Millimeter Wave Massive MIMO Downlink Per-Group Communications with Hybrid Linear Precoding

TL;DR

This paper proposes a hybrid linear precoding scheme for millimeter-wave massive MIMO downlink, effectively grouping users and employing advanced precoding techniques to enhance throughput and interference management.

Contribution

It introduces a novel group classification and precoding approach using three subcarrier frequencies and VCMB, improving throughput and interference handling in millimeter-wave massive MIMO systems.

Findings

High throughput groups achieved with three subcarrier frequencies

Significant performance improvement of ZF-PGP over ZFP

Effective user grouping and precoding strategies demonstrated

Abstract

We address the problem of analyzing and classifying in groups the downlink channel environment in a millimeter-wavelength cell, accounting for path loss, multipath fading, and User Equipment (UE) blocking, by employing a hybrid propagation and multipath fading model, thus using accurate inter-group interference modeling. The base station (BS) employs a large Uniform Planar Array (UPA) to facilitate massive Multiple-Input, Multiple-Output (MIMO) communications with high efficiency. UEs are equipped with a single antenna and are distributed uniformly within the cell. The key problem is analyzing and defining groups toward precoding. Because equitable type of throughput is desired between groups, Combined Frequency and Spatial Division and Multiplexing (CFSDM) prevails as necessary. We show that by employing three subcarrier frequencies, the UEs can be efficiently separated into high throughput groups, with each group employing Virtual Channel Model Beams (VCMB) based inner precoding, followed by efficient Multi-User Multiple-Input Multiple-Output (MU-MIMO) outer precoders. For each group, we study three different sub-grouping methods offering different advantages. We show that the improvement offered by Zero-Forcing Per-Group Precoding (ZF-PGP) over Zero-Forcing Precoding (ZFP) is very high.