Gaussian Interference Channel with Intermittent Feedback

TL;DR

This paper studies how intermittent feedback can be used to improve capacity in two-user Gaussian interference channels, providing approximate capacity regions and novel coding schemes that leverage unreliable feedback.

Contribution

It offers the first approximate capacity characterization for Gaussian IC with intermittent feedback and introduces a new scheme using quantize-map-and-forward without structured codes.

Findings

Passive feedback can significantly increase capacity.

High probability feedback achieves near-perfect sum-capacity.

New outer bounds improve understanding of feedback's role.

Abstract

We investigate how to exploit intermittent feedback for interference management by studying the two-user Gaussian interference channel (IC). We approximately characterize (within a universal constant) the capacity region for the Gaussian IC with intermittent feedback. We exactly characterize the the capacity region of the linear deterministic version of the problem, which gives us insight into the Gaussian problem. We find that the characterization only depends on the forward channel parameters and the marginal probability distribution of each feedback link. The result shows that passive and unreliable feedback can be harnessed to provide multiplicative capacity gain in Gaussian interference channels. We find that when the feedback links are active with sufficiently large probabilities, the perfect feedback sum-capacity is achieved to within a constant gap. In contrast to other schemes developed for interference channel with feedback, our achievable scheme makes use of quantize-map-and-forward to relay the information obtained through feedback, performs forward decoding, and does not use structured codes. We also develop new outer bounds enabling us to obtain the (approximate) characterization of the capacity region.