Asymptotic analysis of downlink MIMO systems over Rician fading channels

TL;DR

This paper derives an asymptotic expression for the ergodic sum rate of large-scale multi-user MIMO systems with Rician fading, using random matrix theory to analyze the impact of system parameters and channel conditions.

Contribution

It provides a novel asymptotic analysis of downlink MIMO systems over Rician channels with correlated fading, extending large system analysis techniques.

Findings

Asymptotic sum rate expression derived for large N and K

Performance gap analyzed between asymptotic and finite systems

Impact of Rician factor and spatial correlation quantified

Abstract

In this work, we focus on the ergodic sum rate in the downlink of a single-cell large-scale multi-user MIMO system in which the base station employs N antennas to communicate with $K$ single-antenna user equipments. A regularized zero-forcing (RZF) scheme is used for precoding under the assumption that each link forms a spatially correlated MIMO Rician fading channel. The analysis is conducted assuming $N$ and $K$ grow large with a non trivial ratio and perfect channel state information is available at the base station. Recent results from random matrix theory and large system analysis are used to compute an asymptotic expression of the signal-to-interference- plus-noise ratio as a function of the system parameters, the spatial correlation matrix and the Rician factor. Numerical results are used to evaluate the performance gap in the finite system regime under different operating conditions.