1. Department of Electrical, Computer, and System Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, USA
2. RPI/IBM Center for Broadband Data Transfer, CII 9015, Rensselaer Polytechnic Institute, Troy, New York 12180, USA
3. Institute of Radio Engineering and Electronics (Saratov Branch), ul. Zelyonaya 38, Saratov 410019, Russia