nrCDLChannel

Model CDL MIMO channel

Description

The nrCDLChannel System object™ models a clustered delay line (CDL) multiple-input multiple-output (MIMO) link-level fading channel. The object implements these aspects of TR 38.901 [1]:

• Section 7.7.1: CDL models

• Section 7.7.3: Scaling of delays

• Section 7.7.5.1: Scaling of angles

• Section 7.7.6: K-factor for LOS channel models

• Section 7.6.10: Dual mobility (since R2023b)

The object enables CDL channel filtering by default. When CDL channel filtering is enabled, you can send an input signal through the channel to obtain the channel-impaired signal, path gains of the fading process, and sample times of the channel snapshots. Alternatively, if you disable channel filtering, you can obtain the path gains and sample times without sending an input signal through the channel. Use the ChannelFiltering property to enable or disable CDL channel filtering. For an overview of how the object properties configure CDL channel filtering and channel coefficients generation, see Internal Architecture of CDL Channel Model.

To use the CDL MIMO channel model:

1. Create the nrCDLChannel object and set its properties.

2. Call the object with arguments, as if it were a function.

To learn more about how System objects work, see What Are System Objects?

Creation

Syntax

cdl = nrCDLChannel

cdl = nrCDLChannel(Name=Value)

cdl = nrCDLChannel(DelayProfile='Custom',InitialDelayProfile=profile,DelaySpread=spread,KFactor=K)

Description

cdl = nrCDLChannel creates a CDL MIMO channel System object.

cdl = nrCDLChannel(Name=Value) creates the object with properties set by using one or more name-value arguments. For example, DelayProfile='CDL-D' creates the channel object with CDL-D delay profile.

cdl = nrCDLChannel(DelayProfile='Custom',InitialDelayProfile=profile,DelaySpread=spread,KFactor=K) creates the object with customized channel characteristics that are initialized from the predefined delay profile, profile. Specify the profile input as 'CDL-A', 'CDL-B', 'CDL-C', 'CDL-D', or 'CDL-E'. (since R2023b)

When you use this syntax:

• The DelayProfile object property is set to 'Custom' and the AnglesAoD, AnglesAoA, AnglesZoD, AnglesZoA, HasLOSCluster, KFactorFirstCluster, AngleSpreads, and XPR object properties are set to values that are defined for the specified predefined delay profile in TR 38.901 Tables 7.7.1-1 to 7.7.1-5 [1].

• The values in the PathDelays and AveragePathGains properties are scaled from the initial table values to obtain the desired channel delay spread, specified by spread in seconds, and K-factor, specified by K in dB, respectively. Specify the optional spread and K inputs as a numeric scalar. The spread input defaults to 30e-9 when not specified. The K input defaults to the K-factor values in TR 38.901 Tables 7.7.1-4 to 7.7.1-5 (no K-factor scaling). The K input applies only when the profile input is set to 'CDL-D' or 'CDL-E'.

Properties

Unless otherwise indicated, properties are nontunable, which means you cannot change their values after calling the object. Objects lock when you call them, and the release function unlocks them.

If a property is tunable, you can change its value at any time.

For more information on changing property values, see System Design in MATLAB Using System Objects.

Delay Profile Selection

The delay profile selection determines which delay profile configuration properties are applicable to the channel.

DelayProfile — CDL delay profile

'CDL-A' (default) | 'CDL-B' | 'CDL-C' | 'CDL-D' | 'CDL-E' | 'Custom'

CDL delay profile from TR 38.901 Section 7.7.1, Tables 7.7.1-1 to 7.7.1-5, specified as one of these options:

• 'CDL-A', 'CDL-B', 'CDL-C', 'CDL-D', 'CDL-E' — To configure channel parameters that are specific to these predefined delay profiles, see the Predefined Delay Profile section.

• 'Custom' — To configure channel parameters that are specific to custom delay profiles, see the Custom Delay Profile section.

Data Types: char | string

Predefined Delay Profile

These properties configure channel parameters that are specific to predefined channel profiles, that is, when you set the DelayProfile to 'CDL-A', 'CDL-B', 'CDL-C', 'CDL-D', or 'CDL-E'.

DelaySpread — Desired RMS delay spread in seconds

3.000e-8 (default) | nonnegative real number

Desired RMS delay spread in seconds, specified as a nonnegative real number. For examples of desired RMS delay spreads, DSdesired, see TR 38.901 Section 7.7.3 and Tables 7.7.3-1 and 7.7.3-2. The default value is 30 nanoseconds.

Dependencies

To enable this property, set DelayProfile to 'CDL-A', 'CDL-B', 'CDL-C', 'CDL-D', or 'CDL-E'. This property does not apply for custom delay profiles.

Data Types: double

KFactorScaling — K-factor scaling

false (default) | true

K-factor scaling, specified as false or true. When set to true, the KFactor property specifies the desired K-factor and the object applies K-factor scaling as described in TR 38.901 Section 7.7.6.

Note

K-factor scaling modifies both the path delays and the path powers.

Dependencies

To enable this property, set DelayProfile to 'CDL-D' or 'CDL-E'.

Data Types: double

KFactor — Desired K-factor for scaling

9.0 (default) | numeric scalar

Desired K-factor for scaling in dB, specified as a numeric scalar. For typical K-factor values, see TR 38.901 Section 7.7.6 and Table 7.5-6.

Note

• K-factor scaling modifies both the path delays and path powers.

