Stable Diffusion-based Data Augmentation for Federated Learning with Non-IID Data
Mahdi Morafah, Matthias Reisser, Bill Lin, Christos Louizos
TL;DR
This paper tackles the non IID data challenge in Federated Learning by introducing Gen-FedSD, a diffusion-based data augmentation approach. Each client generates class-specific prompts and uses a pre-trained Stable Diffusion model to synthesize data that fills local distribution gaps, resulting in locally augmented IID-like datasets prior to FL training. Empirical results on CIFAR-10 and CIFAR-100 show substantial gains in accuracy and faster convergence across multiple FL baselines, with pronounced improvements under higher heterogeneity and notable reductions in communication cost. The method offers practical privacy-preserving IID data augmentation by performing synthesis locally, and its effectiveness scales with prompt diversity and the quality of the diffusion model.
Abstract
The proliferation of edge devices has brought Federated Learning (FL) to the forefront as a promising paradigm for decentralized and collaborative model training while preserving the privacy of clients' data. However, FL struggles with a significant performance reduction and poor convergence when confronted with Non-Independent and Identically Distributed (Non-IID) data distributions among participating clients. While previous efforts, such as client drift mitigation and advanced server-side model fusion techniques, have shown some success in addressing this challenge, they often overlook the root cause of the performance reduction - the absence of identical data accurately mirroring the global data distribution among clients. In this paper, we introduce Gen-FedSD, a novel approach that harnesses the powerful capability of state-of-the-art text-to-image foundation models to bridge the significant Non-IID performance gaps in FL. In Gen-FedSD, each client constructs textual prompts for each class label and leverages an off-the-shelf state-of-the-art pre-trained Stable Diffusion model to synthesize high-quality data samples. The generated synthetic data is tailored to each client's unique local data gaps and distribution disparities, effectively making the final augmented local data IID. Through extensive experimentation, we demonstrate that Gen-FedSD achieves state-of-the-art performance and significant communication cost savings across various datasets and Non-IID settings.
