Hybrid beamforming design for near-field SWIPT networks

A near-field simultaneous wireless information and power transfer (SWIPT) network is investigated, where the hybrid beamforming architecture is employed at the base station to send the information beams for information transmission while charging energy harvesting users. A transmit power minimization problem is formulated by jointly optimizing the analog beamformer and the baseband digital beamformers. To tackle the non-convex optimization problem, a penalty-based two-layer (PTL) algorithm is proposed to optimize the analog beamformer and baseband digital information beamformers. By employing the block coordinate descent method, the optimal analog beamformer, and baseband digital information beamformers are obtained in the closed-form expressions. Moreover, a low-complexity two-stage algorithm to reduce the high computational complexity caused by the large number of antennas is proposed. Numerical results illustrate that: 1) the proposed PTL algorithm can achieve near-optimal performance; and 2) in contrast to the far-field SWIPT, a single near-field beamformer can focus the energy on multiple locations.