple access for pinching-antenna systems (PASS),

    J. Zhao, X. Mu, K. Cai, Y . Zhu, and Y . Liu, “Waveguide division multiple access for pinching-antenna systems (PASS),”arXiv preprint arXiv:2502.17781, 2025

  21. [21]

    Uplink and downlink communications in segmented waveguide-enabled pinching- antenna systems (SW ANs),

    C. Ouyang, H. Jiang, Z. Wang, Y . Liu, and Z. Ding, “Uplink and downlink communications in segmented waveguide-enabled pinching- antenna systems (SW ANs),”IEEE Trans. Commun., vol. 74, pp. 3688– 3703, 2026

  22. [22]

    Segmented waveguide-enabled pinching-antenna systems (SW ANs) for ISAC,

    H. Jiang, C. Ouyang, Z. Wang, Y . Liu, A. Nallanathan, Z. Ding, and R. Schober, “Segmented waveguide-enabled pinching-antenna systems (SW ANs) for ISAC,”arXiv preprint arXiv:2512.07649, 2025

  23. [23]

    Revealing computation- communication trade-off in segmented pinching antenna system (PASS),

    D. Gan, X. Xu, X. Ge, and Y . Liu, “Revealing computation- communication trade-off in segmented pinching antenna system (PASS),”arXiv preprint arXiv:2511.16327, 2025

  24. [24]

    C-PASS: Center-fed pinching antenna system,

    X. Gan and Y . Liu, “C-PASS: Center-fed pinching antenna system,” arXiv preprint arXiv:2512.12619, 2025

  25. [25]

    Center-fed pinching antenna system (C-PASS) aided wireless communications,

    ——, “Center-fed pinching antenna system (C-PASS) aided wireless communications,”arXiv preprint arXiv:2601.07424, 2026

  26. [26]

    D. K. Chenget al.,Field and wave electromagnetics. Pearson Education India, 1989

  27. [27]

    An iteratively weighted MMSE approach to distributed sum-utility maximization for a MIMO interfering broadcast channel,

    Q. Shi, M. Razaviyayn, Z.-Q. Luo, and C. He, “An iteratively weighted MMSE approach to distributed sum-utility maximization for a MIMO interfering broadcast channel,”IEEE Trans. Signal Process., vol. 59, no. 9, pp. 4331–4340, 2011

  28. [28]

    Numerical optimization,

    J. Nocedal, “Numerical optimization,”Springer Ser . Oper . Res. Financ. Eng./Springer, 2006

  29. [29]

    R. P. Brent,Algorithms for minimization without derivatives. Courier Corporation, 2013

  30. [30]

    Vehicular communications over OFDM radar sensing in the 77 GHz mmwave band,

    K. S. A. Dapa, G. Point, S. Bensator, and F. E. Boukour, “Vehicular communications over OFDM radar sensing in the 77 GHz mmwave band,”IEEE Access, vol. 11, pp. 4821–4829, 2023

  31. [31]

    Pinching-antenna systems with in-waveguide attenuation: Performance analysis and algorithm design,

    Y . Xu, Z. Ding, R. Schober, and T.-H. Chang, “Pinching-antenna systems with in-waveguide attenuation: Performance analysis and algorithm design,”arXiv preprint arXiv:2506.23966, 2025

  32. [32]

    Flexible-antenna systems: A pinching-antenna perspective,

    Z. Ding, R. Schober, and H. V . Poor, “Flexible-antenna systems: A pinching-antenna perspective,”IEEE Trans. Commun., early access, 2025, doi: 10.1109/TCOMM.2025.3555866

  33. [33]

    Experimental characterization of bending effects for solid and hollow dielectric waveguides at V-band,

    T.-L. Vu, S. Barlerin, Y . Stricot, R. Sauleau, M. Ettorre, and D. González-Ovejero, “Experimental characterization of bending effects for solid and hollow dielectric waveguides at V-band,”Sci. Rep., vol. 11, no. 1, p. 20679, 2021