On the Sum Capacity of K-user Cascade Gaussian Z-Interference Channel

TL;DR

This paper analyzes the sum capacity of a specific K-user cascade Gaussian Z-interference channel, showing that simple Han-Kobayashi schemes with Gaussian inputs can nearly achieve the maximum sum rate under certain conditions.

Contribution

It characterizes the sum capacity for the K-user cascade Gaussian Z-interference channel using simple Han-Kobayashi schemes and identifies conditions where the sum rate is optimal or near-optimal.

Findings

Maximum sum rate achieved by common or private signals.

For K=3, sum rate within 0.5 bits of capacity under certain conditions.

Conditions under which the sum rate equals the sum capacity.

Abstract

A $K$-user cascade Gaussian Z-interference channel is a subclass of the general $K$-user Gaussian interference channel, where each user, except the first one, experiences interference only from the previous user. Under simple Han-Kobayashi schemes assuming Gaussian inputs and no time sharing, it is shown that the maximum sum rate is achieved by each user transmitting either common or private signals. For K=3, channel conditions under which the achieved sum rate is either equal to or within 0.5 bits to the sum capacity are identified.