A Minimum SER Design for a NOMA-Assisted Pinching-Antenna System

By adjusting antenna parameters, flexible antenna systems can dynamically reconfigure wireless channel characteristics to improve system performance. Non-orthogonal multiple access (NOMA) is a promising multiple access technique for enhancing the spectral efficiency and connectivity of next-generation wireless systems. A key research focus is how to leverage the synergy between NOMA and flexible antenna systems. A novel type of flexible antenna system called pinching-antenna system can provide line-of-sight (LoS) links to users by adjusting the position of the pinching antenna, mitigating large-scale fading. In this paper, we investigate how to implement reliable communication in a downlink NOMA-assisted pinching-antenna system by minimizing the symbol error rate (SER). We derive the SER expressions for NOMA-assisted pinching-antenna system users with QAM modulation, and minimize it with respect to the power allocation factor and the position of the pinching antenna. At higher-order modulation, it is revealed that the minimum SER strategy is for the pinching antenna to track the strong NOMA user. Finally, the analysis is verified by Monte Carlo simulation.