Asynchronous Decentralized Federated Learning for Heterogeneous Devices

Data generated at the network edge can be processed locally by leveraging the emerging technology of Federated Learning (FL). However, non-IID local data will lead to degradation of model accuracy and the heterogeneity of edge nodes inevitably slows down model training efficiency. Moreover, to avoid the potential communication bottleneck in the parameter-server-based FL, we concentrate on the Decentralized Federated Learning (DFL) that performs distributed model training in Peer-to-Peer (P2P) manner. To address these challenges, we propose an asynchronous DFL system by incorporating neighbor selection and gradient push, termed AsyDFL. Specifically, we require each edge node to push gradients only to a subset of neighbors for resource efficiency. Herein, we first give a theoretical convergence analysis of AsyDFL under the complicated non-IID and heterogeneous scenario, and further design a priority-based algorithm to dynamically select neighbors for each edge node so as to achieve the trade-off between communication cost and model performance. We evaluate the performance of AsyDFL through extensive experiments on a physical platform with 30 NVIDIA Jetson edge devices. Evaluation results show that AsyDFL can reduce the communication cost by 57% and the completion time by about 35% for achieving the same test accuracy, and improve model accuracy by at least 6% under the non-IID scenario, compared to the baselines.