Enhancement of Spectral and Energy efficiencies of MU-Massive MIMO Systems Employing one-bit A/Ds at Millimeter Waves

Abstract

The energy efficiency (EE) is defined as the ratio of spectral efficiency (SE) to power consumption (PC). Therefore, to enhance the EE of the millimeter wave (mm-Wave) massive multiple-input multiple-output (MIMO) systems, the SE must be enhanced or the resolution bits of analogue to digital converters (A/Ds) and digital to analogue converters (D/As) must be reduced. However, reducing the resolution bits leads to SE degradation, it also reduces the PC and increases the quantization noise. To tackle this challenge, we introduce a hybrid precoding and beamforming structure (HP-BF) while using one-bit A/Ds at transceivers for multi-user (MU) massive MIMO systems. The proposed HP-BF mitigates the issues arising from using one-bit resolution via applying digital antenna array beamforming at the base station. The proposed HP-BF is based on the synthesis of the linear antenna array using the well-known GA/L1 beamforming technique for maximum gain realization using the existing transmit antenna elements. This gain maximization enhances the received signal to noise ratio (SNR) giving rise to enhanced SE without adding any complexity to the system. In addition, the PC issue of A/Ds is eliminated due to using one-bit resolution. Thereby, the EE of the proposed HP-BF is enhanced due to SE enhancement and PC minimization. The simulation results exhibit a significant improvement in SE and EE of the proposed system.