link

Display or compute communication link status

Syntax

link(rx,tx)

link(rx,tx,propmodel)

link(___,Name,Value)

status = link(___)

Description

link(rx,tx) displays a one-way point-to-point communication link between a receiver site and transmitter site in the current Site Viewer. The plot is color coded to identify the link success status.

link(rx,tx,propmodel) displays the communication link based on the specified propagation model.

link(___,Name,Value) displays a communication link using additional options specified by Name,Value pairs.

status = link(___) returns the success status of the communication link as true or false.

Examples

Communication Link Between Geographic Transmitter and Receiver

Create a transmitter site.

tx = txsite("Name","MathWorks", ...
        "Latitude",42.3001, ...
        "Longitude",-71.3503);

Create a receiver site with a sensitivity defined in dBm.

 rx = rxsite("Name","Boston", ...
        "Latitude",42.3601, ...
        "Longitude",-71.0589, ...
        "ReceiverSensitivity",-90);

Plot the communication link between the transmitter and the receiver.

link(rx,tx)

Communication Link Between Cartesian Transmitter and Receiver

Import and view an STL file. The file models a small conference room with one table and four chairs.

viewer = siteviewer('SceneModel','conferenceroom.stl');

Create a transmitter site near the upper corner of the room and a receiver site above the table. Specify the position using Cartesian coordinates in meters.

tx = txsite('cartesian', ...
    'AntennaPosition',[-1.46; -1.42; 2.1]);
rx = rxsite('cartesian', ...
    'AntennaPosition',[0.3; 0.3; 0.85]);

Plot the communication link between the transmitter and the receiver.

link(rx,tx)

Pan by left-clicking, zoom by right-clicking or by using the scroll wheel, and rotate the visualization by clicking the middle button and dragging or by pressing Ctrl and left-clicking and dragging.

Input Arguments

rx — Receiver site

rxsite object | array of rxsite objects

Receiver site, specified as a rxsite object. You can use array inputs to specify multiple sites.

tx — Transmitter site

txsite object | array of txsite objects

Transmitter site, specified as a txsite object. You can use array inputs to specify multiple sites.

propmodel — Propagation model to use for path loss calculations

"freespace" | "close-in" | "rain" | "gas" | "fog" | "longley-rice" | "raytracing" | propagation model created using propagationModel

Propagation model to use for the path loss calculations, specified as one of these options:

• "freespace" — Free space propagation model

• "rain" — Rain propagation model

• "gas" — Gas propagation model

• "fog" — Fog propagation model

• "close-in" — Close-in propagation model

• "longley-rice" — Longley-Rice propagation model

• "tirem" — TIREM™ propagation model

• "raytracing" — Ray tracing propagation model that uses the shooting and bouncing rays (SBR) method. When you specify a ray tracing model as input, the function incorporates multipath interference by using a phasor sum.

• A propagation model created using the propagationModel function. For example, you can create a ray tracing propagation model that uses the image method by specifying propagationModel("raytracing","Method","image").

The default value depends on the coordinate system used by the input sites.

Coordinate System	Default propagation model value
"geographic"	"longley-rice" when you use a terrain. "freespace" when you do not use a terrain.
"cartesian"	"freespace" when Map is set to none. "raytracing" when Map is set to the name of a glTF™ file, the name of an STL file, or a triangulation object. The default ray tracing model uses the shooting and bouncing rays (SBR) method.

Terrain propagation models, including "longley-rice" and "tirem", are only supported for sites with a CoordinateSystem value of "geographic".

You can also specify the propagation model by using the PropagationModel name-value pair argument.

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Before R2021a, use commas to separate each name and value, and enclose Name in quotes.

Example: "Type","power"

PropagationModel — Propagation model to use for path loss calculations

"freespace" | "close-in" | "rain" | "gas" | "fog" | "longley-rice" | "raytracing" | propagation model created using propagationModel

Propagation model to use for the path loss calculations, specified as one of these options:

• "freespace" — Free space propagation model

• "rain" — Rain propagation model

• "gas" — Gas propagation model

• "fog" — Fog propagation model

• "close-in" — Close-in propagation model

• "longley-rice" — Longley-Rice propagation model

• "tirem" — TIREM propagation model

• "raytracing" — Ray tracing propagation model that uses the shooting and bouncing rays (SBR) method. When you specify a ray tracing model as input, the function incorporates multipath interference by using a phasor sum.

