1. Department of Electrical and Electronic Engineering (DIEE), University of Cagliari, Piazza D’Armi, Cagliari, Italy
2. Department of Mathematics and Computer Science, University of Cagliari, Via Ospedale 72, Cagliari, Italy
3. Department of Informatics Systems and Communication (DISCo), University of Milano—Bicocca, Viale Sarca 336, Milano, Italy