1. Department of Electrical Engineering, Federal University of Campina Grande (UFCG), Campina Grande, Brazil
2. Institute of Telecommunications and Department of Electronics, Telecommunications and Informatics, University of Aveiro, Campus Universitário de Santiago, Aveiro, Portugal
3. Institute for Advanced Studies in Communications (Iecom), Campina Grande, Brazil
4. Department of Electrical Engineering, University of Brasília (UnB), Brasília, Brazil