In-Context Learning for MIMO Equalization Using Transformer-Based Sequence Models

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Hauptverfasser: Zecchin, Matteo, Yu, Kai, Simeone, Osvaldo
Format: Preprint
Veröffentlicht: 2023
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author Zecchin, Matteo
Yu, Kai
Simeone, Osvaldo
author_facet Zecchin, Matteo
Yu, Kai
Simeone, Osvaldo
contents Large pre-trained sequence models, such as transformer-based architectures, have been recently shown to have the capacity to carry out in-context learning (ICL). In ICL, a decision on a new input is made via a direct mapping of the input and of a few examples from the given task, serving as the task's context, to the output variable. No explicit updates of the model parameters are needed to tailor the decision to a new task. Pre-training, which amounts to a form of meta-learning, is based on the observation of examples from several related tasks. Prior work has shown ICL capabilities for linear regression. In this study, we leverage ICL to address the inverse problem of multiple-input and multiple-output (MIMO) equalization based on a context given by pilot symbols. A task is defined by the unknown fading channel and by the signal-to-noise ratio (SNR) level, which may be known. To highlight the practical potential of the approach, we allow the presence of quantization of the received signals. We demonstrate via numerical results that transformer-based ICL has a threshold behavior, whereby, as the number of pre-training tasks grows, the performance switches from that of a minimum mean squared error (MMSE) equalizer with a prior determined by the pre-trained tasks to that of an MMSE equalizer with the true data-generating prior.
format Preprint
id arxiv_https___arxiv_org_abs_2311_06101
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle In-Context Learning for MIMO Equalization Using Transformer-Based Sequence Models
Zecchin, Matteo
Yu, Kai
Simeone, Osvaldo
Information Theory
Artificial Intelligence
Machine Learning
Large pre-trained sequence models, such as transformer-based architectures, have been recently shown to have the capacity to carry out in-context learning (ICL). In ICL, a decision on a new input is made via a direct mapping of the input and of a few examples from the given task, serving as the task's context, to the output variable. No explicit updates of the model parameters are needed to tailor the decision to a new task. Pre-training, which amounts to a form of meta-learning, is based on the observation of examples from several related tasks. Prior work has shown ICL capabilities for linear regression. In this study, we leverage ICL to address the inverse problem of multiple-input and multiple-output (MIMO) equalization based on a context given by pilot symbols. A task is defined by the unknown fading channel and by the signal-to-noise ratio (SNR) level, which may be known. To highlight the practical potential of the approach, we allow the presence of quantization of the received signals. We demonstrate via numerical results that transformer-based ICL has a threshold behavior, whereby, as the number of pre-training tasks grows, the performance switches from that of a minimum mean squared error (MMSE) equalizer with a prior determined by the pre-trained tasks to that of an MMSE equalizer with the true data-generating prior.
title In-Context Learning for MIMO Equalization Using Transformer-Based Sequence Models
topic Information Theory
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2311.06101