Riichi Kudo Yasushi Takatori Atsushi Ohta Kentaro Nishimori Shuji Kubota New Simple Capacity Estimation Method for Multiuser Block Diagonalization Transmission. 1836-1840 2007 conf/vtc/2007s VTC Spring http://dx.doi.org/10.1109/VETECS.2007.381 db/conf/vtc/vtc2007s.html#KudoTONK07