Learning Optimal Linear Precoding for Cell-Free Massive MIMO with GNN

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Hauptverfasser: Parlier, Benjamin, Salaün, Lou, Yang, Hong
Format: Preprint
Veröffentlicht: 2024
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author Parlier, Benjamin
Salaün, Lou
Yang, Hong
author_facet Parlier, Benjamin
Salaün, Lou
Yang, Hong
contents We develop a graph neural network (GNN) to compute, within a time budget of 1 to 2 milliseconds required by practical systems, the optimal linear precoder (OLP) maximizing the minimal downlink user data rate for a Cell-Free Massive MIMO system - a key 6G wireless technology. The state-of-the-art method is a bisection search on second order cone programming feasibility test (B-SOCP) which is a magnitude too slow for practical systems. Our approach relies on representing OLP as a node-level prediction task on a graph. We construct a graph that accurately captures the interdependence relation between access points (APs) and user equipments (UEs), and the permutation equivariance of the Max-Min problem. Our neural network, named OLP-GNN, is trained on data obtained by B-SOCP. We tailor the OLP-GNN size, together with several artful data preprocessing and postprocessing methods to meet the runtime requirement. We show by extensive simulations that it achieves near optimal spectral efficiency in a range of scenarios with different number of APs and UEs, and for both line-of-sight and non-line-of-sight radio propagation environments.
format Preprint
id arxiv_https___arxiv_org_abs_2406_04456
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Learning Optimal Linear Precoding for Cell-Free Massive MIMO with GNN
Parlier, Benjamin
Salaün, Lou
Yang, Hong
Signal Processing
Artificial Intelligence
Machine Learning
We develop a graph neural network (GNN) to compute, within a time budget of 1 to 2 milliseconds required by practical systems, the optimal linear precoder (OLP) maximizing the minimal downlink user data rate for a Cell-Free Massive MIMO system - a key 6G wireless technology. The state-of-the-art method is a bisection search on second order cone programming feasibility test (B-SOCP) which is a magnitude too slow for practical systems. Our approach relies on representing OLP as a node-level prediction task on a graph. We construct a graph that accurately captures the interdependence relation between access points (APs) and user equipments (UEs), and the permutation equivariance of the Max-Min problem. Our neural network, named OLP-GNN, is trained on data obtained by B-SOCP. We tailor the OLP-GNN size, together with several artful data preprocessing and postprocessing methods to meet the runtime requirement. We show by extensive simulations that it achieves near optimal spectral efficiency in a range of scenarios with different number of APs and UEs, and for both line-of-sight and non-line-of-sight radio propagation environments.
title Learning Optimal Linear Precoding for Cell-Free Massive MIMO with GNN
topic Signal Processing
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2406.04456