Inverse Moment Matching Based Analysis of Cooperative HARQ-IR over Time-Correlated Nakagami Fading Channels

TL;DR

This paper presents a new analytical method for evaluating the outage probability of cooperative HARQ-IR over time-correlated Nakagami fading channels, revealing its diversity benefits and optimal rate strategies.

Contribution

It introduces an inverse moment matching approach for outage probability approximation and analyzes the diversity order independence from time correlation.

Findings

Diversity order remains unaffected by time correlation coefficient $ ho$ for $ ho<1$.

Cooperative HARQ-IR achieves full diversity in spatial and time domains.

High fading order and low channel correlation improve scheme performance.

Abstract

This paper analyzes the performance of cooperative hybrid automatic repeat request with incremental redundancy (HARQ-IR) and proposes a new approach of outage probability approximation for performance analysis. A general time-correlated Nakagami fading channel covering fast fading and Rayleigh fading as special cases is considered here. An efficient inverse moment matching method is proposed to approximate the outage probability in closed-form. The effect of approximation degree is theoretically analyzed to ease its selection. Moreover, diversity order of cooperative HARQ-IR is analyzed. It is proved that diversity order is irrelevant to the time correlation coefficient $\rho$ as long as $\rho<1$ and full diversity from both spatial and time domains can be achieved by cooperative HARQ-IR under time-correlated fading channels. The accuracy of the analytical results is verified by computer simulations and the results reveal that cooperative HARQ-IR scheme can benefit from high fading order and low channel time correlation. Optimal rate selection to maximize the long term average throughput given a maximum allowable outage probability is finally discussed as one application of the analytical results.