Exploiting the Preferred Domain of FDD Massive MIMO Systems with Uniform Planar Arrays

TL;DR

This paper proposes using an extra one-bit feedback in FDD massive MIMO systems with UPA antennas to improve channel state information accuracy by exploiting the preferred domain, enhancing system performance.

Contribution

It introduces a novel feedback scheme that indicates the preferred domain, combined with variable-rate CSI quantization, to significantly improve CSI quality in UPA-based massive MIMO systems.

Findings

Additional one-bit feedback improves CSI accuracy.

Variable-rate CSI quantization enhances system performance.

Numerical results confirm significant quality gains.

Abstract

Massive multiple-input multiple-output (MIMO) systems hold the potential to be an enabling technology for 5G cellular. Uniform planar array (UPA) antenna structures are a focus of much commercial discussion because of their ability to enable a large number of antennas in a relatively small area. With UPA antenna structures, the base station can control the beam direction in both the horizontal and vertical domains simultaneously. However, channel conditions may dictate that one dimension requires higher channel state information (CSI) accuracy than the other. We propose the use of an additional one bit of feedback information sent from the user to the base station to indicate the preferred domain on top of the feedback overhead of CSI quantization in frequency division duplexing (FDD) massive MIMO systems. Combined with variable-rate CSI quantization schemes, the numerical studies show that the additional one bit of feedback can increase the quality of CSI significantly for UPA antenna structures.