• A propagation model created using the propagationModel function. For example, you can create a ray tracing propagation model that uses the image method by specifying propagationModel("raytracing","Method","image").

The default value depends on the coordinate system used by the input sites.

Coordinate System	Default propagation model value
"geographic"	"longley-rice" when you use a terrain. "freespace" when you do not use a terrain.
"cartesian"	"freespace" when Map is set to none. "raytracing" when Map is set to the name of a glTF file, the name of an STL file, or a triangulation object. The default ray tracing model uses the shooting and bouncing rays (SBR) method.

Terrain propagation models, including "longley-rice" and "tirem", are only supported for sites with a CoordinateSystem value of "geographic".

Data Types: char | string

SuccessColor — Color of successful links

"green" (default) | RGB triplet | character vector | string scalar

Color of successful links, specified as one of these options:

• An RGB triplet whose elements specify the intensities of the red, green, and blue components of the color. The intensities must be in the range [0,1]; for example, [0.4 0.6 0.7].

• A character vector such as "red" or "r".

• A string scalar such as "red" or "r".

This table contains the color names and equivalent RGB triplets for some common colors.

Color Name	Short Name	RGB Triplet	Appearance
"red"	"r"	[1 0 0]
"green"	"g"	[0 1 0]
"blue"	"b"	[0 0 1]
"cyan"	"c"	[0 1 1]
"magenta"	"m"	[1 0 1]
"yellow"	"y"	[1 1 0]
"black"	"k"	[0 0 0]
"white"	"w"	[1 1 1]

Data Types: char | string | double

FailColor — Color of unsuccessful links

"red" (default) | RGB triplet | character vector | string scalar

Color of unsuccessful links, specified as one of these options:

• An RGB triplet whose elements specify the intensities of the red, green, and blue components of the color. The intensities must be in the range [0,1]; for example, [0.4 0.6 0.7].

• A character vector such as "red" or "r".

• A string scalar such as "red" or "r".

This table contains the color names and equivalent RGB triplets for some common colors.

Color Name	Short Name	RGB Triplet	Appearance
"red"	"r"	[1 0 0]
"green"	"g"	[0 1 0]
"blue"	"b"	[0 0 1]
"cyan"	"c"	[0 1 1]
"magenta"	"m"	[1 0 1]
"yellow"	"y"	[1 1 0]
"black"	"k"	[0 0 0]
"white"	"w"	[1 1 1]

Data Types: char | string | double

Map — Map for visualization or surface data

siteviewer object | triangulation object | string scalar | character vector

Map for visualization or surface data, specified as a siteviewer object, a triangulation object, a string scalar, or a character vector. Valid and default values depend on the coordinate system.

Coordinate System	Valid map values	Default map value
"geographic"	A siteviewer objecta A terrain name, if the function is called with an output argument. Valid terrain names are "none", "gmted2010", or the name of the custom terrain data added using addCustomTerrain.	The current siteviewer object or a new siteviewer object if none are open "gmted2010", if the function is called with an output
"cartesian"	"none" A siteviewer object The name of a glTF file The name of an STL file A triangulation object	"none"
a Alignment of boundaries and region labels are a presentation of the feature provided by the data vendors and do not imply endorsement by MathWorks®.

In most cases, if you specify this argument as a value other than a siteviewer or "none", then you must also specify an output argument.

Data Types: char | string

Output Arguments

status — Success status of communication link

M-by-N array

Success status of communication links, returned as an M-by-N arrays. M is the number of transmitter sites and N is the number of receiver sites.

References

[1] Mohr, Peter J., Eite Tiesinga, David B. Newell, and Barry N. Taylor. “Codata Internationally Recommended 2022 Values of the Fundamental Physical Constants.” NIST, May 8, 2024. https://www.nist.gov/publications/codata-internationally-recommended-2022-values-fundamental-physical-constants.

Extended Capabilities

GPU Arrays

Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™. (since R2025a)

The link function supports ray tracing analysis on a GPU with these usage notes and limitations:

• The function runs on the GPU when you specify a RayTracing propagation model object as input and the UseGPU property of the object is "on" or "auto".

• For information about when the GPU can accelerate ray tracing analysis, see the UseGPU property of the RayTracing object.

• In some cases, the GPU and local CPU results can differ due to small differences in algorithms and hardware implementations.

