# Composite Fading Models based on Inverse Gamma Shadowing: Theory and Validation

## TL;DR

This paper develops a comprehensive framework for modeling composite wireless fading using inverse gamma shadowing, validated with measurements and providing explicit formulas for key performance metrics.

## Contribution

It introduces a novel approach to composite fading modeling with inverse gamma shadowing, including analytical expressions and validation with real data.

## Key findings

- Inverse gamma effectively models shadow fading in wireless channels.
- Analytical expressions for outage probability are derived for IG-based models.
- Validation shows IG models fit field measurements well.

## Abstract

We introduce a general approach to characterize composite fading models based on inverse gamma (IG) shadowing. We first determine to what extent the IG distribution is an adequate choice for modeling shadow fading, by means of a comprehensive test with field measurements and other distributions conventionally used for this purpose. Then, we prove that the probability density function and cumulative distribution function of any IG-based composite fading model are directly expressed in terms of a Laplace-domain statistic of the underlying fast fading model and, in some relevant cases, as a mixture of wellknown state-of-the-art distributions. Also, exact and asymptotic expressions for the outage probability are provided, which are valid for any choice of baseline fading distribution. Finally, we exemplify our approach by presenting several application examples for IG-based composite fading models, for which their statistical characterization is directly obtained in a simple form.