1. Department of Electrical Engineering, University of Brasilia, Brasília, Brazil
2. Department of Telecommunications, Aeronautics Institute of Technology (ITA), São José dos Campos, Brazil
3. Communications Research Laboratory, Technische Universität Ilmenau, Ilmenau, Germany
4. Faculty of Electrical Engineering and Information Technology, Technische Hochschule Ingolstadt, Ingolstadt, Germany