A Weighted Loss Approach to Robust Federated Learning under Data Heterogeneity

Fuente: arXiv
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Auteurs principaux: Erbani, Johan, Mokhtar, Sonia Ben, Portier, Pierre-Edouard, Egyed-Zsigmond, Elod, Nurbakova, Diana
Format: Preprint
Publié: 2025
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author Erbani, Johan
Mokhtar, Sonia Ben
Portier, Pierre-Edouard
Egyed-Zsigmond, Elod
Nurbakova, Diana
author_facet Erbani, Johan
Mokhtar, Sonia Ben
Portier, Pierre-Edouard
Egyed-Zsigmond, Elod
Nurbakova, Diana
contents Federated learning (FL) is a machine learning paradigm that enables multiple data holders to collaboratively train a machine learning model without sharing their training data with external parties. In this paradigm, workers locally update a model and share with a central server their updated gradients (or model parameters). While FL seems appealing from a privacy perspective, it opens a number of threats from a security perspective as (Byzantine) participants can contribute poisonous gradients (or model parameters) harming model convergence. Byzantine-resilient FL addresses this issue by ensuring that the training proceeds as if Byzantine participants were absent. Towards this purpose, common strategies ignore outlier gradients during model aggregation, assuming that Byzantine gradients deviate more from honest gradients than honest gradients do from each other. However, in heterogeneous settings, honest gradients may differ significantly, making it difficult to distinguish honest outliers from Byzantine ones. In this paper, we introduce the Worker Label Alignement Loss (WoLA), a weighted loss that aligns honest worker gradients despite data heterogeneity, which facilitates the identification of Byzantines' gradients. This approach significantly outperforms state-of-the-art methods in heterogeneous settings. In this paper, we provide both theoretical insights and empirical evidence of its effectiveness.
format Preprint
id arxiv_https___arxiv_org_abs_2506_09824
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Weighted Loss Approach to Robust Federated Learning under Data Heterogeneity
Erbani, Johan
Mokhtar, Sonia Ben
Portier, Pierre-Edouard
Egyed-Zsigmond, Elod
Nurbakova, Diana
Machine Learning
Federated learning (FL) is a machine learning paradigm that enables multiple data holders to collaboratively train a machine learning model without sharing their training data with external parties. In this paradigm, workers locally update a model and share with a central server their updated gradients (or model parameters). While FL seems appealing from a privacy perspective, it opens a number of threats from a security perspective as (Byzantine) participants can contribute poisonous gradients (or model parameters) harming model convergence. Byzantine-resilient FL addresses this issue by ensuring that the training proceeds as if Byzantine participants were absent. Towards this purpose, common strategies ignore outlier gradients during model aggregation, assuming that Byzantine gradients deviate more from honest gradients than honest gradients do from each other. However, in heterogeneous settings, honest gradients may differ significantly, making it difficult to distinguish honest outliers from Byzantine ones. In this paper, we introduce the Worker Label Alignement Loss (WoLA), a weighted loss that aligns honest worker gradients despite data heterogeneity, which facilitates the identification of Byzantines' gradients. This approach significantly outperforms state-of-the-art methods in heterogeneous settings. In this paper, we provide both theoretical insights and empirical evidence of its effectiveness.
title A Weighted Loss Approach to Robust Federated Learning under Data Heterogeneity
topic Machine Learning
url https://arxiv.org/abs/2506.09824