The Degrees Of Freedom Of The K-User Mimo Cyclic Z-Interference Channel Under Perfect And Delayed Csit Assumptions

The degrees of freedom (DoF) region for three users and the sum and symmetric DoF for K users are obtained for the multiple-input multiple-output cyclic Z-interference channel with M transmit antennas and N receive antennas at each user pair under the separate assumptions of perfect and delayed channel state information at the transmitters (CSIT). New communication schemes based on interference alignment are developed and are shown to be DoF-optimal for all choices of the number of antennas. The maximum sum-DoF scales linearly with the number of users for both perfect and delayed CSIT.