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Feature Selection for RF Fingerprinting With Multiple Discriminant Analysis and Using ZigBee Device Emissions

The proliferation of low-cost IEEE 802.15.4 ZigBee wireless devices in critical infrastructure applications presents security challenges. Network security commonly relies on bit-level credentials that are easily replicated and exploited by hackers. Unauthorized access can be mitigated by physical layer (PHY) security measures that exploit device-dependent emission characteristics that are sufficiently unique to discriminate devices. RF distinct native attribute (RF-DNA) fingerprinting is a PHY-based security measure, which computes statistical features extracted from such device emissions. However, the RF-DNA fingerprints can be numerous, correlated, and noisy, therefore, a dimensional reduction analysis (DRA) via feature selection is, therefore, of interest. Device classification with DRA feature subsets is evaluated using a multiple discriminant analysis (MDA) classifier. Determining feature relevance from MDA was generally dismissed in prior RF fingerprinting work and is seldom considered in other applications. Here, the MDA feature relevance is revisited using a proposed eigen-based MDA loadings fusion (MLF) methodology. The MDA classification models are adopted and used to assess device identification (ID) classification and verification performance for both the authorized and unauthorized (rogue) devices using a claimed versus actual biometric methodology. Performance is compared for six DRA methods using: 1) a two-sample Kolmogorov-Smirnov test; 2) one-way analysis of variance F-test statistics; 3) a Wilk's lambda ratio; 4) generalized relevance learning vector quantized-improved relevance; 5) randomly selected; and 6) the proposed MLF method. Quantitative and qualitative dimensionality assessment methods are compared and contrasted to establish upper bounds on the number of retained features. Experimentally collected ZigBee emissions are considered and ZigBee device classification and ID verification performance using DRA subsets are compared with a full-dimensional feature set. Results show that DRA via the proposed MLF method is superior and more robust than competing methods.