Degrees of freedom for the MIMO interference channel
In this correspondence, we show that the exact number of spatial degrees of freedom (DOF) for a two user nondegenerate (full rank channel matrices) multiple-input-multiple-output (MIMO) Gaussian interference channel with M-1, M-2 antennas at transmitters 1, 2 and N-1, N-2 antennas at the corresponding receivers, and perfect channel knowledge at all transmitters and receivers, is min{M-1 + M-2, N-1 + N-2, max(M-1, M-2), max(M-2, N-1)}. A constructive achievability proof shows that zero forcing is sufficient to achieve all the available DOF on the two user MIMO interference channel. We also show through an example of a share-and-transmit scheme how the gains of transmitter cooperation may be entirely offset by the cost of enabling that cooperation so that the available DOF are not increased.
interference degrees of freedom (dof) multiple-input-multiple-output (mimo) zero forcing broadeast multiple access