Learning to Fairly Classify the Quality of Wireless Links

TL;DR

This paper introduces a new tree-based machine learning model for wireless link quality classification that balances high performance, fairness for minority classes, and low training costs, addressing challenges in imbalanced datasets.

Contribution

The paper proposes a novel tree-based classifier that improves fairness and efficiency in wireless link quality estimation, outperforming other models on imbalanced datasets.

Findings

Non-linear models perform slightly better than linear models.

The proposed tree-based model offers the best trade-off between performance and fairness.

Single metric evaluations can hide unfair performance on minority classes.

Abstract

Machine learning (ML) has been used to develop increasingly accurate link quality estimators for wireless networks. However, more in-depth questions regarding the most suitable class of models, most suitable metrics and model performance on imbalanced datasets remain open. In this paper, we propose a new tree-based link quality classifier that meets high performance and fairly classifies the minority class and, at the same time, incurs low training cost. We compare the tree-based model, to a multilayer perceptron (MLP) non-linear model and two linear models, namely logistic regression (LR) and SVM, on a selected imbalanced dataset and evaluate their results using five different performance metrics. Our study shows that 1) non-linear models perform slightly better than linear models in general, 2) the proposed non-linear tree-based model yields the best performance trade-off considering F1, training time and fairness, 3) single metric aggregated evaluations based only on accuracy can hide poor, unfair performance especially on minority classes, and 4) it is possible to improve the performance on minority classes, by over 40% through feature selection and by over 20% through resampling, therefore leading to fairer classification results.