As massive multiple-input multiple-output (MIMO) becomes popular, direction of arrival (DOA) measurement has been made a real renaissance due to the high-resolution achieved. Thus, there is no doubt about DOA estimation using massive MIMO. The purpose of this paper is to describe its basic principles and key techniques, to present the performance analysis, and to appreciate its engineering applications. It is anticipated that there are still many challenges in DOA estimation using massive receive MIMO, such as high circuit cost, high energy consumption and high complexity of the algorithm implementation. New researches and breakthroughs are illustrated to deal with those problems. Then, a new architecture, hybrid analog and digital (HAD) massive receive MIMO with low-resolution ADCs, is presented to strike a good balance among circuit cost, complexity and performance. Then, a novel three-dimensional (3D) angle of arrival (AOA) localization method based on geometrical center is proposed to compute the position of a passive emitter using single base station equipped with an ultra-massive MIMO system. And, it can achieve the Cramer-Rao low bound (CRLB). Here, the performance loss is also analyzed to quantify the minimum number of bits. DOA estimation will play a key role in lots of applications, such as directional modulation, beamforming tracking and alignment for 6G.

翻译：随着大规模多输入多输出（MIMO）技术的普及，方向到达角（DOA）测量因其高分辨率特性而迎来真正的复兴。因此，利用大规模MIMO进行DOA估计已毋庸置疑。本文旨在阐述其基本原理与关键技术，呈现性能分析，并评估其工程应用价值。可以预见，利用大规模接收MIMO进行DOA估计仍面临诸多挑战，例如高电路成本、高能耗以及算法实现的高复杂度。为应对这些问题，本文介绍了相关新研究与突破。随后，提出了一种新型混合模数（HAD）大规模接收MIMO架构，该架构采用低分辨率模数转换器（ADC），可在电路成本、复杂度与性能之间实现良好平衡。接着，提出了一种基于几何中心的新型三维（3D）到达角（AOA）定位方法，该方法利用配备超大规模MIMO系统的单基站计算无源发射源的位置，并可达到克拉美罗下界（CRLB）。同时，分析了性能损失，以量化所需的最小比特数。DOA估计将在诸多应用中发挥关键作用，例如方向调制、波束赋形跟踪与对准，以及6G技术。