Interference Alignment for the MIMO Interference Channel with Delayed   Local CSIT
  We consider the MIMO (multiple-input multiple-output) Gaussian interference channel with i.i.d. fading across antennas and channel uses and with the delayed local channel state information at the transmitters (CSIT). For the two-user case, achievability results for the degrees of freedom (DoF) region of this channel are provided. We also prove the tightness of our achievable DoF region for some antenna configurations. Interestingly, there are some cases in which the DoF region with delayed local CSIT is identical to the DoF region with perfect CSIT and that is strictly larger than the DoF region with no CSIT. We then consider the $K$-user MISO (multiple-input single-output) IC and show that the degrees of freedom of this channel could be greater than one with delayed local CSIT. 
Akbar Ghasemi, Abolfazl Seyed Motahari, and Amir Keyvan Khandani
cs.IT math.IT