Modeling of Reverberant Radio Channels Using Propagation Graphs

TL;DR

This paper introduces a propagation graph model for reverberant radio channels that captures the exponential power decay and avalanche effect observed in in-room measurements, providing a closed-form transfer matrix for simulations.

Contribution

It presents a novel propagation graph framework with a closed-form transfer matrix to model complex reverberant radio channels.

Findings

The model reproduces exponential power decay.

It captures the avalanche effect in channel responses.

The transfer matrix simplifies numerical simulations.

Abstract

In measurements of in-room radio channel responses an avalanche effect can be observed: earliest signal components, which appear well separated in delay, are followed by an avalanche of components arriving with increasing rate of occurrence, gradually merging into a diffuse tail with exponentially decaying power. We model the channel as a propagation graph in which vertices represent transmitters, receivers, and scatterers, while edges represent propagation conditions between vertices. The recursive structure of the graph accounts for the exponential power decay and the avalanche effect. We derive a closed form expression for the graph's transfer matrix. This expression is valid for any number of interactions and is straightforward to use in numerical simulations. We discuss an example where time dispersion occurs only due to propagation in between vertices. Numerical experiments reveal that the graph's recursive structure yields both an exponential power decay and an avalanche effect.