Advanced Relay-Based Collaborative Framework for Optimizing Synchronization in Split Federated Learning over Wireless Networks

Split Federated Learning (SFL) offers a promising approach for distributed model training in edge computing, combining the strengths of split learning in reducing computational demands on edge devices and enhancing data privacy, with the role of federated aggregation to ensure model convergence and synchronization across users. However, synchronization issues caused by user heterogeneity have hindered the development of the framework. To optimize synchronization efficiency among users and improve overall system performance, we propose a collaborative SFL framework (CSFL). Based on the model's partitioning capabilities, we design a mechanism called the collaborative relay optimization mechanism (CROM), where the assistance provided by high-efficiency users is seen as a relay process, with the portion of the model they compute acting as the relay point. Wireless communication between users facilitates real-time collaboration, allowing high-efficiency users to assist bottleneck users in handling part of the model's computation, thereby alleviating the computational load on bottleneck users. Simulation results show that our proposed CSFL framework reduces synchronization delays and improves overall system throughput while maintaining similar performance and convergence rate to the SFL framework. This demonstrates that the collaboration not only reduces synchronization waiting time but also accelerates model convergence.