Uplink Spectral Efficiency of Massive MIMO with Spatially Correlated Rician Fading

TL;DR

This paper analyzes the uplink spectral efficiency of Massive MIMO systems under spatially correlated Rician fading, deriving closed-form expressions and comparing estimators to show the benefits of LoS paths.

Contribution

It introduces a comprehensive analysis of uplink spectral efficiency in Massive MIMO with Rician fading, including new statistical properties and closed-form SE expressions.

Findings

MMSE estimator outperforms LS estimator, especially with more antennas.

Rician fading yields higher spectral efficiency than Rayleigh fading.

LoS paths significantly enhance the sum spectral efficiency.

Abstract

This paper considers the uplink (UL) of a multi-cell Massive MIMO (multiple-input multiple-output) system with spatially correlated Rician fading channels. The channel model is composed of a deterministic line-of-sight (LoS) path and a stochastic non-line-of-sight (NLoS) component describing a spatially correlated multipath environment. We derive the statistical properties of the minimum mean squared error (MMSE) and least-square (LS) channel estimates for this model. Using these estimates for maximum ratio (MR) combining, rigorous closed-form UL spectral efficiency (SE) expressions are derived. Numerical results show that the SE is higher when using the MMSE estimator than the LS estimator, and the performance gap increases with the number of antennas. Moreover, Rician fading provides higher achievable SEs than Rayleigh fading since the LoS path improves the sum SE.