Improper Signaling Versus Time-Sharing in the Two-User Gaussian Interference Channel with TIN

Christoph Hellings, Wolfgang Utschick

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

So-called improper complex signals have been shown to be beneficial in the single-antenna two-user Gaussian interference channel under the assumptions that all input signals are Gaussian and that we treat interference as noise (TIN). This result has been obtained under a restriction to pure strategies without time-sharing, and it was extended to the case where the rates, but not the transmit powers, may be averaged over several transmit strategies. In this paper, we drop such restrictions and discuss the most general case of coded time-sharing, where both the rates and the powers may be averaged. Since coded time-sharing can in general not be expressed by means of a convex hull of the rate region, we have to account for the possibility of time-sharing already during the optimization of the transmit strategy. By means of a novel channel enhancement argument, we prove a surprising result: proper signals are optimal if coded time-sharing is allowed. In addition to establishing this result, we present an algorithm to compute the corresponding achievable rate region.

Original languageEnglish
Article number8959147
Pages (from-to)2988-2999
Number of pages12
JournalIEEE Transactions on Information Theory
Volume66
Issue number5
DOIs
StatePublished - May 2020

Keywords

  • Improper signaling
  • interference channel
  • rate region
  • time-sharing
  • treat interference as noise

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