In this study, the authors propose a novel architecture based on the combination of peak-to-average power ratio (PAPR) reduction with digital beamforming (BF) for mm-wave massive multiple-input multiple-output (MIMO) systems. In order to keep the power amplifiers (PAs) working at the same input back-off thus maximising the system power efficiency, they propose to perform time-domain transmit beam-steering by adding progressive time delays to the signals at each antenna element, while keeping the amplitude weights unitary. They show that these time delays can be obtained with a finite impulse response filter implementation of time-domain fractional delay filter structures such as Lagrange interpolation polynomials. They also introduce an analysis on the PAPR of the interpolated signals, where they derive an upper bound to it and show that its value is similar to that of the signal at the input of the interpolation filters, showing the feasibility of the proposed method. In addition, they present a detailed analysis where they show that a significant reduction in computational complexity is obtained when compared to frequency-domain BF. Simulation results validate that the novel proposed scheme combining PAPR reduction and digital BF offers high-precision beam-steering maintaining reduced PAPR in the delayed signals fed to the antennas.

中文翻译：

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在大规模MIMO中提高能效：联合数字波束控制和音调保留PAPR降低

在这项研究中，作者针对毫米波大规模多输入多输出（MIMO）系统提出了一种基于峰均功率比（PAPR）降低与数字波束成形（BF）组合的新颖架构。为了使功率放大器（PA）在相同的输入回退状态下工作，从而最大程度地提高系统功率效率，他们建议通过在每个天线单元的信号上增加渐进的时间延迟来执行时域发射波束控制。保持振幅权重一致。他们表明，可以通过时域分数延迟滤波器结构（例如Lagrange插值多项式）的有限脉冲响应滤波器实现来获得这些时间延迟。他们还介绍了插值信号的PAPR分析，他们推导了它的上限，并表明其值与插值滤波器输入端的信号值相似，从而表明了该方法的可行性。此外，他们还进行了详细的分析，结果表明与频域BF相比，计算复杂度大大降低。仿真结果证明，结合了PAPR降低和数字BF的新提议方案可提供高精度的波束控制，从而在馈入天线的延迟信号中保持降低的PAPR。