Collaborative learning between edge servers (e.g., base stations) and end devices (e.g., drones) enables simultaneous model training in web applications through knowledge sharing. The resulting models effectively reduce service latency. However, existing approaches either assume isomorphic models on edge servers and end devices or incur substantial transmission overhead when training. Moreover, edge servers are often unable to access data from end devices on time due to long-distance constraints or strict data privacy regulations. This paper proposes a Prototype Augmentation-based Edge-end Collaborative Learning method (PAECL). It simultaneously trains heterogeneous edge and end models in the absence of data on edge servers by transmitting only augmented class-wise feature vectors (prototypes), significantly reducing communication overhead compared to sharing models, data, or logits. Specifically, on end devices, prototype-implied latent knowledge is augmented via local prototype contrast and global prototype alignment. On edge servers, prototypes are further augmented to produce bounded virtual vectors by mixing them with random noise, and the augmented prototypes are then delivered to generative models to provide data during edge model training. Through simulations and field experiments, PAECL achieves the highest accuracy for edge and end models under limited training resources and reduces the transmission burden by at least 297 times compared to existing edge-end heterogeneous learning methods.

Edge-end collaborative learning trains models with exchanged knowledge through distributed interaction, alleviating the cloud's burden. Edge-end heterogeneous collaborative learning further enables edge servers and end devices to train models of different scales in parallel based on their computational capabilities. This technology supports various applications in different resource conditions and improves server resource utilization. However, implementing it is challenging due to heavy communication costs and high global costs (time and energy). To this end, this paper proposes a novel prototype-based edge-end heterogeneous collaborative learning method and an optimization algorithm, which improves model performance and reduces training costs. We first use prototypes to perform collaborative learning and analyze the convergence. Prototypes are computed as mean feature vectors from different classes. The aggregated prototypes help capture class information on end devices and generate data on edge servers. Then, we study how to determine prototype selection and edge association to minimize training time, energy consumption, and prototype approximation error under a limited reward budget, which is proven to be NP-hard. We split the original problem into two subproblems. The first is solved in the closed form. Through approximation and reformulation, the second is transformed into a submodular maximization problem with knapsack and matroid constraints. On this basis, we propose an approximation algorithm with a theoretical guarantee. Finally, by simulation and field experiments, our method takes 3.61% of communication costs to improve heterogeneous edge and end models' accuracy by at least 5.16% and 2.77% compared with five baselines. The proposed algorithm outperforms others by at least 9.78% in terms of global cost.

The use of unmanned aerial vehicles (UAVs) for long-range energy replenishment and data collection in wireless sensor networks (WSNs) across various scenarios seeks to minimize energy consumption by optimizing the scheduling and visiting sequence of the UAV’s hovering points. The problem can be modeled as a joint scheduling and trajectory optimization problem (JSTOP). To address the challenges posed by the limitations of the traditional JSTOP algorithm, we propose a multi-objective optimization algorithm-based joint scheduling and trajectory optimization scheme (MOJSTOP), which consists of two sub-algorithms, the improved multi-objective simulated annealing algorithm (Improved MSA) and the improved non-dominated sorting genetic algorithm II (Improved NSGA-II). The Improved MSA algorithm is well-suited for small-scale scenarios. In contrast, the Improved NSGA-II algorithm is designed for large-scale scenarios where the UAV has limited energy capacity. In addition, it introduces a new optimization objective that focuses on the energy utilization efficiency of the UAV. The simulation results demonstrate that the proposed MOJSTOP scheme exhibits superior computational efficiency, convergence, and stability in solving the JSTOP problem compared to other algorithms and is applicable to various terrains.

Edge-end collaborative learning greatly reduces latency by eliminating the need for processing on the cloud side, showing promising results in machine learning applications due to collaborating on training tasks through the computational resources of edge servers and end devices. However, current edge-end collaborative learning methods suffer from unbearable latency which result from heavy transmission burden and long synchronization time. We propose a new Prototype-based Semi-Asynchronous Edge-end Collaborative Learning approach (ProSACL) that carefully integrates prototype-based end-side training and edge clustering, allowing any end device to synchronize knowledge, significantly reducing the time spent on training latency. Our approach includes (1) prototype training and asynchronous prototype transfer on end devices: Unlike traditional training methods, we use the average of the same class of feature vectors, i.e., the prototype, as the knowledge transfer means, which significantly reduces the transfer burden and eliminates the need for end devices to wait for other devices to finish. (2) prototype-based clustering and asynchronous aggregation on the edge server: The end devices are segmented by prototype-based clustering to obtain unbiased prototypes for performance enhancement, and prototypes from different rounds are aggregated for fine-grained knowledge transfer. We evaluate the proposed approach by training on three datasets, which show substantial performance improvement compared to previous work.