Federated Graph Augmentation for Semisupervised Node Classification

Semisupervised node classification is a prevalent task on graphs, which involves predicting the labels of unlabeled nodes based on limited labeled data available. At present, centralized approaches to training models for this task are unsustainable due to the increasing demand for computational power, storage capacity, and privacy. An approach of potential is federated graph learning (FGL), which allows multiple clients to collaborate on learning a model while maintaining data privacy. However, current methods suffer from the inability to consider the topology of the graph data and inadequate use of unlabeled data. To address these issues, we propose federated graph augmentation (FedGA) by combining graph neural network (GNN) models to utilize similar topologies existing in different client graphs and augment the client data. Furthermore, we develop FedGA-L based on FedGA, which integrates pseudolabeling and label-injection to improve the utilization of unlabeled data. FedGA-L allows pseudolabels to be used as additional information to enhance data augmentation and further improve the accuracy of node classification. We evaluate the effectiveness of FedGA and FedGA-L through experiments on multiple datasets. The results demonstrate improved accuracy in solving typical classification tasks and their compatibility with a variety of federated learning (FL) frameworks. On widely recognized datasets for graph learning, we achieve an accuracy improvement of 5%–7% compared to vanilla federated learning algorithms.