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arxiv: 2604.23246 · v1 · submitted 2026-04-25 · 📡 eess.SP

Recognition: unknown

Leaky-Coaxial Pinching-Antenna System with Adjustable Slot Apertures

Kaidi Wang , Daniel K. C. So , Zhiguo Ding , George K. Karagiannidis
Authors on Pith no claims yet

Pith reviewed 2026-05-08 07:35 UTC · model grok-4.3

classification 📡 eess.SP
keywords leaky coaxial cablepinching antennaadjustable slot aperturessum rate maximizationTDMA optimizationoutage probabilitywireless communication systems
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The pith

Continuous adjustment of slot apertures in leaky-coaxial pinching antennas raises sum rates and lowers outage probabilities over binary activation and fixed systems.

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

The paper proposes modeling slot size variation as continuous amplitude scaling of each slot's induced channel, or equivalently as power coefficients, rather than restricting to binary on/off states. Analytical expressions are derived that quantify the resulting rate gains relative to binary activation and isolate the effect of channel coherence time on those gains. Static and dynamic TDMA resource allocation problems are then posed and solved by combining quadratic transformation, successive convex approximation, and alternating optimization. Simulations establish that the resulting design exceeds the sum rate and outage performance of conventional fixed-antenna deployments, legacy LCX systems, and binary-slot LCX variants.

Core claim

The LCX pinching-antenna system with adjustable slot apertures is proposed, where aperture size is continuously varied and modeled as amplitude scaling of slot channels or power coefficients. Analytical results quantify the performance gain of this continuous adjustment over binary activation and show the role of channel coherence in rate improvement. Sum rate maximization problems for static and dynamic TDMA are formulated and solved efficiently, with simulations showing outperformance against conventional fixed antennas, traditional LCX, and binary schemes in sum rate and outage probability.

What carries the argument

Adjustable slot apertures modeled as continuous power coefficients that scale the amplitudes of the channels induced by individual slots.

If this is right

  • Continuous aperture adjustment yields strictly higher achievable sum rates than binary slot activation once channel coherence is accounted for.
  • The derived analytical rate expressions directly link channel coherence time to the magnitude of the improvement obtained from continuous control.
  • Both static and dynamic TDMA sum-rate problems admit efficient solutions via quadratic transform plus successive convex approximation and alternating updates.
  • The resulting system simultaneously improves sum rate and outage probability relative to fixed-antenna baselines and legacy LCX implementations.

Where Pith is reading between the lines

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

  • The continuous-control model opens the possibility of joint optimization with power allocation across multiple users without requiring additional hardware switches.
  • Because the design targets lower-frequency regimes where distributed radiation is practical, it may reduce the number of base stations needed for reliable coverage in indoor or obstructed settings.
  • Hardware realizations that permit smooth mechanical or electronic slot-size variation would need to preserve the assumed amplitude-only scaling for the predicted gains to materialize.

Load-bearing premise

Aperture adjustment acts as pure amplitude scaling of the slot-induced channels without introducing phase changes, losses, or nonlinear distortions.

What would settle it

A controlled over-the-air measurement that records the achieved sum rate with continuously variable slot sizes versus binary on/off activation under the same user locations and coherence conditions would disprove the claimed gains if the continuous case shows no improvement.

Figures

Figures reproduced from arXiv: 2604.23246 by Daniel K. C. So, George K. Karagiannidis, Kaidi Wang, Zhiguo Ding.

Figure 1
Figure 1. Figure 1: Illustration of the considered downlink LCX Pinchin view at source ↗
Figure 2
Figure 2. Figure 2: An illustration of the symmetric sliding shutter bas view at source ↗
Figure 3
Figure 3. Figure 3: Impact of the transmit power on the sum rate and view at source ↗
Figure 5
Figure 5. Figure 5: Impact of the width of the region on the sum rate and view at source ↗
Figure 6
Figure 6. Figure 6: Impact of the number of users on the sum rate and view at source ↗
read the original abstract

As a practical physical implementation of pinching-antenna systems, leaky coaxial cable (LCX) enables distributed radiation in more general wireless environments, particularly for lower-frequency applications. In this paper, a leaky-coaxial pinching-antenna system, referred to as the LCX pinching-antenna system, is investigated, and adjustable slot apertures are introduced, such that the slot size can be continuously adjusted rather than being restricted to binary activation. Specifically, the aperture adjustment is modeled as amplitude scaling of the channels induced by the corresponding slots, or equivalently, as power coefficients associated with different slots. Accordingly, analytical results are derived to quantify the performance gain of continuous aperture adjustment over binary slot activation and to reveal the impact of channel coherence on the achievable data rate improvement. Furthermore, static and dynamic time-division multiple access (TDMA) schemes are considered, and the corresponding sum rate maximization problems are formulated and efficiently solved by quadratic transform based optimization, combined with successive convex approximation and alternating updates. Simulation results demonstrate that the proposed design can significantly outperform conventional fixed-antenna systems, traditional LCX schemes, and binary slot activation in terms of both achievable sum rate and outage probability.

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 proposes a leaky-coaxial pinching-antenna system (LCX-PAS) with continuously adjustable slot apertures, modeled as amplitude scaling of per-slot channels or equivalent power coefficients. It derives analytical expressions quantifying the performance gain of continuous adjustment over binary slot activation and the role of channel coherence. Sum-rate maximization problems are formulated for static and dynamic TDMA schemes and solved via quadratic transform combined with successive convex approximation (SCA) and alternating updates. Simulations show the design outperforms conventional fixed-antenna systems, traditional LCX schemes, and binary activation in sum rate and outage probability.

