OFDMA for Pinching Antenna Systems

TL;DR

This paper proposes an OFDMA-based framework for pinching-antenna systems to mitigate inter-symbol interference caused by frequency selectivity, improving user fairness and minimum data rates in mmWave communication scenarios.

Contribution

It models the channel as an FIR filter, characterizes its frequency selectivity, and develops a low-complexity subcarrier assignment and resource allocation scheme for enhanced performance.

Findings

Significantly increases minimum user rate compared to single-carrier baselines.

Robust performance under moderate line-of-sight blockage.

Efficient polynomial-time heuristic achieves near-optimal fairness.

Abstract

Pinching-antenna (PA) systems route millimeter wave (mmWave) signals through a leaky waveguide and radiate them at "pinch" apertures, offering low-cost line-of-sight (LoS) coverage. However, when multiple PAs serve multiple users simultaneously, the downlink channel becomes strongly frequency-selective, creating inter-symbol interference (ISI) that existing single-carrier designs overlook. This paper models the overall channel as a finite impulse response (FIR) filter, characterizes its frequency selectivity, and explicitly accounts for the resulting ISI. To overcome ISI, we introduce an orthogonal frequency-division multiple access (OFDMA)-based framework and formulate a max-min resource-allocation problem to achieve user fairness. A lightweight two-stage heuristic-greedy subcarrier assignment, followed by per-user water-filling, achieves near-optimal fairness with polynomial complexity. Simulation results for an indoor layout demonstrate that the proposed scheme notably increases the minimum user rate compared to time-division single-carrier baselines and remains robust under moderate LoS blockage.