1. Department of Electrical and Information Engineering, Politecnico di Bari, Bari, Italy
2. Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, Messina, Italy
3. Department of Engineering, University of Messina, Messina, Italy
4. Technical University of Kaiserslautern and Landesforschungszentrum OPTIMAS, Kaiserslautern, Germany