Computers and Electrical Engineering 76 (2019) 364–378 Contents lists available at ScienceDirect Computers and Electrical Engineering journal homepage: www.elsevier.com/locate/compeleceng Radiometric identification using variational mode decomposition  Gianmarco Baldini a,∗ , Gary Steri a , Raimondo Giuliani a , Franc Dimc b a European Commission, Joint Research Centre, Ispra, 21027, Italy b University of Ljubljana, Faculty of Maritime Studies and Transport, Portorož, 6320, Slovenia a r t i c l e i n f o Article history: Received 14 August 2018 Revised 12 April 2019 Accepted 15 April 2019 Keywords: Signal processing Authentication Security Wireless communications Radiometric identification Variational mode decomposition a b s t r a c t Radiometric Identification (RAI) is the identification of wireless devices through their Ra- dio Frequency (RF) emissions. In recent years, the research community has investigated it applying different methods and sets of statistical features extracted from the digitized RF emissions. In this paper, the authors investigate the application of Variational Mode De- composition (VMD), recently introduced as an improvement to Empirical Mode Decompo- sition (EMD). VMD is applied to two sets of RF emissions from: wireless devices supporting Dedicated Short Range Communications (DSRC) at 5.9 GHz and Internet of Things wireless devices transmitting in the Industrial, Scientific and Medical (ISM) band at 2.4 GHz. Various machine learning algorithms have been used for classification and results are compared. Performances of VMD are evaluated against other approaches used in literature in Line of Sight (LOS) conditions, with Additive White Gaussian Noise (AWGN) and fading effects. Results show that VMD significantly outperforms other approaches. © 2019 Published by Elsevier Ltd. 1. Introduction Radiometric Identification (RAI) is a technique to identify and authenticate wireless devices through their Radio Fre- quency (RF) emissions. The effectiveness of such techniques have been demonstrated in literature in various settings and propagation conditions. RAI exploits the presence of small differences in the material and the composition of the front-ends used for wireless transmission. These differences are usually not significant to hamper the correct functioning of wireless services but they are relevant enough for the unique identification of the model or the wireless device itself [1]. A synonym of RAI is also Radio Frequency - DNA (RF-DNA) because such small differences resemble the DNA of the human beings or RF fingerprinting like the fingerprints of the human skin of the fingers [2]. RAI is suitable for various applications [1], which are briefly described here. For security applications, multi-factor au- thentication using RF fingerprints has been proposed by many research papers [1–3]. The idea is that radiometric identi- fication can be used as a form of authentication and complement conventional authentication means using cryptography. Because, radiometric identification is based on intrinsic physical features of the electronic device, these features cannot be stolen and they are quite difficult to reproduce. In this context, an authentication system can first collect the RF fingerprints (e.g., before market deployment or before they are put in service) and then compares them with the RF signal from the wireless device to authenticate. In the fight against the distribution of counterfeit electronic products, the authentication  This paper is for regular issues of CAEE. Reviews processed and recommended for publication to the Editor-in-Chief by Area Editor Dr. E. Cabal-Yepez. ∗ Corresponding author. E-mail address: gianmarco.baldini@ec.europa.eu (G. Baldini). https://doi.org/10.1016/j.compeleceng.2019.04.014 0045-7906/© 2019 Published by Elsevier Ltd.