  Extremely large-scale array (XL-array) has emerged as a promising technology
to enhance the spectrum efficiency and spatial resolution in future wireless
networks, leading to a fundamental paradigm shift from conventional far-field
communications towards the new near-field communications. Different from the
existing works that mostly considered simultaneous wireless information and
power transfer (SWIPT) in the far field, we consider in this paper a new and
practical scenario, called mixed near- and far-field SWIPT, in which energy
harvesting (EH) and information decoding (ID) receivers are located in the
near- and far-field regions of the XL-array base station (BS), respectively.
Specifically, we formulate an optimization problem to maximize the weighted
sum-power harvested at all EH receivers by jointly designing the BS beam
scheduling and power allocation, under the constraints on the ID sum-rate and
BS transmit power. To solve this nonconvex optimization problem, an efficient
algorithm is proposed to obtain a suboptimal solution by leveraging the binary
variable elimination and successive convex approximation methods. Numerical
results demonstrate that our proposed joint design achieves substantial
performance gain over other benchmark schemes.
