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 maximum sum-rate and BS transmit power. To solve this nonconvex 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 without the optimization of beam scheduling and/or power allocation.

翻译：极大规模阵列（XL-array）已成为提升未来无线网络频谱效率和空间分辨率的重要技术，推动传统远场通信向新型近场通信的根本性范式转变。不同于现有工作主要考虑远场中的同步无线信息与能量传输（SWIPT），本文研究了一个新颖且实用的场景——混合近远场SWIPT，其中能量收集（EH）和信息解码（ID）接收机分别位于XL-array基站（BS）的近场和远场区域。具体而言，我们通过联合设计BS波束调度和功率分配，在满足最大和速率及BS发射功率约束的条件下，构建了最大化所有EH接收机加权和功率的优化问题。为解决这一非凸问题，我们提出了一种高效算法，通过引入二进制变量消除和逐次凸逼近方法获得次优解。数值结果表明，相较于未优化波束调度和/或功率分配的基线方案，本文提出的联合设计方法实现了显著的性能增益。