Massive multiple-input, multipleoutput (MIMO) is seen as an enabling technology for 5G communication systems [1]. Future base stations (BSs) featuring massive MIMO technology are expected to be equipped with a large number of antennas with digital beamforming structures, where the signals of all the channels are independently accessible. The array radiation pattern can be controlled via setting proper complex weights to the antenna elements to, e.g., form a beam in a desired direction to overcome the unfavorable propagation loss, or to form a null in an interference signal direction to suppress unwanted signals [2]. In addition, spatial multiplexing can also be utilized to serve multiple users simultaneously over the same time and frequency resource with various precoding schemes, which enlarges the network capacity.

中文翻译：

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短距离数字波束成形阵列的同步宽带校准 [测量角]

大规模多输入多输出 (MIMO) 被视为 5G 通信系统的使能技术 [1]。未来采用大规模 MIMO 技术的基站 (BS) 预计将配备大量具有数字波束成形结构的天线，所有信道的信号都可以独立访问。阵列辐射方向图可以通过为天线单元设置适当的复权重来控制，例如，在所需方向上形成波束以克服不利的传播损耗，或在干扰信号方向上形成零点以抑制不需要的信号 [2] ]。此外，还可以利用空间复用，通过多种预编码方案，在相同的时频资源上同时为多个用户服务，从而扩大网络容量。