Manish Airy Sandeep Bhadra Robert W. Heath Jr. Sanjay Shakkottai Transmit Precoding for the Multiple Antenna Broadcast Channel. 1396-1400 2006 conf/vtc/2006s VTC Spring http://dx.doi.org/10.1109/VETECS.2006.1683064 db/conf/vtc/vtc2006s.html#AiryBHS06