Near-Field Secure Communications with NOMA-Assisted SWIPT Systems

This article investigates a near-field secure simultaneous wireless information and power transfer (SWIPT) network employing a non-orthogonal multiple access (NOMA) scheme. In this network, a base station equipped with an extremely largescale array antenna (ELAA) communicates with and transfers power to multiple single-antenna zero-energy devices (ZEDs) within the near-field region, while an eavesdropper attempts to wiretap the communication by intercepting the information signals. Specifically, we aim to maximize the overall secrecy sum rate of the ZEDs while ensuring a minimum energy harvesting criterion at the ZEDs. Consequently, a non-convex resource optimization problem is formulated and solved using an iterative approach, leveraging weighted sum-rate maximization via minorization-maximization (WSR-MM) with second-order cone programming (SOCP) transformation and general convex approximations. Finally, numerical results are presented to demonstrate the performance of the proposed near-field secure SWIPT system under varying network parameters.