[IEEE 2015 International Conference on Humanoid, Nanotechnology, Information Technology,Communication and Control, Environment and Management (HNICEM) - Cebu City, Philippines (2015.12.9-2015.12.12)] 2015 International Conference on Humanoid, Nanotechnology, Information Technology,Communication and Control, Environment and Management (HNICEM) - Accuracy improvement of ESPRIT-extracted directionof- arrival estimates using least mean-squares filter for passive RFID inventory application