Hybrid beamforming is a low-cost alternative to digital beamforming with its capability to operate with fewer radio frequency (RF) chains than antennas. However, the diminishing degree of freedom from utilizing fewer RF chains results in considerable performance degradation. To circumvent this setback, scheduling of energy harvesting (SEH) has been recently proposed to provide an additional degree of freedom. In this letter, we study the optimization of SEH together with the beamforming weights, energy and data transfer intervals, and uplink transmit power. The objective is minimizing the total duration of uplink and downlink transmission, whereas the constraints include minimum data transfer, maximum allowed transmit power and hybrid beamforming requirements. We formulate the non-convex optimization problem and convert it to the equivalent rank constrained semidefinite programming problem. We then propose efficient solution methodologies based on iteratively moving the rank constraints to the objective function as a penalty. Extensive simulations demonstrate that SEH is an effective circumvention to the RF chain scarcity, culminating in up to 26% delay performance gain.

中文翻译：

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MIMO无线供电通信网络中能量传输调度和功率控制的联合优化

混合波束赋形是数字波束赋形的低成本替代方案，与天线相比，它能够使用更少的射频 (RF) 链进行操作。然而，减少使用较少射频链的自由度会导致性能显着下降。为了避免这种挫折，最近提出了能量收集 (SEH) 调度以提供额外的自由度。在这封信中，我们研究了 SEH 的优化以及波束赋形权重、能量和数据传输间隔以及上行链路发射功率。目标是最小化上行链路和下行链路传输的总持续时间，而约束条件包括最小数据传输、最大允许发射功率和混合波束成形要求。我们制定了非凸优化问题并将其转换为等效秩约束半定规划问题。然后，我们提出了基于将秩约束迭代移动到目标函数作为惩罚的有效解决方法。大量模拟表明，SEH 是对 RF 链稀缺性的有效规避，最终将延迟性能提高了 26%。