Performance Analysis of FAS-Assisted NOMA Communication Networks

Fluid antenna system (FAS) has attracted widespread attention as a cost-effective technological solution to enhance link reliability via dynamic antenna port selection. This paper investigates the integration of FAS into non-orthogonal multiple access (NOMA) networks where a couple of users equipped with fluid antenna are randomly distributed within a circle. To evaluate the performance of FAS-NOMA networks, we derive approximate outage probability and ergodic data rate expressions of non-orthogonal users. Based on these asymptotic results, the diversity orders of users are related with the number of ports and the length of FAS, while the high signal-to-noise ratio slopes are constant. In addition, the delay-constrained and latency-tolerant throughputs of FAS-NOMA networks are surveyed by selecting the optimal antenna port. Simulation results demonstrate that: 1) The outage behaviors of FAS-NOMA networks are superior to that of traditional antenna system (TAS) based NOMA and orthogonal multiple access (OMA) networks; 2) FAS-NOMA networks are capable of attaining the higher ergodic data rates than FAS-OMA and TAS-OMA networks; and 3) With the number of fluid antenna ports and FAS length increasing, the performance of FAS-NOMA networks is significantly enhanced.