Hongmei Wang Xibin Xu Ming Zhao 0001 Yan Yao Efficient Transmission Strategies Against Channel Time Variations in Multiuser MIMO Downlink Systems. 3514-3518 2007 GLOBECOM http://dx.doi.org/10.1109/GLOCOM.2007.667 conf/globecom/2007 db/conf/globecom/globecom2007.html#WangX0Y07