Wireless Federated Multi-Task LLM Fine-Tuning via Sparse-and-Orthogonal LoRA

Fuente: arXiv
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Main Authors: Yang, Nuocheng, Wang, Sihua, Huan, Ouwen, Chen, Mingzhe, Quek, Tony Q. S., Yin, Changchuan
Format: Preprint
Published: 2026
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_version_ 1866912922946502656
author Yang, Nuocheng
Wang, Sihua
Huan, Ouwen
Chen, Mingzhe
Quek, Tony Q. S.
Yin, Changchuan
author_facet Yang, Nuocheng
Wang, Sihua
Huan, Ouwen
Chen, Mingzhe
Quek, Tony Q. S.
Yin, Changchuan
contents Decentralized federated learning (DFL) based on low-rank adaptation (LoRA) enables mobile devices with multi-task datasets to collaboratively fine-tune a large language model (LLM) by exchanging locally updated parameters with a subset of neighboring devices via wireless connections for knowledge integration.However, directly aggregating parameters fine-tuned on heterogeneous datasets induces three primary issues across the DFL life-cycle: (i) \textit{catastrophic knowledge forgetting during fine-tuning process}, arising from conflicting update directions caused by data heterogeneity; (ii) \textit{inefficient communication and convergence during model aggregation process}, due to bandwidth-intensive redundant model transmissions; and (iii) \textit{multi-task knowledge interference during inference process}, resulting from incompatible knowledge representations coexistence during inference. To address these issues in a fully decentralized scenario, we first propose a sparse-and-orthogonal LoRA that ensures orthogonality between model updates to eliminate direction conflicts during fine-tuning.Then, we analyze how device connection topology affects multi-task performance, prompting a cluster-based topology design during aggregation.Finally, we propose an implicit mixture of experts (MoE) mechanism to avoid the coexistence of incompatible knowledge during inference. Simulation results demonstrate that the proposed approach effectively reduces communication resource consumption by up to $73\%$ and enhances average performance by $5\%$ compared with the traditional LoRA method.
format Preprint
id arxiv_https___arxiv_org_abs_2602_20492
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Wireless Federated Multi-Task LLM Fine-Tuning via Sparse-and-Orthogonal LoRA
Yang, Nuocheng
Wang, Sihua
Huan, Ouwen
Chen, Mingzhe
Quek, Tony Q. S.
Yin, Changchuan
Machine Learning
Artificial Intelligence
Decentralized federated learning (DFL) based on low-rank adaptation (LoRA) enables mobile devices with multi-task datasets to collaboratively fine-tune a large language model (LLM) by exchanging locally updated parameters with a subset of neighboring devices via wireless connections for knowledge integration.However, directly aggregating parameters fine-tuned on heterogeneous datasets induces three primary issues across the DFL life-cycle: (i) \textit{catastrophic knowledge forgetting during fine-tuning process}, arising from conflicting update directions caused by data heterogeneity; (ii) \textit{inefficient communication and convergence during model aggregation process}, due to bandwidth-intensive redundant model transmissions; and (iii) \textit{multi-task knowledge interference during inference process}, resulting from incompatible knowledge representations coexistence during inference. To address these issues in a fully decentralized scenario, we first propose a sparse-and-orthogonal LoRA that ensures orthogonality between model updates to eliminate direction conflicts during fine-tuning.Then, we analyze how device connection topology affects multi-task performance, prompting a cluster-based topology design during aggregation.Finally, we propose an implicit mixture of experts (MoE) mechanism to avoid the coexistence of incompatible knowledge during inference. Simulation results demonstrate that the proposed approach effectively reduces communication resource consumption by up to $73\%$ and enhances average performance by $5\%$ compared with the traditional LoRA method.
title Wireless Federated Multi-Task LLM Fine-Tuning via Sparse-and-Orthogonal LoRA
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2602.20492