On the Diversity Gain Region of the Z-interference Channels

TL;DR

This paper characterizes the diversity gain region of the Rayleigh fading Z-Interference channel, showing the optimality of a simplified Han-Kobayashi scheme and the ineffectiveness of generalized time sharing for improving DGR.

Contribution

It provides a closed-form characterization of the DGR for the ZIC and identifies the optimality of a specific HK scheme with only a common message.

Findings

HK scheme with only a common message achieves the best DGR for certain multiplexing gains

Generalized time sharing does not improve the achievable DGR

Closed-form expression for the DGR of the ZIC

Abstract

In this work, we analyze the diversity gain region (DGR) of the single-antenna Rayleigh fading Z-Interference channel (ZIC). More specifically, we characterize the achievable DGR of the fixed-power split Han-Kobayashi (HK) approach under these assumptions. Our characterization comes in a closed form and demonstrates that the HK scheme with only a common message is a singular case, which achieves the best DGR among all HK schemes for certain multiplexing gains. Finally, we show that generalized time sharing, with variable rate and power assignments for the common and private messages, does not improve the achievable DGR.