Transfer Learning Autoencoder for CSI Compression

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Solution Overview

Problem

Existing autoencoder solutions struggle to generalize to diverse channel distributions, requiring retraining for specific deployment scenarios and necessitating the reconfiguration of user equipment (UE) with scenario-specific encoders, which involves significant signaling effort.

Innovation Solution

The method employs transfer learning to pre-train an autoencoder's encoder on synthetic channel data, freezing its weights, and then retraining the decoder on real measured channel data, allowing the autoencoder to adapt to specific deployment scenarios without changing the encoder weights, thus avoiding the need for explicit signaling of new encoder weights.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the autoencoder is retrained for specific deployment scenarios to improve generalization performance, then the CSI compression performance is improved, but the signaling overhead increases due to the need to reconfigure UE with scenario-specific encoders

Engineering Contradiction:
ImproveCSI compression performanceVSAvoidsignaling overhead
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

The patent segments the autoencoder into two independent components: an encoder that remains fixed and a decoder that is retrained for specific scenarios. This segmentation allows the encoder to be standardized and reused across all deployment scenarios, while only the scenario-specific decoder needs to be updated, thereby reducing signaling overhead while maintaining compression performance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The encoder is pre-trained on synthetic channel data in advance and its weights are frozen before deployment. This preliminary action allows the encoder to learn general compression features that are applicable across different scenarios, eliminating the need to retransmit encoder weights for each scenario and reducing signaling overhead.

Inventive Principle:
Principle #10Preliminary action

2Adaptability or versatility

If the encoder weights are reconfigured for different deployment scenarios to improve adaptability, then the model accuracy is improved, but the device complexity increases due to multiple scenario-specific encoders

Engineering Contradiction:
Improvescenario adaptabilityVSAvoidencoder configuration complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent makes the encoder universal by training it on synthetic channel data that encompasses multiple deployment scenarios. The frozen encoder weights enable a single encoder implementation to serve multiple functions across different scenarios, eliminating the need for multiple scenario-specific encoder configurations and reducing device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Measurement precision

If the autoencoder is jointly retrained for specific scenarios to improve compression accuracy, then the CSI resolution is improved, but the training time and resources increase

Engineering Contradiction:
ImproveCSI resolutionVSAvoidtraining time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The encoder is pre-trained on synthetic channel data in advance, performing the time-consuming training operation beforehand. This preliminary action separates the general compression feature learning (done once) from the scenario-specific adaptation (done quickly by retraining only the decoder), thereby reducing the time required for scenario-specific deployment.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS20240202542A1Methods for transfer learning in CSI-compression
Publication Date: 2024.06.20 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • US20240202542A1 patent drawing
  • US20240202542A1 patent drawing
  • US20240202542A1 patent drawing

AI summary

According to an aspect, there is provided a method of training an autoencoder in a target domain. The autoencoder includes a first neural network encoder for use in a wireless device and a first neural network decoder for use in a base station. The method includes: obtaining a first set of weights; training a second neural network encoder in a source domain using a first data set to determine a first set of weights, wherein the second neural network encoder has the same structure as the first neural network encoder; setting weights of the first neural network encoder to the first set of weights; and training the first neural network decoder using a second data set, during which the weights of the first neural network encoder are fixed.