In Massive MIMO base stations (BSs), the hardware design needs to balance high spectral efficiency (SE) with low complexity. The level of hardware impairments (HWIs) indicates how strong the signal distortion introduced by hardware imperfections is. In particular, the analog-to-digital converters (ADCs) have an important impact on signal distortion and power consumption. This article addresses the fundamental problem of selecting the optimal hardware quality in the Massive MIMO space. In particular, we examine the optimal HWI and ADC bit allocation per BS antenna to maximize the SE. The results show that in co-located arrays with low channel gain variations across antennas, equal ADC bit allocation is optimal. In contrast, cell-free Massive MIMO systems benefit the most from optimizing the ADC bit allocation achieving improvements in the order of 2 [bit-per-channel-use] per user equipment when using regularized zero-forcing (RZF). In addition, when including the impact of power consumption in cell-free Massive MIMO with RZF, allocating low values of mixed ADC bit resolutions across the BS antennas can increase the energy efficiency up to 30% compared to equal ADC bit allocation.

中文翻译：

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相关和无蜂窝大规模 MIMO 中的最佳每天线 ADC 位分配

在大规模 MIMO 基站 (BS) 中，硬件设计需要在高频谱效率 (SE) 和低复杂度之间取得平衡。硬件损伤 (HWI) 的级别表示硬件缺陷引入的信号失真的严重程度。特别是，模数转换器 (ADC) 对信号失真和功耗具有重要影响。本文解决了在大规模 MIMO 空间中选择最佳硬件质量的基本问题。特别是，我们检查了每个 BS 天线的最佳 HWI 和 ADC 比特分配，以最大化 SE。结果表明，在具有低信道增益跨天线变化的协同定位阵列中，相等的 ADC 位分配是最佳的。相比之下，当使用正则化迫零 (RZF) 时，无细胞大规模 MIMO 系统从优化 ADC 比特分配中获益最多，每个用户设备实现了 2 [每信道使用比特] 数量级的改进。此外，当在具有 RZF 的无细胞大规模 MIMO 中包括功耗的影响时，在 BS 天线上分配混合 ADC 位分辨率的低值可以将能源效率提高多达 30%，与相等的 ADC 位分配相比。