FedScalar: Federated Learning with Scalar Communication for Bandwidth-Constrained Networks

Fuente: arXiv
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Main Authors: Rostami, M., Kia, S. S.
Format: Preprint
Published: 2024
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author Rostami, M.
Kia, S. S.
author_facet Rostami, M.
Kia, S. S.
contents In bandwidth-constrained federated learning~(FL) settings, the repeated upload of high-dimensional model updates from agents to a central server constitutes the primary bottleneck, often rendering standard FL infeasible within practical communication budgets. We propose \emph{FedScalar}, a communication-efficient FL algorithm in which each agent uploads only two scalar values per round, regardless of the model dimension~$d$. Each agent encodes its local update difference as an inner product with a locally generated random vector and transmits the resulting scalar together with the generating seed, enabling the server to reconstruct an unbiased gradient estimate without any high-dimensional transmission. We prove that \emph{FedScalar} achieves a convergence rate of $O(d/\sqrt{K})$ to a stationary point for smooth non-convex loss functions, and show that adopting a Rademacher distribution for the random vector reduces the aggregation variance compared to the Gaussian case. Numerical simulations confirm that the dimension-free upload cost translates into significant improvements in wall-clock time and energy efficiency over \emph{FedAvg} and \emph{QSGD} in bandwidth-constrained settings.
format Preprint
id arxiv_https___arxiv_org_abs_2410_02260
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle FedScalar: Federated Learning with Scalar Communication for Bandwidth-Constrained Networks
Rostami, M.
Kia, S. S.
Machine Learning
In bandwidth-constrained federated learning~(FL) settings, the repeated upload of high-dimensional model updates from agents to a central server constitutes the primary bottleneck, often rendering standard FL infeasible within practical communication budgets. We propose \emph{FedScalar}, a communication-efficient FL algorithm in which each agent uploads only two scalar values per round, regardless of the model dimension~$d$. Each agent encodes its local update difference as an inner product with a locally generated random vector and transmits the resulting scalar together with the generating seed, enabling the server to reconstruct an unbiased gradient estimate without any high-dimensional transmission. We prove that \emph{FedScalar} achieves a convergence rate of $O(d/\sqrt{K})$ to a stationary point for smooth non-convex loss functions, and show that adopting a Rademacher distribution for the random vector reduces the aggregation variance compared to the Gaussian case. Numerical simulations confirm that the dimension-free upload cost translates into significant improvements in wall-clock time and energy efficiency over \emph{FedAvg} and \emph{QSGD} in bandwidth-constrained settings.
title FedScalar: Federated Learning with Scalar Communication for Bandwidth-Constrained Networks
topic Machine Learning
url https://arxiv.org/abs/2410.02260