Diversity-multiplexing tradeoff for MIMO wire-tap channels with CSIT

In this paper fading multiple-antenna (MIMO) wiretap channels are investigated under short term power constraints. The secret diversity-multiplexing tradeoff (DMT) is calculated analytically, when the destination and the eavesdropper have receiver side channel state information (CSI) and the source has transmitter side CSI (CSIT). It is shown that the eavesdropper steals transmitter antennas and the secret DMT depends on the effective number of antennas left. This is in contrast to the no CSIT case, where the eavesdropper effectively steals both transmit and receive antennas. A zero-forcing type scheme is shown to achieve the secret DMT when CSIT is available.