Capacity analysis of OMA-PAS and NOMA-PAS

With the evolution of wireless communication technologies, pinching antenna system (PAS), as an emerging flexible antenna technology, offers a new perspective to address coverage and capacity issues in indoor wireless communications. Focusing on the multi-user downlink scenario, this paper establishes a system model based on Nakagami-m fading channels and conducts a comparative analysis of the performance of orthogonal multiple access (OMA) and non-orthogonal multiple access (NOMA) within PAS. By deriving exact analytical expressions for the ergodic sum rate and asymptotic closed-form results in the high signal-to-noise ratio (SNR) regime, the impact of key parameters, such as channel fading parameters and service area dimensions, on system performance is revealed. Theoretical and simulation results demonstrate that the NOMA protocol significantly enhances the spectral efficiency of PAS, exhibiting a distinct advantage particularly in the high SNR regime.