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Main Authors: Lee, Gyuejeong, Shin, Jihwan, Choi, Daeyoung
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2507.04310
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author Lee, Gyuejeong
Shin, Jihwan
Choi, Daeyoung
author_facet Lee, Gyuejeong
Shin, Jihwan
Choi, Daeyoung
contents Heterogeneity in data distributions and model architectures remains a significant challenge in federated learning (FL). Various heterogeneous FL (HtFL) approaches have recently been proposed to address this challenge. Among them, prototype-based FL (PBFL) has emerged as a practical framework that only shares per-class mean activations from the penultimate layer. However, PBFL approaches often suffer from suboptimal prototype separation, limiting their discriminative power. We propose Prototype Normalization (ProtoNorm), a novel PBFL framework that addresses this limitation through two key components: Prototype Alignment (PA) and Prototype Upscaling (PU). The PA method draws inspiration from the Thomson problem in classical physics, optimizing global prototype configurations on a unit sphere to maximize angular separation; subsequently, the PU method increases prototype magnitudes to enhance separation in Euclidean space. Extensive evaluations on benchmark datasets show that our approach better separates prototypes and thus consistently outperforms existing HtFL approaches. Notably, since ProtoNorm inherits the communication efficiency of PBFL and the PA is performed server-side, it is particularly suitable for resource-constrained environments.
format Preprint
id arxiv_https___arxiv_org_abs_2507_04310
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Heterogeneous Federated Learning with Prototype Alignment and Upscaling
Lee, Gyuejeong
Shin, Jihwan
Choi, Daeyoung
Machine Learning
Distributed, Parallel, and Cluster Computing
Heterogeneity in data distributions and model architectures remains a significant challenge in federated learning (FL). Various heterogeneous FL (HtFL) approaches have recently been proposed to address this challenge. Among them, prototype-based FL (PBFL) has emerged as a practical framework that only shares per-class mean activations from the penultimate layer. However, PBFL approaches often suffer from suboptimal prototype separation, limiting their discriminative power. We propose Prototype Normalization (ProtoNorm), a novel PBFL framework that addresses this limitation through two key components: Prototype Alignment (PA) and Prototype Upscaling (PU). The PA method draws inspiration from the Thomson problem in classical physics, optimizing global prototype configurations on a unit sphere to maximize angular separation; subsequently, the PU method increases prototype magnitudes to enhance separation in Euclidean space. Extensive evaluations on benchmark datasets show that our approach better separates prototypes and thus consistently outperforms existing HtFL approaches. Notably, since ProtoNorm inherits the communication efficiency of PBFL and the PA is performed server-side, it is particularly suitable for resource-constrained environments.
title Heterogeneous Federated Learning with Prototype Alignment and Upscaling
topic Machine Learning
Distributed, Parallel, and Cluster Computing
url https://arxiv.org/abs/2507.04310