sigstrength
Description
returns the signal strength at the receiver site using the specified propagation
model. Specifying a propagation model is the same as specifying the
ss
= sigstrength(rx
,tx
,propmodel
)PropagationModel
namevalue argument.
specifies options using namevalue arguments, in addition to any combination of
arguments from the previous syntaxes. For example, ss
= sigstrength(___,Name=Value
)Type="efield"
returns the signal strength in electric field strength units (dBμV/m).
Examples
Received Power and Link Margin at Receiver
Create a transmitter site.
tx = txsite(Name="Fenway Park", ... Latitude=42.3467, ... Longitude=71.0972);
Create a receiver site with sensitivity defined in dBm.
rx = rxsite(Name="Bunker Hill Monument", ... Latitude=42.3763, ... Longitude=71.0611, ... ReceiverSensitivity=90);
Calculate the received power and link margin. Link margin is the difference between the receiver's sensitivity and the received power.
ss = sigstrength(rx,tx)
ss = 71.1414
margin = abs(rx.ReceiverSensitivity  ss)
margin = 18.8586
Signal Strength Using Ray Tracing Propagation Model
Launch Site Viewer with buildings in Chicago. For more information about the OpenStreetMap® file, see [1].
viewer = siteviewer(Buildings="chicago.osm");
Create a transmitter site on a building.
tx = txsite(Latitude=41.8800, ... Longitude=87.6295, ... TransmitterFrequency=2.5e9);
Create a receiver site near another building.
rx = rxsite(Latitude=41.881352, ... Longitude=87.629771, ... AntennaHeight=30);
Create a ray tracing propagation model, which MATLAB® represents using a RayTracing
object. By default, the propagation model uses the SBR method and finds propagation paths with up to two surface reflections.
pm = propagationModel("raytracing");
Calculate the signal strength using the receiver site, the transmitter site, and the propagation model.
ssTwoReflections = sigstrength(rx,tx,pm)
ssTwoReflections = 54.3151
Plot the propagation paths.
raytrace(tx,rx,pm)
Change the RayTracing
object to find paths with up to 5
reflections. Then, recalculate the signal strength.
pm.MaxNumReflections = 5; ssFiveReflections = sigstrength(rx,tx,pm)
ssFiveReflections = 53.3965
By default, RayTracing
objects use concrete terrain materials and building materials derived from the OpenStreetMap file. When the OpenStreetMap file does not specify materials, the model uses concrete. Change the building and terrain material types to model perfect electrical conductors.
pm.TerrainMaterial = "perfectreflector"; pm.BuildingsMaterial = "perfectreflector"; ssPerfect = sigstrength(rx,tx,pm)
ssPerfect = 38.9334
Plot the propagation paths for the updated propagation model.
raytrace(tx,rx,pm)
Appendix
[1] The OpenStreetMap file is downloaded from https://www.openstreetmap.org, which provides access to crowdsourced map data all over the world. The data is licensed under the Open Data Commons Open Database License (ODbL), https://opendatacommons.org/licenses/odbl/.
Input Arguments
rx
— Receiver site
rxsite
object  array of rxsite
objects
Receiver site, specified as an rxsite
object or an array of rxsite
objects.
tx
— Transmitter site
txsite
object  array of txsite
objects
Transmitter site, specified as a txsite
object or an array of txsite
objects.
propmodel
— Propagation model to use for path loss calculations
"longleyrice"
(default)  "freespace"
 "closein"
 "rain"
 "gas"
 "fog"
 "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"closein"
— Closein propagation model"longleyrice"
— LongleyRice 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 specifyingpropagationModel("raytracing","Method","image")
.
The default value depends on the coordinate system used by the input sites.
Coordinate System  Default propagation model value 

"geographic" 

"cartesian" 

