1. Department of Communication Sciences, Rey Juan Carlos University, Madrid, Spain.
2. Department of Telematics, University of Cauca, Popayán, Colombia.
3. Department of Telematic Systems Engineering, Polytechnic University of Madrid, Madrid, Spain.
4. Department of Social Medicine and Family Health, University of Cauca, Popayán, Columbia.
5. Department of Signal Theory and Communications, Carlos III University, Madrid, Spain.