How large portion of K/2 DoF can we achieve at finite SNR in the Gaussian interference channel?

The K/2 degrees of freedom (DoF) of the K-user Gaussian interference channel (GIC) are well known to be achievable for almost all constant real channel coefficients. In this paper, we investigate the sum-rate behavior of the K-user GIC at finite SNR. To this end, we derive closed-form upper bounds on the sum capacity for the symmetric real and semi-symmetric complex cases. We further show how large portion of K/2 DoF is achievable at realistic SNR.