Improving Wireless Federated Learning via Joint Downlink-Uplink Beamforming over Analog Transmission

Fuente: arXiv
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Hauptverfasser: Zhang, Chong, Dong, Min, Liang, Ben, Afana, Ali, Ahmed, Yahia
Format: Preprint
Veröffentlicht: 2025
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author Zhang, Chong
Dong, Min
Liang, Ben
Afana, Ali
Ahmed, Yahia
author_facet Zhang, Chong
Dong, Min
Liang, Ben
Afana, Ali
Ahmed, Yahia
contents Federated learning (FL) over wireless networks using analog transmission can efficiently utilize the communication resource but is susceptible to errors caused by noisy wireless links. In this paper, assuming a multi-antenna base station, we jointly design downlink-uplink beamforming to maximize FL training convergence over time-varying wireless channels. We derive the round-trip model updating equation and use it to analyze the FL training convergence to capture the effects of downlink and uplink beamforming and the local model training on the global model update. Aiming to maximize the FL training convergence rate, we propose a low-complexity joint downlink-uplink beamforming (JDUBF) algorithm, which adopts a greedy approach to decompose the multi-round joint optimization and convert it into per-round online joint optimization problems. The per-round problem is further decomposed into three subproblems over a block coordinate descent framework, where we show that each subproblem can be efficiently solved by projected gradient descent with fast closed-form updates. An efficient initialization method that leads to a closed-form initial point is also proposed to accelerate the convergence of JDUBF. Simulation demonstrates that JDUBF substantially outperforms the conventional separate-link beamforming design.
format Preprint
id arxiv_https___arxiv_org_abs_2502_02034
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Improving Wireless Federated Learning via Joint Downlink-Uplink Beamforming over Analog Transmission
Zhang, Chong
Dong, Min
Liang, Ben
Afana, Ali
Ahmed, Yahia
Information Theory
Signal Processing
Federated learning (FL) over wireless networks using analog transmission can efficiently utilize the communication resource but is susceptible to errors caused by noisy wireless links. In this paper, assuming a multi-antenna base station, we jointly design downlink-uplink beamforming to maximize FL training convergence over time-varying wireless channels. We derive the round-trip model updating equation and use it to analyze the FL training convergence to capture the effects of downlink and uplink beamforming and the local model training on the global model update. Aiming to maximize the FL training convergence rate, we propose a low-complexity joint downlink-uplink beamforming (JDUBF) algorithm, which adopts a greedy approach to decompose the multi-round joint optimization and convert it into per-round online joint optimization problems. The per-round problem is further decomposed into three subproblems over a block coordinate descent framework, where we show that each subproblem can be efficiently solved by projected gradient descent with fast closed-form updates. An efficient initialization method that leads to a closed-form initial point is also proposed to accelerate the convergence of JDUBF. Simulation demonstrates that JDUBF substantially outperforms the conventional separate-link beamforming design.
title Improving Wireless Federated Learning via Joint Downlink-Uplink Beamforming over Analog Transmission
topic Information Theory
Signal Processing
url https://arxiv.org/abs/2502.02034