  In this paper, we analyze the asymptotic performance of multiple antenna
channels where the transmitter has either perfect or finite bit channel state
information. Using the diversity-multiplexing tradeoff to characterize the
system performance, we demonstrate that channel feedback can fundamentally
change the system behavior. Even one-bit of information can increase the
diversity order of the system compared to the system with no transmitter
information. In addition, as the amount of channel information at the
transmitter increases, the diversity order for each multiplexing gain increases
and goes to infinity for perfect transmitter information. The major reason for
diversity order gain is a "location-dependent" temporal power control, which
adapts the power control strategy based on the average channel conditions of
the channel.
