Antti Tölli Marian Codreanu Markku J. Juntti Linear Multiuser MIMO Transmission with Quality of Service and Per Antenna Power Constraints. 3285-3289 2007 GLOBECOM http://dx.doi.org/10.1109/GLOCOM.2007.623 conf/globecom/2007 db/conf/globecom/globecom2007.html#TolliCJ07