Generalized degrees of freedom of the symmetric Gaussian K user interference channel

  • Authors:
  • Syed A. Jafar;Sriram Vishwanath

  • Affiliations:
  • Electrical Engineering and Computer Science University of California, Irvine, CA;Department of Electrical Engineering, University of Texas, Austin, TX

  • Venue:
  • IEEE Transactions on Information Theory
  • Year:
  • 2010

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Abstract

We characterize the generalized degrees of freedom of the K user symmetric Gaussian interference channel where all desired links have the same signal-to-noise ratio (SNR) and all undesired links carrying interference have the same interference-to-noise ratio, INR = SNRα. We find that the number of generalized degrees of freedom per user, d(α), does not depend on the number of users, so that the characterization is identical to the 2 user interference channel with the exception of a singularity at α = 1 where d(1) = 1/K. The achievable schemes use multilevel coding with a nested lattice structure that opens the possibility that the sum of interfering signals can be decoded at a receiver even though the messages carried by the interfering signals are not decodable.