While the application of differential privacy (DP) has been well-studied in cross-device federated learning (FL), there is a lack of work considering DP for cross-silo FL, a setting characterized by a limited number of clients each containing many data subjects. In cross-silo FL, usual notions of client-level privacy are less suitable as real-world privacy regulations typically concern in-silo data subjects rather than the silos themselves. In this work, we instead consider the more realistic notion of silo-specific item-level privacy, where silos set their own privacy targets for their local examples. Under this setting, we reconsider the roles of personalization in federated learning. In particular, we show that mean-regularized multi-task learning (MR-MTL), a simple personalization framework, is a strong baseline for cross-silo FL: under stronger privacy, silos are further incentivized to "federate" with each other to mitigate DP noise, resulting in consistent improvements relative to standard baseline methods. We provide a thorough empirical study of competing methods as well as a theoretical characterization of MR-MTL for a mean estimation problem, highlighting the interplay between privacy and cross-silo data heterogeneity. Our work serves to establish baselines for private cross-silo FL as well as identify key directions of future work in this area.

本研究探讨了分布式学习中的隐私保护问题，在特定的跨场景环境下，提出了基于局部数据交叉学习的个性化学习框架，并给出了实验证明其在隐私保护和数据异质性之间的平衡效果。

关于跨资源联邦学习中的隐私和个性化