Improving Federated Domain Generalization Through Dynamical Weights Calculated from Data Influences on Global Model Update

With the popularity of federated learning, federated domain generalization (FedDG) has attracted more and more attentions. Existing works of federated learning indicate that the generalization performance of the global model can be improved when the global model is obtained by aggregating local models according to a suitable weights. However, the existing methods to calculate weights do not fully utilize the data influences on the global model update, which gives us an opportunity to improve the generalization performance of the global model further. In this paper, we propose the method DI (data influences), which utilizes the data influences on the global model update to calculate dynamical weights of local model in each round of training. Specifically, the first component data influences calculator (DIC) of DI calculates the local weights of local model from the influences of each data on the global model update and we introduce the influences function to complete the calculation process. The second component data influences adjuster (DIA) of DI calculates the global weights (which are used in the aggregation process of the global model) from local weights. Extensive experiments indicate that our method improves the generalization performance of models significantly. In particular, our method improves model accuracy on benchmark datasets PACS, OfficeHome, and Office-31 by 1.79%, 1.61%, and 2.39% on average, respectively. Source code is publicly available at github.