Approximate Capacity Region for the Symmetric Gaussian Interference Channel with Noisy Feedback

Sy Quoc Le, Ravi Tandon, Mehul Motani, H. Vincent Poor

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Recent results have shown that feedback can significantly increase the capacity of interference networks. This paper considers the impact of noise on such gains due to feedback. In particular, this paper considers the two-user linear deterministic interference channel with noisy feedback, as a stepping stone to characterize the approximate capacity region for the two-user Gaussian interference channel with noisy feedback. First, the capacity region for the symmetric linear deterministic interference channel with noisy feedback is obtained. It is shown that noisy feedback enlarges the capacity region if and only if the number of feedback bits l is greater than a certain threshold l. It is found that, excluding the regime (1/2) ≤ α ≤ 2, where α is the normalized interference level, in which even full feedback does not increase symmetric capacity, this threshold l is equal to the per-user symmetric capacity without feedback. One of the key ideas is a novel converse outer bounding technique for the weighted sum rates 2R1 + R2 and R1 + 2R2. These results and the techniques developed for the linear deterministic model are then applied to characterize inner bounds and outer bounds for the symmetric Gaussian interference channel with noisy feedback. The outer bounds are shown to be at most 4.7 b/s/Hz away from the achievable rate region. As a corollary, the generalized-degrees-of-freedom region, which approximates the capacity region of the symmetric Gaussian interference channel at high SNR, is found.

Original languageEnglish (US)
Article number7109914
Pages (from-to)3737-3762
Number of pages26
JournalIEEE Transactions on Information Theory
Volume61
Issue number7
DOIs
StatePublished - Jul 1 2015

All Science Journal Classification (ASJC) codes

  • Information Systems
  • Computer Science Applications
  • Library and Information Sciences

Keywords

  • Channel output feedback
  • capacity
  • degrees of freedom
  • interference channel
  • noisy feedback

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