  Realistic synthetic tabular data generation encounters significant challenges
in preserving privacy, especially when dealing with sensitive information in
domains like finance and healthcare. In this paper, we introduce
\textit{Federated Tabular Diffusion} (FedTabDiff) for generating high-fidelity
mixed-type tabular data without centralized access to the original tabular
datasets. Leveraging the strengths of \textit{Denoising Diffusion Probabilistic
Models} (DDPMs), our approach addresses the inherent complexities in tabular
data, such as mixed attribute types and implicit relationships. More
critically, FedTabDiff realizes a decentralized learning scheme that permits
multiple entities to collaboratively train a generative model while respecting
data privacy and locality. We extend DDPMs into the federated setting for
tabular data generation, which includes a synchronous update scheme and
weighted averaging for effective model aggregation. Experimental evaluations on
real-world financial and medical datasets attest to the framework's capability
to produce synthetic data that maintains high fidelity, utility, privacy, and
coverage.
