Performance Improvement for Multi-User Millimeter-Wave Massive MIMO Systems

Diego Fernando Carrera,Cesar Vargas-Rosales,Rafaela Villalpando-Hernandez,Jose Alejandro Galaviz-Aguilar

doi:10.1109/access.2020.2994176

Abstract

In this paper, we study the problem of optimizing the performance of multi-user millimeter-wave (mmWave) communications in three steps. The first one is given by the use of a new pilot mapping to reduce the inter-user interference effect and to perform more accurate channel estimation. In the second step, we designed a hybrid receiver that, based on the accuracy of the channel state information, chooses between the minimum mean square error (MMSE) and the multi-user regularized zero-forcing beamforming (RZFBF) receivers, to combine/precode the massive multiple-input multiple-output (MIMO) signal. In the third step, we propose to improve the beam direction with a slight change in the azimuth angle during the uplink communications to increase the multi-user efficiency and reduce inter-user interference. Numerical results show the performance increase using the proposed solutions in terms of the spectral efficiency by comparing the MMSE, RZFBF, and hybrid receivers.

Highlights

Millimeter-wave technology enables low latency communications and multi-gigabit data rates that widely leverage the potential of the fifth-generation (5G) New Radio (NR) standard
With the base station (BS) beam refinement, our objective is to analyze the performance of the hybrid receiver described in Section III-B with the spatial sparse precoding solution introduced in [36], which consists of maximizing the SINR in (4) with new analog and digital combiners, WnReFw and wnBeBw, respectively
By considering the pilot mapping of realistic NR systems, we developed a lowcomplexity pilot mapping solution that helps in the estimation of the channel state information (CSI) of mmWave channels, avoiding the interuser interference phenomenon

Summary

Introduction

Millimeter-wave (mmWave) technology enables low latency communications and multi-gigabit data rates that widely leverage the potential of the fifth-generation (5G) New Radio (NR) standard. The mmWave band allows packing massive multi-antenna arrays onto a small base station (BS) and dozens of antenna elements onto the user equipment (UE). This feature enables the use of genuinely massive multipleinput multiple-output (MIMO) technology for multi-user scenarios with very narrow beams that can achieve maximum directional gain [1], [2]. Digital beamforming is the state-of-the-art method that allows achieving the maximum spectral efficiency with massive MIMO systems. Hybrid beamforming techniques with variable phase shifters for analog RF processing are integrated to provide

Objectives

Results

Conclusion