Energy-Efficient Distributed Machine Learning at Wireless Edge with Device-to-Device Communication

This paper considers a federated edge learning (FEL) system where a base station (BS) coordinates a set of edge devices to train a shared machine learning model collaboratively. One of the fundamental issues in such systems is maintaining the learning performance with the limited and heterogeneous resource capabilities of edge devices. Our goal is to improve the energy efficiency of edge devices in FEL by mitigating the temporal and spatial heterogeneity of their energy resources. Specifically, to balance the heterogeneous energy levels among edge devices, energy-hungry devices can offload their data to nearby devices that have sufficient energy via device-to-device (D2D) communication links at low transmission overheads. Besides, to mitigate the impact of the time-varying energy level of a device, data collected by edge devices can be queued to be processed when sufficient energy is available. To compute the optimal offloading and queuing strategies, we propose an online control algorithm based on Lyapunov optimization to determine the amount of data to be offloaded, queued, and processed at each time slot. Our simulation results on the real-world dataset demonstrate that our approach achieves a better overall energy efficiency than baselines.