Interference Channels with Rate-Limited Feedback

TL;DR

This paper investigates the two-user interference channel with rate-limited feedback, proposing new schemes and bounds across deterministic and Gaussian models, and demonstrating near-optimality in the Gaussian case.

Contribution

It introduces novel achievable schemes and outer-bounds for rate-limited feedback interference channels, establishing optimality in certain deterministic models and bounded gaps in Gaussian models.

Findings

Achievable schemes using Han-Kobayashi, quantize-and-binning, and decode-and-forward techniques.

New outer-bounds for all three models studied.

Constant-gap optimality for symmetric Gaussian channels.

Abstract

We consider the two-user interference channel with rate-limited feedback. Related prior works focus on the case where feedback links have infinite capacity, while no research has been done for the rate-limited feedback problem. Several new challenges arise due to the capacity limitations of the feedback links, both in deriving inner-bounds and outer-bounds. We study this problem under three different interference models: the El Gamal-Costa deterministic model, the linear deterministic model, and the Gaussian model. For the first two models, we develop an achievable scheme that employs three techniques: Han-Kobayashi message splitting, quantize-and-binning, and decode-and-forward. We also derive new outer-bounds for all three models and we show the optimality of our scheme under the linear deterministic model. In the Gaussian case, we propose a transmission strategy that incorporates lattice codes, inspired by the ideas developed in the first two models. For symmetric channel gains, we prove that the gap between the achievable sum-rate of the proposed scheme and our new outer-bounds is bounded by a constant number of bits, independent of the channel gains.