1. Instituto de Telecomunicações and Departamento de Eletrónica, Telecomunicações e Informática, Universidade de Aveiro, Campus Universitário de Santiago, Aveiro, Portugal
2. Department of Electrical Engineering, Federal University of Campina Grande, Campina Grande, Brazil
3. National Institute of Telecommunications (Inatel), Santa Rita do Sapucaí, Brazil
4. School of Electrical and Information Engineering, The University of Sydney, Sydney, NSW, Australia