FlexFL: Heterogeneous Federated Learning via APoZ-Guided Flexible Pruning in Uncertain Scenarios

Along with the increasing popularity of deep learning (DL) techniques, more and more Artificial Intelligence of Things (AIoT) systems are adopting federated learning (FL) to enable privacy-aware collaborative learning among the AIoT devices. However, due to the inherent data and device heterogeneity issues, the existing FL-based AIoT systems suffer from the model selection problem. Although various heterogeneous FL methods have been investigated to enable collaborative training among the heterogeneous models, there is still a lack of 1) wise heterogeneous model generation methods for the devices; 2) consideration of uncertain factors; and 3) performance guarantee for the large models, thus strongly limiting the overall FL performance. To address the above issues, this article introduces a novel heterogeneous FL framework named FlexFL. By adopting our average percentage of zeros (APoZ)-guided flexible pruning strategy, FlexFL can effectively derive best-fit models for the heterogeneous devices to explore their greatest potential. Meanwhile, our proposed adaptive local pruning strategy allows the AIoT devices to prune their received models according to their varying resources within uncertain scenarios. Moreover, based on the self-knowledge distillation, FlexFL can enhance the inference performance of the large models by learning the knowledge from the small models. Comprehensive experimental results show that, compared to the state-of-the-art heterogeneous FL methods, FlexFL can significantly improve the overall inference accuracy by up to 14.24%. Our code can be found here https://github.com/mastlab-T3S/FlexFL.