Pinching-Antenna System Design under Random LoS and NLoS Channels

TL;DR

This paper develops optimization algorithms for pinching-antenna systems operating in realistic stochastic LoS and NLoS wireless channels, enhancing performance and reliability over traditional fixed-antenna setups.

Contribution

It introduces a probabilistic channel model for pinching antennas and proposes globally optimal, low-complexity algorithms for maximizing SNR metrics under realistic conditions.

Findings

Pinching antennas outperform fixed antennas in stochastic channels.

Proposed algorithms achieve globally optimal solutions efficiently.

Simulation results validate the effectiveness of the methods.

Abstract

Pinching antennas, realized through position-adjustable radiating elements along dielectric waveguides, have emerged as a promising flexible-antenna technology thanks to their ability to dynamically reshape large-scale channel conditions. However, most existing studies focus on idealized LoS-dominated environments, overlooking the stochastic nature of realistic wireless propagation. This paper investigates a more practical multiuser pinching-antenna system under a composite probabilistic channel model that captures distance-dependent LoS blockage and NLoS scattering. To account for both efficiency and reliability aspects of communication, two complementary design metrics are considered: an average signal-to-noise ratio (SNR) metric characterizing long-term throughput and fairness, and an outage-constrained metric ensuring a prescribed reliability level. Based on these metrics, we formulate two optimization problems: the first maximizes the max-min average SNR across users, while the second maximizes a guaranteed SNR threshold under per-user outage constraints. Although both problems are inherently nonconvex, we exploit their underlying monotonic structures and develop low-complexity, bisection-based algorithms that achieve globally optimal solutions using only simple scalar evaluations. Extensive simulations validate the effectiveness of the proposed methods and demonstrate that pinching-antenna systems significantly outperform conventional fixed-antenna designs even under random LoS and NLoS channels.