doppler
Construct Doppler spectrum structure
Description
s = doppler(
constructs
a Doppler spectrum structure of type specType
)specType
for
use with a fading channel System object. The returned structure, s
,
has default values for its dependent fields.
s = doppler(
constructs
a Doppler spectrum structure of type specType
, fieldValue
)specType
for
use with a fading channel System object. The returned structure, s
,
has its dependent field specified to fieldValue
.
s = doppler('BiGaussian',
constructs
a BiGaussian Doppler spectrum structure for use with a fading channel
System object. The returned structure, Name,Value
)s
, has dependent
fields specified by Name,Value
pair arguments.
Examples
Construct a Flat Doppler Spectrum Structure
Construct a flat Doppler structure variable for use with channel objects such as comm.RayleighChannel
.
Invoke the doppler
function to create a flat Doppler structure variable.
s = doppler('Flat')
s = struct with fields:
SpectrumType: 'Flat'
Create a Bell Doppler Structure Variable
Use the doppler
function to create a Doppler structure variable having the Bell spectrum.
s = doppler('Bell')
s = struct with fields:
SpectrumType: 'Bell'
Coefficient: 9
Construct a Rounded Doppler Spectrum Structure with Specified Polynomial
Specify the coefficients of the Doppler spectrum structure variable.
Construct a Rounded Doppler spectrum structure with coefficients a0
, a2
, and a4
set to 2
, 6
, and 1
, respectively.
s = doppler('Rounded', [2, 6, 1])
s = struct with fields:
SpectrumType: 'Rounded'
Polynomial: [2 6 1]
Construct a BiGaussian Doppler Spectrum Structure with Specified Field Values
Use the doppler
function to create a Doppler spectrum structure with the parameters specified for a BiGaussian spectrum.
s = doppler('BiGaussian','NormalizedCenterFrequencies', ... [.1 .85],'PowerGains',[1 2])
s = struct with fields:
SpectrumType: 'BiGaussian'
NormalizedStandardDeviations: [0.7071 0.7071]
NormalizedCenterFrequencies: [0.1000 0.8500]
PowerGains: [1 2]
The NormalizedStandardDeviations
field is set to the default value. The NormalizedCenterFrequencies
, and PowerGains
fields are set to the values specified from the input arguments.
Input Arguments
specType
— Spectrum type of Doppler spectrum structure for use with fading channel System object
'Jakes'
| 'Flat'
| 'Rounded'
| 'Bell'
| 'Asymmetric Jakes'
| 'Restricted Jakes'
| 'Gaussian'
| 'BiGaussian'
The spectrum type of a Doppler spectrum structure for use with a fading channel System object. Specify this value as a character vector.
The analytical expression for each Doppler spectrum type is described in the Algorithms section.
Data Types: char
fieldValue
— Value of dependent field of Doppler spectrum structure
scalar | vector
The value of the dependent field of the Doppler spectrum structure,
specified as a scalar or vector of built-in data type. If you do not
specify fieldValue
, the dependent fields of the
spectrum type use the default values.
Spectrum Type | Dependent Field | Description | Default Value |
---|---|---|---|
Jakes | — | — | — |
Flat | — | — | — |
Rounded | Polynomial | 1-by-3 vector of real finite values, representing the
polynomial coefficients, a0, a2 and
a4 | [1 -1.72 0.785] |
Bell | Coefficient | Nonnegative, finite, real scalar representing the Bell spectrum coefficient | 9 |
Asymmetric Jakes | NormalizedFrequencyInterval | 1-by-2 vector of real values between –1 and 1, inclusive, representing the minimum and maximum normalized Doppler shifts | [0 1] |
Restricted Jakes | NormalizedFrequencyInterval | 1-by-2 vector of real values between 0 and 1, inclusive, representing the minimum and maximum normalized Doppler shifts | [0 1] |
Gaussian | NormalizedStandardDeviation | Normalized standard deviation of the Gaussian Doppler spectrum, specified as a positive, finite, real scalar | 0.7071 |
BiGaussian | NormalizedStandardDeviations | Normalized standard deviations of the BiGaussian Doppler spectrum, specified as a positive, finite, real 1-by-2 vector | [0.7071 0.7071] |
NormalizedCenterFreqencies | Normalized center frequencies of the BiGaussian Doppler spectrum specified as a real 1-by-2 vector whose elements fall between –1 and 1 | [0 0] | |
PowerGains | Linear power gains of the BiGaussian Doppler spectrum specified as a real nonnegative 1-by-2 vector | [0.5 0.5] |
Data Types: double
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: s=doppler('BiGaussian', 'NormalizedStandardDeviations',
[.8 .75], 'NormalizedCenterFrequencies', [-.8 0], 'PowerGains', [.6
.6])
NormalizedStandardDeviations
— Normalized standard deviations of first and second Gaussian functions
[1/sqrt(2) 1/sqrt(2)]
(default) | 1-by-2 positive numeric vector
The normalized standard deviation of the first and second Gaussian functions. You can specify this value as a 1-by-2 positive numeric vector, of built-in data types.
When you do not specify this dependent field, the default value
is [1/sqrt(2) 1/sqrt(2)]
.
Data Types: double
NormalizedCenterFrequencies
— Normalized center frequencies of first and second Gaussian functions
[0 0]
(default) | 1-by-2 numeric vector
The normalized center frequencies of the first and second Gaussian functions. You can specify this value as a 1-by-2 numeric vector of real values between –1 and 1, of built-in data types.
When you do not specify this dependent field, the default value
is [0 0]
.
Data Types: double
PowerGains
— Power gains of first and second Gaussian functions
[0.5 0.5]
(default) | 1-by-2 numeric vector
The power gains of the first and second Gaussian functions. You can specify this value as a 1-by-2 nonnegative numeric vector of built-in data types.
When you do not specify this dependent field, the default value
is [0.5 0.5]
.
Data Types: double
Algorithms
The following algorithms represent the analytical expressions for each Doppler spectrum type.
In each case, denotes the maximum Doppler shift
(MaximumDopplerShift
property) of the associated fading channel
System object.
Jakes
The theoretical Jakes
Doppler spectrum, S(f) has
the analytic formula
Flat
The theoretical Flat
Doppler spectrum, S(f) has
the analytic formula
Rounded
The theoretical Rounded
Doppler spectrum, S(f) has the
analytic formula
where
and you can specify [] in the dependent field, polynomial
.
Bell
The theoretical Bell
Doppler spectrum, S(f) has
the analytic formula
where
You can specify A in the dependent
field, coefficient
.
Asymmetric Jakes
The theoretical Asymmetric Jakes
Doppler spectrum, S(f)
has the analytic formula
where you can specify / and / in the dependent field,
NormalizedFrequencyInterval
.
Restricted Jakes
The theoretical Restricted Jakes
Doppler spectrum, S(f)
has the analytic formula
where
where you can specify / and / in the dependent field,
NormalizedFrequencyInterval
.
Gaussian
The theoretical Gaussian
Doppler spectrum, S(f) has
the analytic formula
You can specify in
the dependent field, NormalizedStandardDeviation
.
BiGaussian
The theoretical BiGaussian
Doppler spectrum, S(f) has
the analytic formula
where is a normalization coefficient.
You can specify / and / in the NormalizedStandardDeviations
dependent
field.
You can specify / and / in the NormalizedCenterFrequencies
dependent
field.
and are power gains that you can specify in the
PowerGains
dependent field.
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.
Usage notes and limitations:
All inputs must be constants. Expressions or variables are allowed if their values do not change.
Version History
Introduced in R2007a
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