1,031 research outputs found
Federated learning over wireless fading channels
We study federated machine learning at the wirelessnetwork edge, where limited power wireless devices, each withits own dataset, build a joint model with the help of a remoteparameter server (PS). We consider a bandwidth-limited fadingmultiple access channel (MAC) from the wireless devices to thePS, and propose various techniques to implement distributedstochastic gradient descent (DSGD) over this shared noisywireless channel. We first propose a digital DSGD (D-DSGD)scheme, in which one device is selected opportunistically fortransmission at each iteration based on the channel conditions;the scheduled device quantizes its gradient estimate to a finitenumber of bits imposed by the channel condition, and transmitsthese bits to the PS in a reliable manner. Next, motivated bythe additive nature of the wireless MAC, we propose a novelanalog communication scheme, referred to as thecompressedanalogDSGD (CA-DSGD), where the devices first sparsifytheir gradient estimates while accumulating error from previousiterations, and project the resultant sparse vector into a low-dimensional vector for bandwidth reduction. We also design apower allocation scheme to align the received gradient vectorsat the PS in an efficient manner. Numerical results show thatD-DSGD outperforms other digital approaches in the literature;however, in general the proposed CA-DSGD algorithm convergesfaster than the D-DSGD scheme, and reaches a higher level ofaccuracy. We have observed that the gap between the analogand digital schemes increases when the datasets of devices arenot independent and identically distributed (i.i.d.). Furthermore,the performance of the CA-DSGD scheme is shown to be robustagainst imperfect channel state information (CSI) at the devices.Overall these results show clear advantages for the proposedanalog over-the-air DSGD scheme, which suggests that learningand communication algorithms should be designed jointly toachieve the best end-to-end performance in machine learningapplications at the wireless edge
Wireless Data Acquisition for Edge Learning: Data-Importance Aware Retransmission
By deploying machine-learning algorithms at the network edge, edge learning
can leverage the enormous real-time data generated by billions of mobile
devices to train AI models, which enable intelligent mobile applications. In
this emerging research area, one key direction is to efficiently utilize radio
resources for wireless data acquisition to minimize the latency of executing a
learning task at an edge server. Along this direction, we consider the specific
problem of retransmission decision in each communication round to ensure both
reliability and quantity of those training data for accelerating model
convergence. To solve the problem, a new retransmission protocol called
data-importance aware automatic-repeat-request (importance ARQ) is proposed.
Unlike the classic ARQ focusing merely on reliability, importance ARQ
selectively retransmits a data sample based on its uncertainty which helps
learning and can be measured using the model under training. Underpinning the
proposed protocol is a derived elegant communication-learning relation between
two corresponding metrics, i.e., signal-to-noise ratio (SNR) and data
uncertainty. This relation facilitates the design of a simple threshold based
policy for importance ARQ. The policy is first derived based on the classic
classifier model of support vector machine (SVM), where the uncertainty of a
data sample is measured by its distance to the decision boundary. The policy is
then extended to the more complex model of convolutional neural networks (CNN)
where data uncertainty is measured by entropy. Extensive experiments have been
conducted for both the SVM and CNN using real datasets with balanced and
imbalanced distributions. Experimental results demonstrate that importance ARQ
effectively copes with channel fading and noise in wireless data acquisition to
achieve faster model convergence than the conventional channel-aware ARQ.Comment: This is an updated version: 1) extension to general classifiers; 2)
consideration of imbalanced classification in the experiments. Submitted to
IEEE Journal for possible publicatio
Wireless for Machine Learning
As data generation increasingly takes place on devices without a wired
connection, Machine Learning over wireless networks becomes critical. Many
studies have shown that traditional wireless protocols are highly inefficient
or unsustainable to support Distributed Machine Learning. This is creating the
need for new wireless communication methods. In this survey, we give an
exhaustive review of the state of the art wireless methods that are
specifically designed to support Machine Learning services. Namely,
over-the-air computation and radio resource allocation optimized for Machine
Learning. In the over-the-air approach, multiple devices communicate
simultaneously over the same time slot and frequency band to exploit the
superposition property of wireless channels for gradient averaging
over-the-air. In radio resource allocation optimized for Machine Learning,
Active Learning metrics allow for data evaluation to greatly optimize the
assignment of radio resources. This paper gives a comprehensive introduction to
these methods, reviews the most important works, and highlights crucial open
problems.Comment: Corrected typo in author name. From the incorrect Maitron to the
correct Mairto
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