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，波达方向（DOA）测量因其可实现的高分辨率而迎来真正的复兴。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，进行性能分析，并评估其工程应用。可以预见，基于大规模接收MIMO的DOA估计仍面临诸多挑战，如高电路成本、高能耗及算法实现的高复杂度。针对这些问题，本文阐明新的研究与突破。随后，提出一种新型架构——采用低分辨率模数转换器（ADC）的混合模拟与数字（HAD）大规模接收MIMO，以在电路成本、复杂度与性能之间取得良好平衡。进一步，提出一种基于几何中心的新型三维（3D）到达角（AOA）定位方法，该方法可利用配备超大规模MIMO系统的单基站计算无源发射源的位置，并能达到克拉美罗下界（CRLB）。文中还分析了性能损失，以量化最小比特数。DOA估计将在诸多应用中发挥关键作用，例如定向调制、波束赋形跟踪与对准等6G技术。