Table 1.

Summary of radar based Unmanned Aerial Vehicle (UAV) detection and classification methods in recent literature

Task	Signal Processing	Classification	Reference
Feature extraction	MDS${}^1$ with spectrogram, handcrafted features	-	[19]
Feature extraction	MDS with spectrogram and cepstrogram, handcrafted features	-	[20]
UAV classification	MDS with spectrogram, Eigenpairs extracted from MDS	linear and non linear SVM${}^2$, NBC${}^3$	[16]
UAV classification, feature extraction	MDS with spectrogram, cepstrogram and CVD${}^4$, SVD${}^5$ on MDS	SVM	[21,22]
UAV classification, feature extraction	MDS with 2D regularized complex-log-Fourier transform	Subspace reliability analysis	[23]
UAV classification, feature extraction	MDS with EMD${}^6$, features from EMD	SVM	[24]
UAV classification, feature extraction	MDS with EMD, entropy from EMD features	SVM	[25]
UAV classification, localization	MDS with EMD, PCA${}^7$ on MDS	Nearest Neighbor, NBC, random forest, SVM	[26]
UAV classification	MDS with spectrogram, handcrafted features	NBC, DAC${}^8$	[27]
UAV detection, tracking	MDS with spectrogram, CFAR${}^9$ for detection, Kalman for tracking	-	[28]
UAV classification, feature extraction	MDS with spectrogram, PCA on MDS	SVM	[29]
UAV trajectory classification	Features from moving direction, velocity, and position of the target	Probabilistic motion estimation model	[30]
UAV trajectory and type classification, feature extraction	Features from motion, velocity, signature	SVM	[31]
UAV classification, feature extraction	Radar polarimetric features	Nearest Neighbor	[32]
UAV classification	MDS with spectrogram and CVD	CNN${}^{10}$	[33]
UAV classification	SCF${}^{11}$ reference banks	DBN${}^{12}$	[34]
Target detection	Doppler processing	CNN	[35]
UAV classification	Direct learning on Range Profile matrix	CNN	[36]
UAV classification	Direct learning on IQ${}^{13}$ signal	MLP${}^{14}$	[37]
UAV classification	Point cloud from radar signal	MLP	[38]
UAV trajectory classification, feature extraction	Features from motion, velocity, RCS${}^{15}$	MLP	[39]

MDS${}^1$: Micro Doppler Signature, SVM${}^2$: Support Vector Machine, NBC${}^3$: Naive Bayes Classifier, CVD${}^4$: Cadence Velocity Diagram, SVD${}^5$: Singular Value Decomposition, EMD${}^6$: Empirical Mode Decomposition, PCA${}^7$: Principal Component Analysis, DAC${}^8$: Discriminant Analysis Classifier, CFAR${}^9$: Constant False Alarm Rate, CNN${}^{10}$: Convolutional Neural Network, SCF${}^{11}$: Spectral Correlation Function, DBN${}^{12}$: Deep Belief Network, IQ${}^{13}$: In-phase and Quadrature, MLP${}^{14}$: Multi Layer Perceptron, RCS${}^{15}$: Radar Cross Section.