FLHetBench: Benchmarking Device and State Heterogeneity in Federated Learning

Federated learning (FL) is a powerful technology that enables collaborative training of machine learning models without sharing private data among clients. The fundamental challenge in FL lies in learning over extremely hetero-geneous data distributions, device capacities, and device state availabilities, all of which adversely impact performance and communication efficiency. While data hetero-geneity has been well-studied in the literature, this paper introduces FLHetBench, the first FL benchmark targeted toward understanding device and state heterogeneity. FL-HetBench comprises two new sampling methods to generate real-world device and state databases with varying het-erogeneity and new metrics for quantifying the success of FL methods under these real-world constraints. Using FL-HetBench, we conduct a comprehensive evaluation of existing methods and find that they struggle under these settings, which inspires us to propose BiasPrompt+, a new method employing staleness-aware aggregation and fast weights to tackle these new heterogeneity challenges. Experiments on various FL tasks and datasets validate the effectiveness of our BiasPrompt+ method and highlight the value of FLHet-Bench in fostering the development of more efficient and robust FL solutions under real-world device and state constraints.