3D indoor positioning CNN Energy industries & utilities History of engineering & technology IREAD 4.0 Industry 4.0 RFID classification method RSSI RSSI-based positioning Technology: general issues Wi-Fi positioning acoustic diffraction acoustic localization acoustic signal aberration ambiguity resolution angle of arrival book tracking carrier phase clustering cross-correlation aberration cyber-physical system distance metric extended Kalman filter ferroelectric films fingerprint positioning fingerprint-based indoor positioning frequency dependent attenuation indoor localization indoor positioning system information service