Integrating large-scale antenna arrays is essential for overcoming capacity limitations in wireless communications. In this work, we examine a novel sixth-generation (6G) secure simultaneous wireless information and power transfer (SWIPT) system, where a transmitter equipped with an extremely large-scale antenna array (ELAA) operates in the near-field region. In our design, the transmitter concurrently delivers confidential data to information receivers and energy to zero-energy devices (ZEDs) via non-orthogonal multiple access (NOMA). A key innovation of our approach is the specialized near-field beamfocusing technique derived from a three-dimensional spherical channel model, which explicitly accounts for the unique propagation characteristics of near-field communications and distinguishes our method from traditional far-field designs. We formulate a non-convex optimization problem aimed at maximizing the secrecy rate while satisfying minimum quality-of-service and energy harvesting requirements. To solve this problem, we develop an iterative algorithm based on weighted sum-rate maximization and sequential convex approximations that effectively mitigate interference and enhance beamfocusing performance. Numerical simulations demonstrate that, with a 64-element uniform linear array and 40 dBm transmit power, our near-field NOMA system achieves an 18.41% higher secrecy rate than near-field spatial division multiple access (SDMA) and a 36.78-fold improvement over near-field orthogonal multiple access (OMA), along with a 6.39 dBm increase in harvested power relative to SDMA. These results underscore the critical role of specialized near-field design in next-generation 6G networks and its significant implications for industrial internet-of-things (IoT) and Industry 4.0 applications.

Pinching-antenna systems (PASS) route energy through low-loss dielectric waveguides and radiate via reconfigurable pinching antennas (PAs), enabling large, shapeable apertures with minimal radio chains. We study a near-field multicast downlink network that extends single-waveguide PASS to a coordinated multi-waveguide array and jointly optimizes PA positions and beams. We first develop a cascaded channel that couples in-waveguide and free-space propagation, and pose a worst-case multicast objective under spacing, coupling span, and power constraints. A two-stage co-design then follows. Stage I performs layout planning as a constrained bi-objective placement that maximizes the worst-user signal-to-noise ratio (SNR) while minimizing a wrapped-phase residual; when solved with the non-dominated sorting genetic algorithm (NSGA) II, it yields feasible Pareto layouts. Stage II fixes a knee layout obtained from Stage I and refines the multicast beam via a convex semi-definite relaxation (SDR)-successive convex approximation (SCA) formulation with a feasibility warm start, thereby recovering rank-one beams. Numerical results reveal that over wide ranges of transmit power, coupling span, PA per waveguide, number of waveguides, user count, user range, and base-station height, the proposed design outperforms a single-waveguide PASS and$\boldsymbol {x}$or$\boldsymbol {y}$-aligned uniform linear arrays, delivering higher worst-user rates as well as sharply lowering the per-user rate variance. The study also identifies broad coupling-length ranges where gains saturate and shows that a moderate number of pinches and additional waveguides help improve spatial coverage until a geometry-limited plateau is reached. These effects arise from in-waveguide proximity and lateral phase control, positioning multi-waveguide PASS as a practical, flexible antenna option for next-generation communication.

Intelligent metasurfaces are emerging as a key technology for future wireless systems, enabling programmable control of electromagnetic wave propagation. Compared to conventional single-layer reconfigurable intelligent surfaces (RIS), stacked intelligent metasurfaces (SIM) introduce multiple reconfigurable layers to provide more flexible and precise beamforming. This paper investigates the integration of SIM into a downlink non-orthogonal multiple access (NOMA) system to improve spectral efficiency while maintaining low hardware complexity. The proposed system combines maximum ratio transmission (MRT) precoding at the base station, SIM-assisted analog beamforming, and NOMA-based power allocation. To maximize the system sum rate, we perform joint optimization of SIM phase shifts and user power levels through an alternating optimization (AO) framework, where each variable is updated iteratively while the other is held fixed. We evaluate three SIM-assisted strategies: NOMA, water-filling, and uniform power allocation. Simulation results demonstrate that the SIM-NOMA configuration achieves the 40% sum rate improvements, outperforming the other schemes while leveraging the low-cost wave-domain processing capabilities of SIM.

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.