Relaxed Contrastive Learning for Federated Learning
This addresses data heterogeneity for federated learning systems, offering a novel method to enhance collaborative training.
The paper tackles data heterogeneity in federated learning by proposing a relaxed contrastive learning framework that prevents representation collapse, resulting in significant performance improvements over existing methods on standard benchmarks.
We propose a novel contrastive learning framework to effectively address the challenges of data heterogeneity in federated learning. We first analyze the inconsistency of gradient updates across clients during local training and establish its dependence on the distribution of feature representations, leading to the derivation of the supervised contrastive learning (SCL) objective to mitigate local deviations. In addition, we show that a naïve adoption of SCL in federated learning leads to representation collapse, resulting in slow convergence and limited performance gains. To address this issue, we introduce a relaxed contrastive learning loss that imposes a divergence penalty on excessively similar sample pairs within each class. This strategy prevents collapsed representations and enhances feature transferability, facilitating collaborative training and leading to significant performance improvements. Our framework outperforms all existing federated learning approaches by huge margins on the standard benchmarks through extensive experimental results.