For an example that shows how to perform ray tracing analysis on a GPU, see Accelerate Ray Tracing Analysis Using GPU.

Version History

Introduced in R2017b

R2025a: Ray tracing functions perform analysis using additional materials

When calculating communication links using ray tracing models, the link function performs the ray tracing analysis using additional materials. As a result of this change, depending on the materials in the scene, the link function can return different values in R2025a compared to previous releases.

R2025a: Ray tracing functions use improved algorithms

When calculating communication links using ray tracing models, the link function uses improved algorithms and constant values.

• The SBR method uses additional edges in the scene as candidates for diffraction. As a result, the SBR method can find more rays in R2025a compared to previous releases.

• When you specify transmitters and receivers that have polarized antennas from Antenna Toolbox™ or Phased Array System Toolbox™, the function calculates the phase shifts of rays using an improved algorithm that differently incorporates the far-field patterns of the antennas.

• The function uses the constant values that are recommended by the 2022 Committee on Data of the International Science Council (CODATA) adjustment of fundamental constants [1]. In previous releases, the function used constant values from International Telecommunication Union Recommendations (ITU-R) P.2040 and P.527.

As a result of these changes, the link function can return different values in R2025a compared to previous releases.

R2023b: Perform ray tracing analysis with multiple materials in the same scene

The link function performs ray tracing analysis with multiple materials in the same scene when:

• You create the scene from a glTF file, and specify the propmodel input argument as "raytracing" or a RayTracing propagation model object with its SurfaceMaterial property set to "auto" (the default).

• You create the scene from an OpenStreetMap^® file or a geospatial table, and you specify the propmodel input argument as "raytracing" or a RayTracing propagation model object with its BuildingsMaterial property set to "auto" (the default).

The link function performs the ray tracing analysis using the materials stored in the file or table. If the file or table does not specify materials, or if the file or table specifies a material that the ray tracing analysis does not support, then the function uses concrete instead of the absent or unsupported material.

As a result, the link function can return different values in R2023b compared to previous releases. To avoid using the materials stored in the file or table, create a RayTracing object (by using the propagationModel function) and set its SurfaceMaterial property to "plasterboard" and its BuildingsMaterial property to "concrete". Then, use the object as input to the link function.

R2023b: Ray tracing analysis with SBR method shows improved performance in complex scenes

The link function shows improved performance with complex scenes when you specify a RayTracing propagation model object that uses the shooting and bouncing rays (SBR) method as input.

The time that MATLAB^® requires to perform ray tracing analysis depends on the scene and on the properties of the RayTracing object, such as the AngularSeparation, MaxNumDiffractions, MaxNumReflections, MaxAbsolutePathLoss, and MaxRelativePathLoss properties. In some cases, with moderate values of the MaxAbsolutePathLoss and MaxRelativePathLoss properties, the ray tracing analysis can be more than 2x faster in R2023b than in R2023a.

R2023a: Ray tracing models discard paths based on path loss

Ray tracing propagation models discard propagation paths based on path loss thresholds. By default, when you specify the propmodel input argument as "raytracing" or a RayTracing object, the propagation model discards paths that are more than 40 dB weaker than the strongest path.

As a result, the link function can return different values in R2023a compared to previous releases. To avoid discarding paths based on relative path loss thresholds, create a RayTracing object (by using the propagationModel function) and set its MaxRelativePathLoss property to Inf. Then, use the object as input to the link function.

R2022b: Ray tracing functions consider multipath interference

When calculating received power using ray tracing models, the link function now incorporates multipath interference by using a phasor sum. In previous releases, the function used a power sum. As a result, the calculations in R2022b are more accurate than in previous releases.

R2021b: "raytracing" propagation models use SBR method

Starting in R2021b, when you use the link function and specify the propmodel argument or PropagationModel name-value argument as "raytracing", the function uses the shooting and bouncing rays (SBR) method and calculates up to two reflections. In previous releases, the link function uses the image method and calculates up to one reflection.

To display or compute communication link status using the image method instead, create a propagation model by using the propagationModel function. Then, use the link function with the propagation model as input. This example shows how to update your code.

pm = propagationModel("raytracing","Method","image");
link(rx,tx,pm)

For information about the SBR and image methods, see Choose a Propagation Model.

Starting in R2021b, all RF Propagation functions use the SBR method by default and calculate up to two reflections. For more information, see Default modeling method is shooting and bouncing rays method.