Directional Pinching-Antenna Systems

TL;DR

This paper introduces DiPASS, a realistic directional pinching-antenna system model that accurately captures antenna radiation, accounts for practical losses, and enables optimized deployment for future 6G networks.

Contribution

DiPASS is the first comprehensive channel model for pinching antennas that includes directional radiation, waveguide attenuation, and stochastic blockage, with new power allocation and optimization strategies.

Findings

Closed-form solutions for optimal antenna placement and orientation.

Waveguide diversity outperforms antenna density in capacity.

DiPASS provides a realistic benchmark for PASS-enabled 6G systems.

Abstract

We propose a directional pinching-antenna system (DiPASS), a comprehensive framework that transitions PASS modeling from idealized abstraction to physical consistency. DiPASS introduces the first channel model that accurately captures the directional, pencil-like radiation of pinching antennas, incorporates a practical waveguide attenuation of 1.3 dB/m, and accounts for stochastic line-of-sight blockage. A key enabler of DiPASS is our new "equal quota division" power allocation strategy, which guarantees predetermined coupling lengths independent of antenna positions, thereby overcoming a critical barrier to practical deployment. Our analysis yields foundational insights: we derive closed-form solutions for optimal antenna placement and orientation in single-PA scenarios, quantifying the core trade-off between waveguide and free-space losses. For multi-PA systems, we develop a scalable optimization framework that leverages directional sparsity, revealing that waveguide diversity surpasses antenna density in enhancing system capacity. Extensive simulations validate our analysis and demonstrate that DiPASS provides a realistic performance benchmark, fundamentally reshaping the understanding and design principles for future PASS-enabled 6G networks.