Propagation models allow you to predict the propagation and attenuation of radio
signals as the signals travel through the environment. You can simulate different
models by using the propagationModel
function. Additionally, you can
determine the range and path loss of radio signals in these simulated models by
using the range
and pathloss
functions.
The following sections describe various propagation and ray tracing models. The
tables in each section list the models that are supported by the
propagationModel
function and compare, for each model, the
supported frequency ranges, model combinations, and limitations.
Atmospheric propagation models predict path loss between sites as a function of distance. These models assume lineofsight (LOS) conditions and disregard the curvature of the Earth, terrain, and other obstacles.
Model  Description  Frequency  Combinations  Limitations 

freespace  Ideal propagation model with clear line of sight between transmitter and receiver  No enforced range  Can be combined with rain, fog, and gas  Assumes line of sight 
rain  Propagation of a radio wave signal and its path loss in rain. For more information, see [3].  1 to 1000 GHz  Can be combined with any other propagation model  Assumes line of sight 
gas  Propagation of radio wave signal and its path loss due to oxygen and water vapor. For more information, see [5].  1 to 1000 GHz  Can be combined with any other propagation model  Assumes line of sight 
fog  Propagation of the radio wave signal and its path loss in cloud and fog. For more information, see [2].  10 to 1000 GHz  Can be combined with any other propagation model  Assumes line of sight 
Like atmospheric propagation models, empirical models predict path loss as a function of distance. Unlike atmospheric models, the closein empirical model supports nonlineofsight (NLOS) conditions.
Model  Description  Frequency  Combinations  Limitations 

closein  Propagation of signals in urban macro cell scenarios. For more information, see [1].  No enforced range  Can be combined with rain, fog, and gas  — 
Terrain propagation models assume that propagation occurs between two points over a slice of terrain. Use these models to calculate the pointtopoint path loss between sites over irregular terrain, including buildings.
Terrain models calculate path loss from freespace loss, terrain and obstacle diffraction, ground reflection, atmospheric refraction, and tropospheric scatter. They provide path loss estimates by combining physics with empirical data.
Model  Description  Frequency  Combinations  Limitations 

longleyrice  Also known as Irregular Terrain Model (ITM). For more information, see [4].  20 MHz to 20 GHz  Can be combined with rain, fog, and gas  Antenna height minimum is 0.5 m and maximum is 3000 m 
tirem  Terrain Integrated Rough Earth Model™  1 MHz to 1000 GHz  Can be combined with rain, fog, and gas 

Ray tracing models compute propagation paths using 3D environment geometry ([8],[9]). They determine the path loss and phase shift of each ray using electromagnetic analysis, including tracing the horizontal and vertical polarizations of a signal through the propagation path. The path loss includes both freespace loss and reflection losses. For each reflection, the model calculates losses on the horizontal and vertical polarizations by using the Fresnel equation, the incident angle, and the relative permittivity and conductivity of the surface material ([6],[7]) at the specified frequency.
While the other supported models compute single propagation paths, ray tracing models compute multiple propagation paths.
These models support both 3D outdoor and indoor environments.
Ray Tracing Method  Description  Frequency  Combinations  Limitations 

image 
 100 MHz to 100 GHz  Can be combined with rain, fog, and gas  Does not include effects from refraction, diffraction, and scattering 
shooting and bouncing rays (SBR) 
 100 MHz to 100 GHz  Can be combined with rain, fog, and gas  Does not include effects from refraction, diffraction, and scattering 
This illustration shows how the image method calculates the propagation path of a single reflection ray from a transmitter, Tx, to a receiver, Rx. The image method locates the image of Tx, Tx', with respect to a planar reflection surface. Then, the method connects Tx' and Rx with a line segment. If the line segment intersects the planar reflection surface, shown as Q in the illustration, then a valid path from Tx to Rx exists. The method determines paths with multiple reflections by recursively extending these steps.
This illustration shows how the SBR method calculates the propagation path of the same ray. The SBR method launches many rays from a geodesic sphere centered at Tx. Then, the method traces every ray from Tx as it reflects, diffracts, refracts, or scatters off surrounding objects. Note that the implementation considers only reflections. For each launched ray, the method surrounds Rx with a sphere, called a reception sphere, with a radius that is proportional to the angular separation of the launched rays and the distance the ray travels. If the ray intersects the sphere, then the model considers the ray a valid path from Tx to Rx.
[1] Sun, S.,Rapport, T.S., Thomas, T., Ghosh, A., Nguyen, H., Kovacs, I., Rodriguez, I., Koymen, O.,and Prartyka, A. "Investigation of prediction accuracy, sensitivity, and parameter stability of largescale propagation path loss models for 5G wireless communications." IEEE Transactions on Vehicular Technology, Vol.65, No 5, pp 28432860, May 2016.
[2] ITUR P.8406. "Attenuation due to cloud and fog." Radiocommunication Sector of ITU
[3] ITUR P.8383. "Specific attenuation model for rain for use in prediction methods." Radiocommunication Sector of ITU
[4] Hufford, George A., Anita G. Longley, and William A.Kissick. "A Guide to the Use of the ITS Irregular Terrain Model in the Area Prediction Mode." NTIA Report 82100. Pg7.
[5] ITUR P.67611. "Attenuation by atmospheric gases." Radiocommunication Sector of ITU
[6] ITUR P.20401. "Effects of Building Materials and Structures on Radiowave Propagation Above 100MHz." International Telecommunications Union  Radiocommunications Sector (ITUR). July 2015.
[7] ITUR P.5275. "Electrical characteristics of the surface of the Earth." International Telecommunications Union  Radiocommunications Sector (ITUR). August 2019.
[8] Yun, Zhengqing, and Magdy F. Iskander. “Ray Tracing for Radio Propagation Modeling: Principles and Applications.” IEEE Access 3 (2015): 1089–1100. https://doi.org/10.1109/ACCESS.2015.2453991.
[9] Schaubach, K.R., N.J. Davis, and T.S. Rappaport. “A Ray Tracing Method for Predicting Path Loss and Delay Spread in Microcellular Environments.” In [1992 Proceedings] Vehicular Technology Society 42nd VTS Conference  Frontiers of Technology, 932–35. Denver, CO, USA: IEEE, 1992. https://doi.org/10.1109/VETEC.1992.245274.