1. Communication Engineering Department; Federal University of Rio Grande do Norte (UFRN), Av. Senador Salgado Filho, 3000; Natal RN, CEP: 59072-970 Brazil
2. Federal Institute of Education; Science and Technology of Paraíba (IFPB), Campus, João Pessoa, Av. 1 de maio, 720, Jaguaribe; João Pessoa PB, CEP: 58015430 Brazil