Fingerprint Extraction Through Distortion Reconstruction (FEDR): A CNN-Based Approach to RF Fingerprinting

Radio Frequency Fingerprinting (RFF) is the attribution of uniquely identifiable signal distortions to emitters via Machine Learning (ML) classifiers. RFF approaches relying on pre-determined expert features lack generalizability, and state-of-the-art approaches based on Convolutional Neural Networks (CNNs) can be too demanding for endpoint devices to train. This work presents Fingerprint Extraction through Distortion Reconstruction (FEDR), a best-of-both-worlds technique which employs a pre-trained CNN to identify and extract a small, salient set of unique features, amenable for use in lightweight machine learning models. Given a received distorted signal, the FEDR network encodes signal distortions into “fingerprints,” which can be used by lightweight ML classifiers to perform RFF with minimal resource consumption at the endpoint. FEDR learns by transforming generated signals into reconstructions of received signals, relying solely on the fingerprints as representations of the distortions – as the reconstructions improve, the fingerprints better encode the distortions. The FEDR technique was evaluated on synthetic IQ-imbalanced IEEE 802.11a/g data, where FEDR fingerprints were shown to encode actual IQ imbalance parameters, signifying successful isolation of distortion information and validating the FEDR technique. FEDR was further evaluated on a representative real-world WiFi dataset, where extracted fingerprints were coupled with a lightweight two-layer dense network. When compared against two common RFF techniques, the FEDR-based approach achieved state-of-the-art performance with Matthews Correlation Coefficient ranging from 0.984 (5 classes) to 0.851 (100 classes), using nearly 73% fewer training parameters than the next-best technique.