Digital phased arrays have often been disregarded for millimeter-wave communications since the analog-to-digital converters (ADCs) are power-hungry. In this paper, we provide a different perspective on this matter by demonstrating analytically and numerically how the ADC resolution can be reduced when using digital phased arrays. We perform a theoretical analysis of the quantization noise characteristics for an OFDM signal received and processed by a digital phased array, using Gaussian approximation of the OFDM signal. In particular, we quantify the quantization noise suppression factor analytically and numerically. This factor describes how much the coherent combining reduces the quantization noise as a function of the number of antennas, which allows for reducing the ADC bit resolution. For instance in a 8-16 antenna digital phased array the ADC resolution can be reduced with 1-2 bits compared to the ADC required for an analog phased array.

翻译：数字相控阵由于模数转换器（ADC）功耗较高，在毫米波通信中常被忽视。本文通过解析与数值分析，展示了在使用数字相控阵时如何降低ADC分辨率，为此问题提供了新的视角。我们利用OFDM信号的高斯近似，对数字相控阵接收并处理OFDM信号时的量化噪声特性进行了理论分析，特别地，通过解析与数值方法量化了量化噪声抑制因子。该因子描述了相干合并随天线数目变化对量化噪声的抑制程度，从而实现ADC比特分辨率的降低。例如，在8-16天线数字相控阵中，相较于模拟相控阵所需的ADC，其分辨率可降低1-2比特。