Adaptive Heterogeneous Client Sampling for Federated Learning over Wireless Networks

Fuente: arXiv
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Main Authors: Luo, Bing, Xiao, Wenli, Wang, Shiqiang, Huang, Jianwei, Tassiulas, Leandros
Format: Preprint
Published: 2024
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author Luo, Bing
Xiao, Wenli
Wang, Shiqiang
Huang, Jianwei
Tassiulas, Leandros
author_facet Luo, Bing
Xiao, Wenli
Wang, Shiqiang
Huang, Jianwei
Tassiulas, Leandros
contents Federated learning (FL) algorithms usually sample a fraction of clients in each round (partial participation) when the number of participants is large and the server's communication bandwidth is limited. Recent works on the convergence analysis of FL have focused on unbiased client sampling, e.g., sampling uniformly at random, which suffers from slow wall-clock time for convergence due to high degrees of system heterogeneity and statistical heterogeneity. This paper aims to design an adaptive client sampling algorithm for FL over wireless networks that tackles both system and statistical heterogeneity to minimize the wall-clock convergence time. We obtain a new tractable convergence bound for FL algorithms with arbitrary client sampling probability. Based on the bound, we analytically establish the relationship between the total learning time and sampling probability with an adaptive bandwidth allocation scheme, which results in a non-convex optimization problem. We design an efficient algorithm for learning the unknown parameters in the convergence bound and develop a low-complexity algorithm to approximately solve the non-convex problem. Our solution reveals the impact of system and statistical heterogeneity parameters on the optimal client sampling design. Moreover, our solution shows that as the number of sampled clients increases, the total convergence time first decreases and then increases because a larger sampling number reduces the number of rounds for convergence but results in a longer expected time per-round due to limited wireless bandwidth. Experimental results from both hardware prototype and simulation demonstrate that our proposed sampling scheme significantly reduces the convergence time compared to several baseline sampling schemes.
format Preprint
id arxiv_https___arxiv_org_abs_2404_13804
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Adaptive Heterogeneous Client Sampling for Federated Learning over Wireless Networks
Luo, Bing
Xiao, Wenli
Wang, Shiqiang
Huang, Jianwei
Tassiulas, Leandros
Distributed, Parallel, and Cluster Computing
Machine Learning
Networking and Internet Architecture
Systems and Control
Federated learning (FL) algorithms usually sample a fraction of clients in each round (partial participation) when the number of participants is large and the server's communication bandwidth is limited. Recent works on the convergence analysis of FL have focused on unbiased client sampling, e.g., sampling uniformly at random, which suffers from slow wall-clock time for convergence due to high degrees of system heterogeneity and statistical heterogeneity. This paper aims to design an adaptive client sampling algorithm for FL over wireless networks that tackles both system and statistical heterogeneity to minimize the wall-clock convergence time. We obtain a new tractable convergence bound for FL algorithms with arbitrary client sampling probability. Based on the bound, we analytically establish the relationship between the total learning time and sampling probability with an adaptive bandwidth allocation scheme, which results in a non-convex optimization problem. We design an efficient algorithm for learning the unknown parameters in the convergence bound and develop a low-complexity algorithm to approximately solve the non-convex problem. Our solution reveals the impact of system and statistical heterogeneity parameters on the optimal client sampling design. Moreover, our solution shows that as the number of sampled clients increases, the total convergence time first decreases and then increases because a larger sampling number reduces the number of rounds for convergence but results in a longer expected time per-round due to limited wireless bandwidth. Experimental results from both hardware prototype and simulation demonstrate that our proposed sampling scheme significantly reduces the convergence time compared to several baseline sampling schemes.
title Adaptive Heterogeneous Client Sampling for Federated Learning over Wireless Networks
topic Distributed, Parallel, and Cluster Computing
Machine Learning
Networking and Internet Architecture
Systems and Control
url https://arxiv.org/abs/2404.13804