Understanding Server-Assisted Federated Learning in the Presence of Incomplete Client Participation
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Abstract (arXiv)
Existing works in federated learning (FL) often assume an ideal system with either full client or uniformly distributed client participation. However, in practice, it has been observed that some clients may never participate in FL training (aka incomplete client participation) due to a myriad of system heterogeneity factors. A popular approach to mitigate impacts of incomplete client participation is the server-assisted federated learning (SA-FL) framework, where the server is equipped with an auxiliary dataset. However, despite SA-FL has been empirically shown to be effective in addressing the incomplete client participation problem, there remains a lack of theoretical understanding for SA-FL. Meanwhile, the ramifications of incomplete client participation in conventional FL are also poorly understood. These theoretical gaps motivate us to rigorously investigate SA-FL. Toward this end, we first show that conventional FL is em not PAC-learnable under incomplete client participation in the worst case. Then, we show that the PAC-learnability of FL with incomplete client participation can indeed be revived by SA-FL, which theoretically justifies the use of SA-FL for the first time. Lastly, to provide practical guidance for SA-FL training under em incomplete client participation, we propose the mathsfSAFARI (server-assisted federated averaging) algorithm that enjoys the same linear convergence speedup guarantees as classic FL with ideal client participation assumptions, offering the first SA-FL algorithm with convergence guarantee. Extensive experiments on different datasets show mathsfSAFARI significantly improves the performance under incomplete client participation.
Key facts. Cited by 3 papers in the map (data through 7 Oct 2026). Builds on 33 of its 55 references that are in the map. First posted on arXiv 4 May 2024.
Builds on
33 of 55 references.
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Built on by
Citing papers per year: 2025: 1; 2026: 2.
3 papers.
- 2026BiCoLoR: Communication-Efficient Optimization with Bidirectional Compression and Local Trainingcited by 1
- 2025Overcoming Challenges of Partial Client Participation in Federated Learning : A Comprehensive Reviewcited by 0
- 2026FedLBW: A Loss-Based Weighting Strategy for Federated Learning on Non-IID Data in Wireless Networkscited by 0
- 2026FedLBW: A Loss-Based Weighting Strategy for Federated Learning on Non-IID Data in Wireless Networks7 Aug 2026
- 2026BiCoLoR: Communication-Efficient Optimization with Bidirectional Compression and Local Training18 Jan 2026
- 2025Overcoming Challenges of Partial Client Participation in Federated Learning : A Comprehensive Review3 Jun 2025