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Pinching-antenna-enabled Federated Learning: Tail Latency, Participation, and Convergence Analysis

Yushen Lin, Zihan Chen, Zhiguo Ding

TL;DR

This paper investigates the pinching-antenna system (PASS), which dynamically'pinches'the radiator along a dielectric waveguide to shorten the worst links, and proves that pinching raises the minimum inclusion probability, thus shrinking both the sampling variability and compression-induced floors in a Lyapunov analysis.

Abstract

Federated learning (FL) in wireless networks is limited by straggler delays from unpredictable channel conditions. In this paper, we investigate the pinching-antenna system (PASS), which dynamically 'pinches' the radiator along a dielectric waveguide to shorten the worst links. In synchronous FL (SFL), we prove that PASS shortens the worst-link distance, and it increases the on-time completion probability in asynchronous FL (AFL). Accordingly, SFL exhibits stochastic dominance on round time, while AFL yields explicit latency and participation gains. We then pair physical-layer (PHY)-aware sampling with error-feedback compression and prove that pinching raises the minimum inclusion probability, thus shrinking both the sampling variability and compression-induced floors in a Lyapunov analysis. Simulations demonstrate consistent wall clock speedups and markedly shorter latency tails. By addressing stragglers at their PHY root, PASS complements higher-layer scheduling and accelerates wireless FL in both SFL and AFL.

Pinching-antenna-enabled Federated Learning: Tail Latency, Participation, and Convergence Analysis

TL;DR

This paper investigates the pinching-antenna system (PASS), which dynamically'pinches'the radiator along a dielectric waveguide to shorten the worst links, and proves that pinching raises the minimum inclusion probability, thus shrinking both the sampling variability and compression-induced floors in a Lyapunov analysis.

Abstract

Federated learning (FL) in wireless networks is limited by straggler delays from unpredictable channel conditions. In this paper, we investigate the pinching-antenna system (PASS), which dynamically 'pinches' the radiator along a dielectric waveguide to shorten the worst links. In synchronous FL (SFL), we prove that PASS shortens the worst-link distance, and it increases the on-time completion probability in asynchronous FL (AFL). Accordingly, SFL exhibits stochastic dominance on round time, while AFL yields explicit latency and participation gains. We then pair physical-layer (PHY)-aware sampling with error-feedback compression and prove that pinching raises the minimum inclusion probability, thus shrinking both the sampling variability and compression-induced floors in a Lyapunov analysis. Simulations demonstrate consistent wall clock speedups and markedly shorter latency tails. By addressing stragglers at their PHY root, PASS complements higher-layer scheduling and accelerates wireless FL in both SFL and AFL.
Paper Structure (38 sections, 8 theorems, 103 equations, 8 figures)

This paper contains 38 sections, 8 theorems, 103 equations, 8 figures.

Table of Contents

  1. Introduction
  2. Related Work
  3. Recent Developments in PASS
  4. FL in Wireless Networks
  5. Using Pinching Antenna in FL
  6. System Model
  7. FL Setup
  8. Conventional Antenna: Straggler Distance Analysis
  9. PA: Bottleneck Distance via $m$-Spacings
  10. Latency Advantages of Pinching Antennas
  11. SFL latency: PA dominates at all SNRs
  12. AFL latency: strictly positive PA gain with an explicit SNR threshold
  13. PA Yields More Participants under a Global Deadline
  14. Uniform corridor: closed form and near‑threshold law
  15. Impact of user distribution: stochastic dominance
  16. ...and 23 more sections

Key Result

Proposition 1

Let $m:=M-1\ge1$. Since each $m$-span is a sum of $m$ positive spacings, $\widetilde{L}_M \ge m\min_{1\le j\le K+1}G_j$. Consequently,

Figures (8)

  • Figure 1: (a) SFL—PA centered on the tightest window; (b) AFL—PA over the user.
  • Figure 2: PA stochastically dominates $\mathrm{CONV}$ across thresholds: the PA complementary CDF (CCDF) lies strictly left/below $\mathrm{CONV}$ for all $T$.
  • Figure 3: Normalized participation advantage $N_{\rm PA}-N_{\rm CONV})/K$ vs. deadline $T_d$.
  • Figure 4: CCDF $\Pr[T>t]$ under $\mathrm{CONV}$ and PASS with $D=10$ m, $d=3$ m and $W=1$ MHz. PASS shifts the distribution left and steepens the right tail in both SFL and AFL.
  • Figure 5: Test accuracy versus wall-clock time under $\mathrm{CONV}$ and PASS. PASS shortens links and per-event/round latency, yielding faster wall-clock convergence in both SFL and AFL.
  • ...and 3 more figures

Theorems & Definitions (15)

  • Remark 1
  • Proposition 1: PA lower bound via the minimum simple spacing
  • Remark 2
  • Theorem 1
  • Remark 3
  • Theorem 2
  • proof
  • Proposition 2
  • proof
  • Remark 4
  • ...and 5 more