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REVIEW 2 major objections 2 minor 15 references

Rotatable Antenna Meets Multiple Access: NOMA or OMA?

T0 review · 2 major / 2 minor · reviewed 2026-06-28 · grok-4.3

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Pith's one-line read Rotatable antennas reduce transmit power in multiple access networks, but NOMA can require more power than TDMA when users are symmetrically placed.

desk verdict Simulations show RA cuts power and can make NOMA worse than TDMA in symmetric cases, but the PSO solver leaves those orderings unverified. read the letter →

arxiv 2606.03035 v1 pith:Y5VXJVQQ submitted 2026-06-02 cs.IT cs.SYeess.SYmath.IT

Qi Dai , Beixiong Zheng , Yanhua Tan , Weidong Mei , Jie Tang , Fangjiong Chen This is my paper · ORCID
classification cs.ITcs.SYeess.SYmath.IT
keywords rotatableantennaNOMAOMApowerminimizationmultipleaccessparticleswarmoptimizationtransmitdirectionalgain
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

The paper compares non-orthogonal multiple access against orthogonal schemes such as time division when base-station antennas can rotate to change their directional gain pattern. It minimizes total transmit power while meeting each user's target rate and respecting the antenna's rotation limits. Rotation lowers the required power for both schemes relative to fixed antennas. When users have equal channel conditions, the NOMA version sometimes needs more power than time-division access. The ordering reverses in deployments where users have markedly different channel strengths.

What carries the argument

The rotational angle of the antenna, optimized to minimize total transmit power subject to rate constraints and rotation limits.

What would settle it

An exhaustive search over all feasible rotational angles or a different global solver that produces a lower power value for NOMA than reported, or that shows TDMA no longer uses less power than NOMA in symmetric cases.

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Extended reading notes

Core claim

In RA-assisted communication systems, optimizing the antenna rotation angle via particle swarm optimization allows lower transmit power to satisfy user rate requirements than fixed antennas. For symmetric user deployments, the NOMA scheme may require higher power than TDMA, while in asymmetric deployments NOMA shows better performance in terms of robustness and energy efficiency.

Load-bearing premise

The particle swarm optimization algorithm is assumed to locate a sufficiently good rotational angle that supports the claimed power-minimization performance under the non-convex problem with rotational-range constraints.

Editorial extensions

If this is right

  • RA-assisted schemes achieve lower transmit power than fixed-antenna systems.
  • NOMA can require more power than TDMA when users are symmetrically located.
  • NOMA provides better robustness and energy efficiency than TDMA in asymmetric user scenarios.
  • The performance advantage of NOMA or TDMA depends on the symmetry of user channel conditions.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • System designers could select NOMA or TDMA based on measured user asymmetry rather than defaulting to one scheme.
  • Joint optimization of rotation angle with power allocation might yield further savings beyond the separate treatment used here.
  • Real deployments with hardware rotation limits and imperfect channel knowledge would test whether the simulated ordering holds.
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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

2 major / 2 minor

Summary. The manuscript compares rotatable-antenna (RA) assisted NOMA and OMA (TDMA) schemes for transmit-power minimization subject to rotational-range and per-user rate constraints. A PSO heuristic is used to optimize the antenna rotation angle in the resulting non-convex problem; simulations are reported to show that RA yields substantial power savings relative to fixed-antenna baselines, that RA-NOMA can require more power than TDMA under symmetric user placements, and that RA-NOMA is more robust under asymmetric placements.

Significance. If the reported performance ordering is robust to the choice of optimizer, the work supplies a concrete, deployment-relevant insight: user geometry should influence the choice between NOMA and OMA when rotatable antennas are available. The explicit comparison of the two multiple-access schemes under the same RA hardware constraint is a useful contribution to the emerging RA literature.

major comments (2)
  1. [optimization section / PSO algorithm description] The central performance claims (RA power reduction, NOMA-vs-TDMA ordering in symmetric vs. asymmetric cases) rest exclusively on the solutions returned by the PSO procedure described in the optimization section. Because PSO is a stochastic heuristic without global-optimality guarantees, and because no verification (multiple random restarts, grid search on a discretized angle set, or comparison against an alternative solver) is reported, it is possible that superior rotation angles exist that would alter the reported power values and potentially reverse the NOMA/TDMA ordering. This issue is load-bearing for every quantitative conclusion in the letter.
  2. [simulation results section] No sensitivity analysis or error bars are provided for the PSO runs. Consequently it is impossible to assess whether the observed performance gaps are statistically significant or merely artifacts of particular PSO realizations.
minor comments (2)
  1. [abstract] The abstract states that RA-assisted NOMA “may perform worse than TDMA” in symmetric deployments; the corresponding simulation figure or table should be referenced so readers can immediately locate the supporting data.
  2. [system model] Notation for the rotational angle, the feasible interval, and the channel gains should be introduced once in the system-model section and used consistently thereafter.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive comments on the optimization reliability and simulation analysis. We address each point below and will incorporate the suggested verifications in the revised manuscript.

