Interference Alignment and Degrees of Freedom of the -User Interference Channel

  • Authors:
  • V. R. Cadambe;S. A. Jafar

  • Affiliations:
  • Dept. of Electr. Eng. & Comput. Sci., California Irvine Univ., Irvine, CA;-

  • Venue:
  • IEEE Transactions on Information Theory
  • Year:
  • 2008

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Abstract

For the fully connected K user wireless interference channel where the channel coefficients are time-varying and are drawn from a continuous distribution, the sum capacity is characterized as C(SNR)=K/2log(SNR)+o(log(SNR)) . Thus, the K user time-varying interference channel almost surely has K/2 degrees of freedom. Achievability is based on the idea of interference alignment. Examples are also provided of fully connected K user interference channels with constant (not time-varying) coefficients where the capacity is exactly achieved by interference alignment at all SNR values.