Peilu Ding David James Love Michael D. Zoltowski Multiple Antenna Broadcast Channels With Shape Feedback and Limited Feedback. 3417-3428 2007 55 IEEE Transactions on Signal Processing 7-1 http://doi.ieeecomputersociety.org/10.1109/TSP.2007.893908 db/journals/tsp/tsp55.html#DingLZ07