Fading Margins for Large-Scale Antenna Systems

TL;DR

This paper evaluates the fading margins in large-scale antenna systems for 5G, showing that increasing antenna elements beyond 32 offers minimal additional diversity benefits in real-world scenarios.

Contribution

It provides an empirical analysis of fading margins in massive MIMO systems and compares them to theoretical models, highlighting practical deployment trade-offs.

Findings

Little additional diversity is gained with more than 32 antennas.

Empirical fading margins are close to theoretical maximum diversity.

Trade-off between deployment size and channel hardening benefits.

Abstract

Mobile phone operators have begun the roll-out of 5G networks, deploying massive MIMO base stations. Commercial product ranges start with 16 independent radio chains connected to a large-scale antenna system to exploit both channel hardening and favourable propagation in order to obtain increased spectral efficiency. In this work, the cumulative distribution function describing the gain for large-scale antenna systems considering spatial and spectral diversity is evaluated empirically in terms of a fading margin and compared to an analytical maximum diversity reference system. This allows for a simple investigation of the trade-off between deployment size and exploitation of channel hardening. For the considered site-specific measurement data, little additional diversity is harvested with systems larger than 32 antenna elements.