[1] Georgia Inst Technol, Sch Elect & Comp Engn, Telecommun, Atlanta, GA 30332 USA
[2] Tampere Univ Technol, Dept Elect & Commun Engn, FIN-33101 Tampere, Finland
[3] Tampere Univ Technol, Dept Elect & Commun Engn, Nano Commun Ctr, FIN-33101 Tampere, Finland
[4] Tampere Univ Technol, Dept Elect & Commun Engn, FIN-33101 Tampere, Finland
[5] Univ Nebraska, Dept Comp Sci & Engn, Lincoln, NE 68588 USA