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arXiv 2310.20186eess.SP
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混合近场与远场信道中的SWIPT:联合波束调度与功率分配

SWIPT in Mixed Near- and Far-Field Channels: Joint Beam Scheduling and Power Allocation

Yunpu Zhang, Changsheng You

AI总结:

本文研究超大规模阵列基站下混合近场与远场的SWIPT场景,通过联合优化波束调度和功率分配最大化能量收集总功率,并提出高效求解算法,显著优于未联合优化的基准方案。

摘要:

超大规模阵列(XL-array)已成为一项有前景的技术,通过利用大量天线生成笔形波束成形,提升未来无线网络的频谱效率和空间分辨率。这也带来了从传统远场通信向新型近场通信的根本范式转变。与现有大多考虑远场同时无线信息和功率传输(SWIPT)的工作不同,本文考虑一种新的实用场景,称为混合近场与远场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,我们构建了一个优化问题,在最大总速率和基站发射功率的约束下,通过联合设计基站波束调度和功率分配,最大化所有EH接收机收集的加权总功率。首先,针对具有多个EH和ID接收机的一般情况,我们提出一种高效算法,利用二进制变量消除和逐次凸近似方法获得次优解。为获得有用见解,我们随后研究了特殊情况的联合设计。特别地,我们证明当存在多个EH接收机和一个ID接收机时,在大多数情况下,最优设计是将一部分功率分配给ID接收机以满足速率约束,而将剩余功率分配给具有最高EH能力的一个EH接收机。这与传统远场SWIPT情况形成鲜明对比,后者应将所有功率分配给ID接收机。数值结果表明,我们提出的联合设计显著优于未优化波束调度和/或功率分配的其他基准方案。

英文摘要:

Extremely large-scale array (XL-array) has emerged as a promising technology to enhance the spectrum efficiency and spatial resolution in future wireless networks by exploiting massive number of antennas for generating pencil-like beamforming. This also leads to a fundamental paradigm shift from conventional far-field communications towards the new near-field communications. In contrast to 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, where 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. First, for the general case with multiple EH and ID receivers, we propose an efficient algorithm to obtain a suboptimal solution by utilizing the binary variable elimination and successive convex approximation methods. To obtain useful insights, we then study the joint design for special cases. In particular, we show that when there are multiple EH receivers and one ID receiver, in most cases, the optimal design is allocating a portion of power to the ID receiver for satisfying the rate constraint, while the remaining power is allocated to one EH receiver with the highest EH capability. This is in sharp contrast to the conventional far-field SWIPT case, for which all powers should be allocated to ID receivers. Numerical results show that our proposed joint design significantly outperforms other benchmark schemes without the optimization of beam scheduling and/or power allocation.

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