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arXiv · 2501.17512

A survey on Clustered Federated Learning: Taxonomy, Analysis and Applications

Michael Ben Ali·Omar El-Rifai·Imen Megdiche·André Peninou·Olivier Teste
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Abstract

As Federated Learning (FL) expands, the challenge of non-independent and identically distributed (non-IID) data becomes critical. Clustered Federated Learning (CFL) addresses this by training multiple specialized models, each representing a group of clients with similar data distributions. However, the term ''CFL'' has increasingly been applied to operational strategies unrelated to data heterogeneity, creating significant ambiguity. This survey provides a systematic review of the CFL literature and introduces a principled taxonomy that classifies algorithms into Server-side, Client-side, and Metadata-based approaches. Our analysis reveals a distinct dichotomy: while theoretical research prioritizes privacy-preserving Server/Client-side methods, real-world applications in IoT, Mobility, and Energy overwhelmingly favor Metadata-based efficiency. Furthermore, we explicitly distinguish ''Core CFL'' (grouping clients for non-IID data) from ''Clustered X FL'' (operational variants for system heterogeneity). Finally, we outline lessons learned and future directions to bridge the gap between theoretical privacy and practical efficiency.

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Michael Ben Ali, Omar El-Rifai, Imen Megdiche, André Peninou, Olivier Teste. 2025-01-29. A survey on Clustered Federated Learning: Taxonomy, Analysis and Applications. https://arxiv.org/abs/2501.17512

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