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. ∗ Financial support provided by Nortel and the corresponding matching funds by the Natural Sciences and Engineering Research Council of Canada (NSERC), and Ontario Centers of Excellence (OCE) are gratefully acknowledged. ∗At the final stage of this work, we realized that some parts of the material of this work have been independently reported in [11]. ar X iv :1 10 2. 56 73 v1 [ cs .I T ] 2 8 Fe b 20 11