Terrain propagation models, including "longleyrice"
and
"tirem"
, are only supported for sites with a
CoordinateSystem
value of
"geographic"
.
You can also specify the propagation model by using the
PropagationModel
namevalue pair argument.
NameValue Arguments
Specify optional pairs of arguments as
Name1=Value1,...,NameN=ValueN
, where Name
is
the argument name and Value
is the corresponding value.
Namevalue arguments must appear after other arguments, but the order of the
pairs does not matter.
Example: sigstrength(rx,tx,Type="efield")
returns the signal
strength in electric field strength units (dBμV/m).
Before R2021a, use commas to separate each name and value, and enclose
Name
in quotes.
Example: sigstrength(rx,tx,"Type","efield")
returns the signal
strength in electric field strength units (dBμV/m).
Type
— Type of signal strength to compute
"power"
(default)  "efield"
Type of signal strength to compute, specified as one of these options:
"power"
— The signal strength is in power units (dBm) of the signal at the mobile receiver input."efield"
— The signal strength is in electric field strength units (dBμV/m) of signal wave incident on the antenna.
Data Types: char
 string
PropagationModel
— Propagation model to use for path loss calculations
"freespace"
 "closein"
 "rain"
 "gas"
 "fog"
 "longleyrice"
 "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"closein"
— Closein propagation model"longleyrice"
— LongleyRice 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 specifyingpropagationModel("raytracing","Method","image")
.
The default value depends on the coordinate system used by the input sites.
Coordinate System  Default propagation model value 

"geographic" 

"cartesian" 

Terrain propagation models, including "longleyrice"
and
"tirem"
, are only supported for sites with a
CoordinateSystem
value of
"geographic"
.
Data Types: char
 string
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" 


"cartesian" 


^{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
ss
— Signal strength
MbyN array
Signal strength, returned as MbyN array, where M is the number of transmitter sites and N is the number of receiver sites.
The units of ss
depend on the value of the
Type
namevalue argument.
When you specify
Type
as"power"
, thenss
is in power units (dBm) of the signal at the mobile receiver input.When you specify
Type
as"efield"
, thenss
is in electric field strength units (dBμV/m) of signal wave incident on the antenna.
References
[1] International Telecommunications Union Radiocommunication Sector. Effects of Building Materials and Structures on Radiowave Propagation Above About 100MHz. Recommendation P.2040. ITUR, approved August 23, 2023. https://www.itu.int/rec/RRECP.2040/en.
[2] International Telecommunications Union Radiocommunication Sector. Electrical Characteristics of the Surface of the Earth. Recommendation P.527. ITUR, approved September 27, 2021. https://www.itu.int/rec/RRECP.527/en.
Version History
Introduced in R2019bR2024a: Ray tracing functions model materials using updated ITU recommendations
When calculating received power using ray tracing models, the
sigstrength
function models materials using the methods and
equations in International Telecommunication Union Recommendations (ITUR) P.20403
[1] and ITUR P.5275
through ITUR P.5276 [2].
In previous releases, the function used ITUR P.20401. As a result of these
changes, the sigstrength
function can return different values
in R2024a compared to previous releases.
R2023b: Perform ray tracing analysis with multiple materials in the same scene
The sigstrength
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 aRayTracing
propagation model object with itsSurfaceMaterial
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 aRayTracing
propagation model object with itsBuildingsMaterial
property set to"auto"
(the default).
The sigstrength
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 sigstrength
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
sigstrength
function.
R2023b: Ray tracing analysis with SBR method shows improved performance in complex scenes
The sigstrength
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 sigstrength
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 sigstrength
function.
R2022b: Ray tracing functions consider multipath interference
When calculating received power using ray tracing models, the
sigstrength
function now considers 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 sigstrength
function and
specify the propmodel
argument or
PropagationModel
namevalue argument as
"raytracing"
, the function uses the shooting and bouncing
rays (SBR) method and calculates up to two reflections. In previous releases, the
sigstrength
function uses the image method and calculates
up to one reflection.
To calculate received signal strength using the image method instead, create a
propagation model by using the propagationModel
function. Then, use the
sigstrength
function with the propagation model as input.
This example shows how to update your
code.
pm = propagationModel("raytracing","Method","image"); ss = sigstrength(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.
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