Completely stale transmitter channel state information is still very useful

FREE-DOWNLOAD MA Maddah-Ali… – Communication, Control, and …, 2010
Abstract—Transmitter channel state information (CSIT) is cru- cial for the multiplexing gains offered
by advanced interference management techniques such as multiuser MIMO and interfer- ence
alignment. Such CSIT is usually obtained by feedback from the receivers, but the