1. Department of Electrical and Information Engineering, Politecnico di Bari 1 , 70125 Bari, Italy
2. Department of Computer Engineering, Modeling, Electronics and Systems, University of Calabria 2 , 87036 Rende, Italy
3. Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina 3 , I-98166 Messina, Italy