# Summary of Wave Propagation Models for Indoor Scenarios

A summary of the indoor wave propagation models in tabular format.

Model | One Slope Model (Modified Free Space Model) |
Motley-Keenan Model | Multi-Wall (COST 231) Model |
---|---|---|---|

Type |
Empirical | Empirical | Empirical |

Valid for |
Rough estimation only. | Scenarios where the direct ray is dominating. | Scenarios where the direct ray is dominating. |

Accuracy |
Low | Moderate | Moderate |

Computation Time |
Very short | Very short | Very short |

Preprocessing of
Database |
Not required | Not required | Not required |

Problem Type &
Size |
Very rough estimation of radio coverage for arbitrary scenarios. | Rough estimation of radio coverage for arbitrary scenarios. | Estimation of radio coverage for arbitrary scenarios. |

Considers |
The model considers the path loss based on the direct ray between the transmitter and receiver. | The model considers the path loss based on the direct ray between the transmitter and receiver. It takes into account the exact locations of the building's walls, floors and ceilings. | The model considers the path loss based on the direct ray between the transmitter and receiver. It takes into account the exact locations of the building's walls, floors and ceilings and their individual material properties. |

Limitations |
Model does not consider the attenuations of walls. | Model does not consider the material properties of the individual walls (uniform transmission/penetration loss is used for all walls). | Model does not consider reflection and diffraction. |

Model | 3D Dominant Path Model | 3D Shooting and Bouncing Rays | 3D Intelligent Ray Tracing | 3D Standard Ray Tracing |
---|---|---|---|---|

Type |
Semi-deterministic | Deterministic | Deterministic | Deterministic |

Valid for |
All scenarios, in case multipath effects are not required / dominating. | All scenarios, the wavelength should be smaller than the extension of the considered obstacles, for example, the walls of a building. | All scenarios, the wavelength should be smaller than the extension of the considered obstacles, for example, the walls of a building. | All scenarios, the wavelength should be smaller than the extension of the considered obstacles, for example, the walls of a building. |

Accuracy |
High | High | High | Very high |

Computation Time |
Short | Medium, could be long for considering (multiple) diffractions | Typically minutes after preprocessing for IRT. | Medium to long, depending on the number of objects (walls/polygons) and the number of interactions (reflections, but especially diffractions) to be considered. |

Preprocessing of Database |
Not required | Not required | Yes | Not required |

Problem Type & Size |
Radio coverage for arbitrary scenarios, e.g. large multi-floor buildings. | Radio channel incl. multipath and radio coverage simulation for arbitrary scenarios, well suited for tunnels as reflections are computed very efficiently. | Radio channel incl. multipath and radio coverage simulation for arbitrary scenarios, which can still be handled by the preprocessing. | Radio channel incl. multipath and radio coverage simulation for arbitrary scenarios, which are still feasible in size. |

Considers |
The model considers the dominant path between the transmitter and the receiver. It takes into account the individual interaction losses when the propagation path changes its propagation direction, the individual transmission losses for the walls and waveguiding effects. | The model performs a rigorous 3D ray-launching prediction which results in a high accuracy. | The model uses the visibility relations between walls and edges (computed during preprocessing) to accelerate the ray path finding. | The model performs a rigorous 3D ray-tracing prediction. |

Limitations |
Model does not compute the multipath situation but only the single dominant propagation path. | Model can be computationally expensive, especially for considering (multiple) diffractions. | Model requires a single preprocessing of the given scenario. | Computation time could be long depending on the number of objects (walls/polygons) and the number of interactions (reflections, but especially diffractions) to be considered |