David Gesbert is an Associate Professor with the Department of Mobile Communications, Eurecom Institute, France. Constantinos B. Papadias is a Technical Manager in Lucent Technologies' Bell Labs Wireless and Broadband Access Networks research center. He is currently on leave from Lucent as an Associate Professor at Athens Information Technology (AIT) in Athens, Greece. Alle-Jan van der Veen is a Professor in the Circuits and Systems Group at TU Delft, The Netherlands.