Power Minimization for Multi-Waveguide-Driven NOMA-Assisted Uplink Pinching Antenna Systems

The pinching antenna system has recently garnered significant attention due to its capability to enable line-of-sight (LoS) connections and efficiently reduce large-scale path loss. Owing to its inherent architecture, the pinching antenna is particularly well-suited for integration with non-orthogonal multiple access (NOMA) to facilitate multi-user signal transmission. This work is the first to investigate the power minimization problem for NOMA-assisted uplink pinching antenna systems with multiple waveguides by jointly optimizing the users' decoding order and their transmission power allocation, while considering each user's minimum data rate requirement. To address this challenging optimization problem, we first determine the optimal decoding order for users associated with the same waveguide in terms of power minimization. Subsequently, we efficiently solve the original problem using a distributed iterative algorithm. We rigorously demonstrate that the proposed joint optimization approach converges to a unique fixed point, provided that the problem is feasible. Extensive simulation results validate the efficiency and effectiveness of our proposed solution.