Federated Domain Generalization with Data-free On-server Matching Gradient

Trong Binh Nguyen, Duong Minh Nguyen, Jinsun Park, Viet Quoc Pham, Won-Joo Hwang

Keywords: Federated Learning, Domain Generalization

TL;DR: The paper propose a on-server approach to aggregate clients' informations and statistics without the data transmissions from clients to solve the federated domain generalization

Abstract: Domain Generalization (DG) aims to learn from multiple known source domains a model that can generalize well to unknown target domains. One of the key approaches in DG is training an encoder which generates domain-invariant representations. However, this approach is not applicable in Federated Domain Generalization (FDG), where data from various domains are distributed across different clients. In this paper, we introduce a novel approach, dubbed Federated Learning via On-server Matching Gradient (FedOMG), which can efficiently leverage domain information from distributed domains. Specifically, we utilize the local gradients as information about the distributed models to find an invariant gradient direction across all domains through gradient inner product maximization. The advantages are two-fold: 1) FedOMG can aggregate the characteristics of distributed models on the centralized server without incurring any additional communication cost, and 2) FedOMG is orthogonal to many existing FL/FDG methods, allowing for additional performance improvements by being seamlessly integrated with them. Extensive experimental evaluations on various settings demonstrate the robustness of FedOMG compared to other FL/FDG baselines. Our method outperforms recent SOTA baselines on four FL benchmark datasets (MNIST, EMNIST, CIFAR-10, and CIFAR-100), and three FDG benchmark datasets (PACS, VLCS, and OfficeHome). The reproducible code is publicly available~\footnote[1]{\url{https://github.com/skydvn/fedomg}}.

Primary Area: other topics in machine learning (i.e., none of the above)

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Submission Number: 9130