1. Department of Electrical & Computer Engineering, University of Patras, Rio Campus, Patras, GR-26500, Greece
2. Department of Computer Science and Biomedical Informatics, University of Central Greece, Papasiopoulou 2-4, Lamia, GR-35100, Greece
3. IMEC/Holst Centre, High Tech Campus 31, Eindhoven, 5656AE, The Netherlands