Performance Analysis of NOMA-Assisted Indoor Multi-Waveguide Pinching-Antenna Systems

Abstract

Pinching-antenna systems (PASS) have recently emerged as a promising flexible-antenna architecture for highfrequency indoor communications, due to their capability of creating reconfigurable radiation points along dielectric waveguides and establishing short-range strong links for users. In this paper, we propose an indoor downlink multi-waveguide PASS and study the position optimization of pinching antennas (PAs) along dielectric waveguides, where multiple users are distributed in a three-dimensional room and are associated with their nearest waveguides. To characterize practical indoor propagation, a blockage-aware Rician channel model is developed by jointly considering guided-wave propagation, free-space path loss, distance-dependent line-of-sight (LoS) probability, LoS penetration attenuation, and small-scale fading. On this basis, we propose a non-orthogonal multiple access (NOMA)-based multiuser transmission framework with inter-waveguide interference, successive interference cancellation (SIC) decoding, and qualityof-service (QoS)-aware rate constraints. Furthermore, PA position optimization is introduced to exploit the additional spatial degree of freedom provided by PASS. Results show that the proposed PASS-Movable scheme can effectively improve the sum rate, minimum user rate, and successful transmission probability, compared with fixed-position baseline schemes.