Improving Federated Learning Performance by Leveraging Client Data Diversity

Core Concepts

Clients with more diverse data can improve the performance of federated learning models. By emphasizing updates from high-diversity clients and diminishing the influence of low-diversity clients, the proposed WeiAvgCS framework can significantly improve the convergence speed of federated learning.

Abstract

The paper proposes a novel approach called Weighted Federated Averaging and Client Selection (WeiAvgCS) to address the issue of data heterogeneity and diversity in federated learning (FL). The key insights are: Clients with more diverse data can improve the performance of the federated learning model. The diversity of a client's data is quantified by the variance of the label distribution. To mitigate privacy concerns, the paper introduces an estimation of data diversity using a projection-based method, which has a strong correlation with the actual variance. WeiAvgCS assigns higher weights to updates from high-diversity clients and retains them to participate in more rounds of training. This emphasizes the influence of high-diversity clients and diminishes the impact of low-diversity clients. Extensive experiments on FashionMNIST and CIFAR10 datasets demonstrate the effectiveness of WeiAvgCS. It can converge 46% faster on FashionMNIST and 38% faster on CIFAR10 than its benchmarks on average. WeiAvgCS is orthogonal to other state-of-the-art algorithms like FedProx, MOON, and Scaffold, and can be combined with them to further improve performance. The paper also identifies limitations of WeiAvgCS, where the correlation between projection and variance decreases under severe under-fitting, leading to poorer performance compared to FedAvg.

Stats

The paper does not provide any specific numerical data or statistics in the main text. The experimental results are presented in the form of accuracy plots and comparison tables.

Quotes

The paper does not contain any direct quotes that are particularly striking or support the key arguments.

Key Insights Distilled From

Federated Learning Model Aggregation in Heterogenous Aerial and Space Networks

by Fan Dong,Ali... at arxiv.org 04-11-2024

https://arxiv.org/pdf/2305.16351.pdf

Deeper Inquiries

What other metrics besides label distribution variance could be used to quantify the diversity of client data in federated learning

In federated learning, besides label distribution variance, other metrics can be used to quantify the diversity of client data. One such metric is the entropy of the data distribution on each client. Entropy measures the uncertainty or randomness in the data distribution, providing insight into the diversity of the data. Clients with higher entropy values would have more diverse data compared to those with lower entropy values. By considering entropy along with label distribution variance, a more comprehensive understanding of the diversity of client data can be obtained. Additionally, metrics like the Gini coefficient or the Shannon diversity index can also be utilized to quantify the diversity of client data in federated learning settings.

How can the WeiAvgCS algorithm be further improved to maintain its effectiveness even when the correlation between projection and variance is low due to under-fitting

To enhance the effectiveness of the WeiAvgCS algorithm when the correlation between projection and variance is low due to under-fitting, several strategies can be implemented. One approach is to incorporate regularization techniques during the local training phase to prevent overfitting and ensure that the local models capture the underlying patterns in the data effectively. By encouraging the local models to generalize well, the correlation between projection and variance can be strengthened, leading to improved performance of WeiAvgCS. Additionally, increasing the complexity of the model used in the algorithm or adjusting the hyperparameters related to the weighting scheme based on diversity could help mitigate the impact of under-fitting on the algorithm's performance.

How can the proposed approach be extended to handle non-i.i.d. data distributions beyond just label diversity, such as feature distribution heterogeneity

To extend the proposed approach to handle non-i.i.d. data distributions beyond just label diversity, such as feature distribution heterogeneity, a multi-faceted diversity assessment framework can be developed. This framework could incorporate metrics that evaluate the diversity of features, data distributions, and data characteristics across clients. For example, clustering algorithms can be employed to identify groups of clients with similar feature distributions, allowing for targeted client selection and weighted averaging based on feature diversity. Additionally, techniques from transfer learning and domain adaptation can be leveraged to align feature distributions across clients, reducing the impact of feature heterogeneity on federated learning performance. By integrating a holistic approach to diversity assessment that considers both label and feature distributions, the proposed approach can be extended to handle a wider range of non-i.i.d. data distributions in federated learning scenarios.