1. Nokia Bell Labs, Murray Hill, NJ, USA
2. Nokia Bell Labs Munich, Munich, Germany
3. Nokia Technology Center, Ulm, Germany
4. Nokia Bell Labs Stuttgart, Stuttgart, Germany
5. Department of Electronic Systems, Aalborg University, Aalborg, Denmark
6. Department of Electronics Engineering, Universidad Tecnica Federico Santa Maria, Valparaíso, Chile
7. Escuela de Ingeniería Eléctrica, Pontificia Universidad Catolica de Valparaíso, Valparaíso, Chile