The Degrees of Freedom Regions of MIMO Broadcast, Interference, and Cognitive Radio Channels with No CSIT

The degrees of freedom (dof) regions are characterized for the multiple-input multipleoutput (MIMO) broadcast channel (BC), the interference channel (IC), and the cognitive radio channel (CRC) when there is perfect and no channel state information at the receivers and the transmitter(s) (CSIR and CSIT), respectively. For the K-user MIMO BC, the exact characterization of the dof region is obtained, which shows that simple time-division-based transmission is dof-region optimal. Using the techniques developed during the analysis of the dof region of the two-user BC, the corresponding problems for the two-user MIMO IC and the two-user MIMO CRC are addressed. For both of these channels, the exact characterization of the dof region is provided, except in a few antenna configurations. In these cases, an outer-bound on the dof region is obtained. All these results are derived for a class of distributions of the fading channel matrices and the additive noises that is more general than those considered in the earlier works such as isotropic fading or Rayleigh fading with white Gaussian noise. Furthermore, using the dof region of the K-user MIMO BC, the dof regions of the K-user MIMO IC and the K-user MIMO CRC are derived in some special cases.