1. PhD Programme in Biomedical Engineering, ETSI Telecomunicación, Universidad Politécnica de Madrid, 28040 Madrid, Spain
2. Research Group on Biometrics, Biosignals, Security and Smart Mobility, UPM’s R&D+i Center for Energy Efficiency, Virtual Reality, Optical Engineering and Biometrics (CeDInt-UPM), Campus Montegancedo of International Excelence, Universidad Politécnica de Madrid, 28223 Pozuelo de Alarcón, Spain
3. Department of Applied Mathematics to ICT, ETSI Telecomunicación, Universidad Politécnica de Madrid, 28040 Madrid, Spain