RRT: Rural Ray Tracing

Introduction

The wave propagation in rural and suburban scenarios is very often characterized by multi-path propagation due to interactions (reflections, diffractions, scattering,...) at various obstacles (hills, buildings, towers, etc.). Simple empirical propagation models for these scenarios do either ignore the topography between transmitter and receiver (Okumura-Hata, Empirical Two Ray Model) or they consider only the shadowing due to obstacles in the vertical plane (Deterministic Two Ray Model). More sophisticated approaches include multiple diffractions in the vertical plane (Knife Edge Diffraction Models) or they compute the waveguiding around obstacles in 3D (Dominant Path Model).

All these prediction models listed above and included in the PRO-R module of WinProp are focusing "only" on a single propagation path.
But in reality there are very often more propagation paths between transmitter and receiver. And only the superposition of all these paths leads to an accurate prediction. Therefore a (deterministic) multi path propagation model considering phenomena like multiple reflections and wave guiding effects in canyons is required to obtain accurate predictions of the signal level and the spatial channel impulse response.

WinProp provides such a model based on the fast deterministic 3D ray tracing models of AWE Communications already available for indoor and urban scenarios for many years.

Preparation of Topography

The approach of the RRT (Rural Ray Tracing) requires in a first step the conversion of the topography data (in pixel format) to a 3D vector data format. This step has to be made once for each scenario (database) and after the conversion the topography in vector format can be used for predictions with the ray optical prediction models.

Consideration of Land Usage (Clutter)

The additional consideration of land usage (clutter) maps is of course also possible. Similar to the topographical data, the clutter maps are also converted from raster data to 3D vector data taking account the clutter heights and the electrical properties of the materials defined for each clutter class individually.
This approach allows a real 3D representation of the land usage maps.

Additional obstacles

Beyond topography and land usage (clutter) also arbitrary 3D vector objects can be defined in the scenario to model buildings, towers, etc.

These obstacles can either be converted from CAD data (various CAD data formats are supported) or they can be drawn in 3D with WinProp's CAD tool WallMan into a 3D vector database.

Of course the material properties of each 3D obstacle can be defined individually.

Additional vector objects in topo and land usage databases
(land usage incl. individual heights for each clutter class)

Prediction with Ray Tracing Model

Based on the vector data of topography, clutter and 3D obstacles, the predictions with the well known Ray Tracing models can be computed. These models combine short prediction times with high accuracy.

Consideration of Time Variance

On top of oridinary predictions the consideration of time variance allows propagation computations with moving objects, e.g. cars or trains.
This is often required for the development of receivers for various applications such as Car-2-X communication or in-car LTE/DAB/DVB-T reception.

Trajectories can be imported from several file formats in order to define the movements of time variant objects.

Brochure with rural propagation models

See a comparison between different rural prediction models.

Read more about the Indoor Ray Tracing Models