1. Department of Electrical, Electronic and Information Engineering Guglielmo Marconi “Guglielmo Marconi”, University of Bologna, Cesena, Italy
2. Department of Electrical, Electronic and Information Engineering Guglielmo Marconi “Guglielmo Marconi”, University of Bologna, Bologna, Italy
3. National Research Council of Italy, IEIIT-CNR, Rome, Italy
4. CEA, LETI, MINATEC Campus, Grenoble, France