1. Department of Communications, University of Campinas (UNICAMP), Campinas, Brazil
2. São Paulo State University (UNESP), Campus of São João da Boa Vista, São João da Boa Vista, Brazil
3. Department of Electrical Engineering, Federal University of Triângulo Mineiro (UFTM), Uberaba, Brazil
4. Department of Mathematics, University of Campinas (UNICAMP), Campinas, Brazil