A New Outer Bound and the Noisy-Interference Sum-Rate Capacity for Gaussian Interference Channels

TL;DR

This paper introduces a new outer bound for Gaussian interference channels, establishing the sum-rate capacity under noisy interference conditions and identifying optimal decoding strategies at finite SNR.

Contribution

It develops an improved outer bound that combines genie-aided methods and determines sum-rate capacity for noisy interference scenarios.

Findings

Single-user detection is sum-rate optimal under certain conditions.

First finite SNR capacity result for weak to moderate interference.

Outer bounds identify capacity region corner points in mixed interference cases.

Abstract

A new outer bound on the capacity region of Gaussian interference channels is developed. The bound combines and improves existing genie-aided methods and is shown to give the sum-rate capacity for noisy interference as defined in this paper. Specifically, it is shown that if the channel coefficients and power constraints satisfy a simple condition then single-user detection at each receiver is sum-rate optimal, i.e., treating the interference as noise incurs no loss in performance. This is the first concrete (finite signal-to-noise ratio) capacity result for the Gaussian interference channel with weak to moderate interference. Furthermore, for certain mixed (weak and strong) interference scenarios, the new outer bounds give a corner point of the capacity region.