# Evaluation of Low Complexity Massive MIMO Techniques Under Realistic Channel Conditions

## TL;DR

This paper evaluates a low complexity massive MIMO technique using a realistic channel model, proposing user scheduling and precoding methods based on channel correlation, balancing throughput and system complexity.

## Contribution

It introduces a novel user scheduling and precoding scheme leveraging the eigenvalue spectrum of the channel covariance matrix under realistic channel conditions.

## Key findings

- Throughput slightly decreases without CSIT
- System complexity is significantly reduced
- Effective user scheduling based on eigenvalue spectrum

## Abstract

A low complexity massive multiple-input multiple-output (MIMO) technique is studied with a geometry-based stochastic channel model, called COST 2100 model. We propose to exploit the discrete-time Fourier transform of the antenna correlation function to perform user scheduling. The proposed algorithm relies on a trade off between the number of occupied bins of the eigenvalue spectrum of the channel covariance matrix for each user and spectral overlap among the selected users. We next show that linear precoding design can be performed based only on the channel correlation matrix. The proposed scheme exploits the angular bins of the eigenvalue spectrum of the channel covariance matrix to build up an "approximate eigenchannels" for the users. We investigate the reduction of average system throughput with no channel state information at the transmitter (CSIT). Analysis and numerical results show that while the throughput slightly decreases due to the absence of CSIT, the complexity of the system is reduced significantly.