read point-by-point responses

  1. Referee: [optimization section / PSO algorithm description] The central performance claims (RA power reduction, NOMA-vs-TDMA ordering in symmetric vs. asymmetric cases) rest exclusively on the solutions returned by the PSO procedure described in the optimization section. Because PSO is a stochastic heuristic without global-optimality guarantees, and because no verification (multiple random restarts, grid search on a discretized angle set, or comparison against an alternative solver) is reported, it is possible that superior rotation angles exist that would alter the reported power values and potentially reverse the NOMA/TDMA ordering. This issue is load-bearing for every quantitative conclusion in the letter.

    Authors: We agree that PSO, as a stochastic heuristic, lacks global optimality guarantees and that the absence of verification is a limitation. In the revised version we will add: (i) results from 100 independent PSO runs with varied random seeds, retaining the best objective value per instance; (ii) a grid-search benchmark over a 0.1° discretization of the feasible rotation interval; and (iii) a brief comparison with a derivative-free alternative (e.g., Nelder-Mead) on selected instances. These additions will confirm that the reported power values and the NOMA/TDMA ordering under symmetric versus asymmetric geometries remain consistent. revision: yes

  2. Referee: [simulation results section] No sensitivity analysis or error bars are provided for the PSO runs. Consequently it is impossible to assess whether the observed performance gaps are statistically significant or merely artifacts of particular PSO realizations.

    Authors: We accept this observation. The revised manuscript will include, for every plotted point, the mean and standard deviation of the minimized transmit power obtained across the multiple PSO runs, together with error bars in all figures. This will allow readers to judge the statistical significance of the gaps between RA-NOMA and RA-TDMA. revision: yes

Circularity Check

0 steps flagged · score 0.0 of 10

No circularity in derivation or claims

full rationale

The paper formulates a transmit-power minimization problem under rotational constraints, applies PSO as a numerical solver, and reports simulation outcomes as empirical results. No equations, fitted parameters, or self-citations are shown to reduce the reported performance ordering or power savings to inputs by construction. The comparison between NOMA and TDMA is presented as an observed outcome of the optimization rather than a self-referential prediction.

Assumptions & free parameters 1 free parameters · 1 assumptions · 0 invented entities

Results depend on numerical search rather than closed-form derivation; performance ordering is obtained only after running the optimizer on assumed channel and rate parameters.

free parameters (1)
  • antenna rotational angle
    Chosen by PSO for each scenario to minimize total transmit power subject to rate and range constraints.
assumptions (1)
  • domain assumption Directional gain can be reconfigured continuously within a stated rotational range and the far-field channel model remains valid.
    Invoked implicitly when the optimization treats rotation as the sole spatial degree of freedom.

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Cite this review

Pith. "Pith review of Rotatable Antenna Meets Multiple Access: NOMA or OMA?." pith.science (2026). https://pith.science/paper/Y5VXJVQQ

@misc{pith2026260603035,
  author       = {Pith},
  title        = {Pith review of: Rotatable Antenna Meets Multiple Access: NOMA or OMA?},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/Y5VXJVQQ}},
  note         = {Machine review of arXiv:2606.03035}
}
read the original abstract

Rotatable antenna (RA) technology has emerged as a promising solution to enhance spectrum efficiency by exploiting additional spatial degrees of freedom (DoFs) in multiple access networks. However, the relative performance superiority among different multiple access schemes remains largely unclear due to the unique capability of RA in reconfiguring the directional gain pattern. In this letter, we conduct a theoretical comparison between non-orthogonal multiple access (NOMA) and orthogonal multiple access (OMA) schemes in RA-assisted communication systems in terms of transmit power minimization, subject to constraints on antenna rotational range and users' target rates. To address the associated non-convex optimization problem, a particle swarm optimization (PSO) algorithm is employed to optimize the rotational angle. Simulation results demonstrate that RA-assisted schemes significantly reduce transmit power compared to fixed-antenna benchmarks. Furthermore, RA-assisted NOMA may perform worse than time-division multiple access (TDMA) for symmetric user deployments, while it exhibits superior robustness and energy efficiency in asymmetric scenarios.

Figures

Figures reproduced from arXiv: 2606.03035 by the authors.

Figure 1
Figure 1. An illustration of NOMA and OMA in an RA-assisted comm [PITH_FULL_IMAGE:figures/full_fig_p001_1.png] view at source ↗
Figure 2
Figure 2. Performance comparison of OMA and NOMA in Case 1. [PITH_FULL_IMAGE:figures/full_fig_p005_2.png] view at source ↗

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Reference graph

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