Significance. If the amplitude-scaling model holds, the work supplies analytical performance bounds and efficient, reproducible optimization procedures (quadratic transform + SCA + alternating updates) for LCX-based distributed antennas, together with concrete simulation evidence of gains. These elements constitute a clear contribution to practical pinching-antenna implementations at lower frequencies.

major comments (2)
  1. [System Model] System Model (as described in the abstract and subsequent formulation): aperture adjustment is modeled solely as amplitude scaling of the induced channels or as power coefficients. This assumption is load-bearing for every analytical gain derivation and all reported simulation results; the manuscript does not examine whether physical aperture variation also alters phase, radiation pattern, efficiency, or mutual coupling. If those effects are non-negligible, the claimed superiority over binary activation and fixed-antenna baselines becomes an artifact of the simplified model rather than a demonstrated system-level improvement.
  2. [Performance Analysis] Analytical results on performance gain and coherence impact (abstract and performance-analysis section): the derivations assume channel coherence properties allow the continuous-adjustment gains to carry over to the optimized TDMA schedules. No sensitivity analysis or explicit coherence-time versus optimization-overhead trade-off is provided, leaving the translation from analysis to the dynamic-TDMA simulations unverified.
minor comments (2)
  1. [Abstract] The abstract and optimization section would benefit from a single sentence clarifying the distinction between the static and dynamic TDMA formulations and their respective complexity.
  2. [Simulations] Figure captions and simulation-parameter tables should explicitly list the LCX cable parameters and slot-spacing values used, to facilitate reproducibility.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive and insightful comments, which help improve the clarity and rigor of our manuscript. We address each major comment below and indicate the planned revisions.

read point-by-point responses

  1. Referee: [System Model] System Model (as described in the abstract and subsequent formulation): aperture adjustment is modeled solely as amplitude scaling of the induced channels or as power coefficients. This assumption is load-bearing for every analytical gain derivation and all reported simulation results; the manuscript does not examine whether physical aperture variation also alters phase, radiation pattern, efficiency, or mutual coupling. If those effects are non-negligible, the claimed superiority over binary activation and fixed-antenna baselines becomes an artifact of the simplified model rather than a demonstrated system-level improvement.

    Authors: We acknowledge that the continuous aperture adjustment is modeled exclusively via amplitude scaling (or equivalent power coefficients) to enable closed-form analysis and efficient optimization. This choice reflects the primary control mechanism in LCX pinching-antenna implementations at the lower frequencies targeted by the work, where slot-size variation directly modulates radiated power while phase effects can be calibrated or assumed constant in the system design. We agree that a complete electromagnetic characterization would also consider secondary impacts on phase, pattern, efficiency, and coupling; however, incorporating full-wave simulation of these effects lies outside the scope of the present information-theoretic and optimization-focused study. To address the concern, we will add a new subsection in the system model that explicitly states the modeling assumptions, discusses their applicability to practical LCX hardware, and outlines how unmodeled effects could be incorporated in future extensions. revision: partial

  2. Referee: [Performance Analysis] Analytical results on performance gain and coherence impact (abstract and performance-analysis section): the derivations assume channel coherence properties allow the continuous-adjustment gains to carry over to the optimized TDMA schedules. No sensitivity analysis or explicit coherence-time versus optimization-overhead trade-off is provided, leaving the translation from analysis to the dynamic-TDMA simulations unverified.

    Authors: The analytical performance-gain expressions and the dynamic-TDMA formulation indeed rest on the premise that channel realizations remain constant over the interval required for CSI acquisition, optimization, and data transmission. The dynamic-TDMA simulations apply the quadratic-transform solution once per coherence block under perfect instantaneous CSI. We concur that an explicit sensitivity study relating coherence time to optimization overhead would strengthen the practical relevance of these results. Accordingly, we will revise the performance-analysis and simulation sections to include additional numerical results that vary the ratio of coherence time to optimization duration and quantify the resulting degradation in sum-rate gains, thereby verifying the conditions under which the reported advantages persist. revision: yes

Circularity Check

0 steps flagged

No significant circularity; derivation self-contained within explicit modeling assumptions

full rationale

The paper explicitly adopts the modeling choice that continuous aperture adjustment equals amplitude scaling (or power coefficients) of per-slot channels, then derives analytical performance gains and solves sum-rate maximization problems under that model using standard techniques (quadratic transform, SCA, alternating optimization). Simulations are performed consistently within the same model. No steps reduce predictions to inputs by construction, no load-bearing self-citations, no fitted parameters renamed as predictions, and no uniqueness theorems or ansatzes smuggled via prior work. The central claims are scoped to the assumed channel model and are not tautological with the inputs.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The central claims rest on standard wireless channel models and optimization assumptions rather than new postulates; no invented physical entities.

axioms (2)
  • domain assumption Wireless channels exhibit coherence properties that affect achievable rate improvement from continuous adjustment
    Invoked to derive analytical performance gains in the abstract.
  • domain assumption Perfect or known channel state information is available for TDMA optimization
    Required for formulating and solving the sum-rate maximization problems.

pith-pipeline@v0.9.0 · 5514 in / 1382 out tokens · 42214 ms · 2026-05-08T07:35:09.105625+00:00 · methodology

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Reference graph

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