K-user Interference Channels: General Outer Bound and Sum-capacity for Certain Gaussian Channels

TL;DR

This paper presents a universal outer bound on the capacity region for any memoryless interference channel with multiple users, extending previous two-user results and identifying channels where this bound achieves sum-capacity.

Contribution

It introduces the first known outer bound applicable to any memoryless interference channel and characterizes channels where this bound is tight for sum-capacity.

Findings

Derived a general outer bound for K-user interference channels

Identified classes of Gaussian channels where the bound is tight

Extended techniques from two-user to multi-user interference channels

Abstract

This paper derives an outer bound on the capacity region of a general memoryless interference channel with an arbitrary number of users. The derivation follows from a generalization of the techniques developed by Kramer and by Etkin et al for the Gaussian two-user channel. The derived bound is the first known outer bound valid for any memoryless channel. In Gaussian noise, classes of channels for which the proposed bound gives the sum-rate capacity are identified, including degraded channels and a class of Z-channels.