Federated Learning (FL) is a newly emerged decentralized machine learning (ML) framework that combines on-device local training with server-based model synchronization to train a centralized ML model over distributed nodes. In this paper, we propose an asynchronous FL framework with periodic aggregation to eliminate the straggler issue in FL systems. For the proposed model, we investigate several device scheduling and update aggregation policies and compare their performances when the devices have heterogeneous computation capabilities and training data distributions. From the simulation results, we conclude that the scheduling and aggregation design for asynchronous FL can be rather different from the synchronous case. For example, a norm-based significance-aware scheduling policy might not be efficient in an asynchronous FL setting, and an appropriate "age-aware" weighting design for the model aggregation can greatly improve the learning performance of such systems.

本文提出了一种异步FL框架，其采用定期聚合的方式消除了FL系统中的问题，并设计出多种装置调度和更新聚合策略以解决异构计算能力和训练数据分布的设备问题。通过模拟结果，我们得出结论，异步FL的调度和聚合设计可以不同于同步情况，并且适当的“年龄感知”加权设计可以极大地提高此类系统的学习性能。

异步联邦学习的设备调度和更新聚合策略