This paper analyzes how the distortion created by hardware impairments in a multiple-antenna base station affects the uplink spectral efficiency (SE), with focus on Massive MIMO. This distortion is correlated across the antennas, but has been often approximated as uncorrelated to facilitate (tractable) SE analysis. To determine when this approximation is accurate, basic properties of distortion correlation are first uncovered. Then, we separately analyze the distortion correlation caused by third-order non-linearities and by quantization. Finally, we study the SE numerically and show that the distortion correlation can be safely neglected in Massive MIMO when there are sufficiently many users. Under i.i.d. Rayleigh fading and equal signal-to-noise ratios (SNRs), this occurs for more than five transmitting users. Other channel models and SNR variations have only minor impact on the accuracy. We also demonstrate the importance of taking the distortion characteristics into account in the receive combining.
翻译:本文分析了多层防波塔基站硬件缺陷造成的扭曲如何影响上链谱效率(SE), 重点是MIMO。 这种扭曲在天线上具有关联性, 但通常被近似为无关联性, 以便于SE分析( 可提取) 。 要确定这一近似值何时准确, 首先可以发现扭曲相关关系的基本特性 。 然后, 我们分别分析三阶非线性和量化造成的扭曲相关性 。 最后, 我们从数字角度研究 SE, 并表明当有足够多的用户使用MIMO时, 扭曲性相关关系可以安全地被忽视 。 根据 i. d. Rayleigh fading 和 等同的信号对音比( SNRs), 这对五个以上的传输用户来说, 。 其他频道模型和 SNR 变异只对准确性产生轻微影响 。 我们还证明在接收器组合中将扭曲性特性考虑在内的重要性 。