Degrees of Freedom of the $K$ User $M \times N$ MIMO Interference Channel

Understand

We provide innerbound and outerbound for the total number of degrees of freedom of the $K$ user multiple input multiple output (MIMO) Gaussian interference channel with $M$ antennas at each transmitter and $N$ antennas at each receiver if the channel coefficients are time-varying and drawn from a continuous distribution.

• The bounds are tight when the ratio $\frac{\max(M,N)}{\min(M,N)}=R$ is equal to an integer.
• For this case, we show that the total number of degrees of freedom is equal to $\min(M,N)K$ if $K \leq R$ and $\min(M,N)\frac{R}{R+1}K$ if $K > R$.
• Achievability is based on interference alignment.