Performance of multi-user massive mimo in 5G NR networks at 28 GHz band

With the increasing demand of millimeter-wave (mmWave) frequencies in 5G wireless communication technologies, investigations on techniques to improve spectral efficiency became an important aspect. There are mainly two techniques present in 5G wireless systems, named "hybrid beamforming,"that are used to reduce the system cost and "massive multi-input-multi-output (mMIMO)"to improve spectral efficiencies. In this paper, a single-cell downlink multi-user-mMIMO (MU-mMIMO) hybrid beamforming communication system is considered with multiple data streams per user that uses a generic channel model with accurate channel state information (CSI) and emphasizes partitioning of precoding into digital baseband domain and RF analog domain at transmitter (Tx) end, also combining the digital baseband domain and RF analog domain at the receiver (Rx) end. We believe that MU-mMIMO operation will be much more popular for 5G NR, considering the wide deployment of mMIMO in some major NR frequency bands. This paper gives a performance analysis of a MU-mMIMO hybrid beamforming communication system at 28 GHz frequency band with multiple number of base station (BS) antennas and quadrature amplitude modulation (QAM) schemes, and compares their performance. It also gives the tradeoff between beamforming gains to overcome path loss and reduce hardware cost and power consumption. Simulation results include receive constellation of the equalized symbols that give qualitative analysis and RMS EVM values for quantitative analysis.