Fairness-Oriented Transmission Design in PASS-Assisted Backscatter Communication Networks

In this work, we investigate a pinching antenna system (PASS)-assisted backscatter communication network, where multiple backscatter devices (BDs) utilize signals from a dielectric waveguide for both energy harvesting and backscattering communication. To guarantee communication fairness among all BDs, we formulate a max-min rate optimization problem by jointly optimizing the positions of the pinching antennas (PAs) and the time allocation of the BDs. Then, by employing an alternating optimization (AO) algorithm, the original problem is decomposed into three tractable subproblems and solved iteratively. To mitigate the combined impact of large-scale path loss and small-scale phase variation in the optimization of PA positions, a two-stage optimization strategy is proposed to decouple these effects and solve them sequentially. Finally, simulation results illustrate that the proposed scheme outperforms the benchmark schemes such as the conventional multiple-input multiple-output scheme and the fixed-position scheme, and achieves nearly the same performance as an ideal scheme where small-scale phase effect is perfectly eliminated.