Spectral and Energy Efficiency of Hybrid Precoding for mmWave Massive MIMO With Low-Resolution ADCs/DACs

In this paper, we investigate the spectral efficiency (SE) and energy efficiency (EE) of hybrid precoding in the point-to-point mmWave massive multiple-input multiple-output (MIMO) system with low-resolution analog-to-digital converters (ADCs) and digital-to-analog converters (DACs). First, considering the quantization noise of ADCs/DACs, an approximation expression for the SE is derived. Then, in order to solve the problem of non-convex hybrid precoding design, based on the derived analytical approximation expression, we propose a two-stage alternating minimization scheme to obtain the optimal hybrid precoder matrix. And the trade-offs between SE and EE with the full digital precoding and hybrid precoding are investigated. Numerical results verify that the system with the proposed scheme has nearly the same SE performance as with the full digital precoding. The fully connected hybrid precoding can be more energy-efficient compared to the full digital precoding, and the proposed hybrid precoding scheme can achieve the better trade-off between the SE and EE. Moreover, the increase in the resolution of ADCs/DACs can effectively improve the SE performance of the system, and 4-bits ADCs/DACs achieve the best EE performance for the hybrid precoding.