Uplink Rate Maximization for Pinching Antenna-Assisted Covert Backscatter Communication

The emerging pinching antenna (PA) technology enables flexible antenna positioning for creating line-of-sight links, fundamentally reshaping the design of ambient signal-based backscatter communication (BSC). This correspondence investigates PA-assisted BSC (PA-BSC) for enhanced communication and covertness in the presence of a randomly distributed eavesdropper. The main challenge arises from the intrinsic coupling among energy harvesting, backscatter transmission, and covert constraints under spatial uncertainty. To address this, we formulate a non-convex optimization problem to maximize the uplink covert transmission rate by jointly optimizing the transmit power and antenna position, subject to both communication reliability and covertness constraints. An alternative optimization-based framework is developed to solve this coupled problem. Numerical results demonstrate that the proposed PA-BSC effectively mitigates the double near-far problem, where energy harvesting and backscatter transmission degrade simultaneously due to distance disparities, thereby improving both downlink energy harvesting and uplink data transmission while maintaining covertness performance under practical deployment scenarios.