• K-factor applies to the overall delay profile. Specifically, the K-factor before the scaling is Kmodel, as described in TR 38.901 Section 7.7.6. Kmodel is the ratio of the power of the first path LOS to the total power of all the Laplacian clusters, including the Laplacian part of the first cluster.

Dependencies

To enable this property, set KFactorScaling to true.

Data Types: double

AngleScaling — Apply scaling of angles

false (default) | true

Apply scaling of angles, specified as false or true according to TR 38.901 Section 7.7.5.1. When set to true, the AngleSpreads and MeanAngles properties define the scaling of angles.

Dependencies

To enable this property, set DelayProfile to 'CDL-A', 'CDL-B', 'CDL-C', 'CDL-D', or 'CDL-E'. This property does not apply for custom delay profiles.

Data Types: logical

MeanAngles — Scaled mean angles in degrees

[0.0 0.0 0.0 0.0] (default) | four-element row vector

Scaled mean angles in degrees, specified as a four-element row vector of the form [AoD AoA ZoD ZoA].

• AoD is the mean azimuth of departure angles after scaling.

• AoA is the mean azimuth of arrival angles after scaling.

• ZoD is the mean zenith of departure angles after scaling.

• ZoA is the mean zenith of arrival angles after scaling.

Use this vector to specify the desired mean angles of the channel used for angle scaling ($${\mu }_{\Phi ,\text{desired}}$$), as described in TR 38.901 Section 7.7.5.1.

Dependencies

To enable this property, set AngleScaling to true.

Data Types: double

Custom Delay Profile

These properties configure channel parameters that are specific to custom delay profiles, that is, when you set the DelayProfile to 'Custom'.

PathDelays — Discrete path delays in seconds

0.0 (default) | numeric scalar | row vector

Discrete path delays in seconds, specified as a numeric scalar or row vector. AveragePathGains and PathDelays must have the same size.

Dependencies

To enable this property, set DelayProfile to 'Custom'.

Data Types: double

AveragePathGains — Average path gains in dB

0.0 (default) | numeric scalar | row vector

Average path gains in dB, also referred to as cluster powers in TR 38.901, specified as a numeric scalar or row vector. AveragePathGains and PathDelays must have the same size.

Dependencies

To enable this property, set DelayProfile to 'Custom'.

Data Types: double

AnglesAoA — Azimuth of arrival angle in degrees

0.0 (default) | numeric scalar | row vector

Azimuth of arrival angle in degrees, specified as a numeric scalar or row vector. The vector elements specify the angles for each cluster.

Dependencies

To enable this property, set DelayProfile to 'Custom'.

Data Types: double

AnglesAoD — Azimuth of departure angle in degrees

0.0 (default) | numeric scalar | row vector

Azimuth of departure angle in degrees, specified as a numeric scalar or row vector. The vector elements specify the angles for each cluster.

Dependencies

To enable this property, set DelayProfile to 'Custom'.

Data Types: double

AnglesZoA — Zenith of arrival angle in degrees

0.0 (default) | numeric scalar | row vector

Zenith of arrival angle in degrees, specified as a numeric scalar or row vector. The vector elements specify the angles for each cluster.

Dependencies

To enable this property, set DelayProfile to 'Custom'.

Data Types: double

AnglesZoD — Zenith of departure angle in degrees

0.0 (default) | numeric scalar | row vector

Zenith of departure angle in degrees, specified as a numeric scalar or row vector. The vector elements specify the angles for each cluster.

Dependencies

To enable this property, set DelayProfile to 'Custom'.

Data Types: double

HasLOSCluster — Line of sight cluster of the delay profile

false (default) | true

Line of sight (LOS) cluster of the delay profile, specified as false or true. The PathDelays, AveragePathGains, AnglesAoA, AnglesAoD, AnglesZoA, and AnglesZoD properties define the delay profile. To enable the LOS cluster of the delay profile, set HasLOSCluster to true.

Dependencies

To enable this property, set DelayProfile to 'Custom'.

Data Types: logical

KFactorFirstCluster — K-factor in first cluster of delay profile in dB

13.3 (default) | numeric scalar

K-factor in the first cluster of the delay profile in dB, specified as a numeric scalar. The default value corresponds to the K-factor in the first cluster of CDL-D as defined in TR 38.901 Section 7.7.1, Table 7.7.1-4.

Dependencies

To enable this property, set DelayProfile to 'Custom' and HasLOSCluster to true.

Data Types: double

AngleSpreads — Scaled or cluster-wise RMS angle spreads in degrees

[5.0 11.0 3.0 3.0] (default) | four-element row vector

Scaled or cluster-wise root mean square (RMS) angle spreads in degrees, specified as a four-element row vector in one of these forms:

• [ASD ASA ZSD ZSA] — Use this vector to specify the desired RMS angle spreads of the channel, as described in TR 38.901 Section 7.7.5.1 (AS_desired), where:

  • ASD is the RMS azimuth spread of departure angles.

  • ASA is the RMS azimuth spread of arrival angles.

  • ZSD is the RMS zenith spread of departure angles.

  • ZSA is the RMS zenith spread of arrival angles.

  To use this form, set AngleScaling to true and DelayProfile to 'CDL-A', 'CDL-B', 'CDL-C', 'CDL-D', or 'CDL-E'.

• [C_ASD C_ASA C_ZSD C_ZSA] — Use this vector to specify cluster-wise RMS angle spreads for scaling ray offset angles within a cluster, as described in TR 38.901 Section 7.7.1, Step1, where:

  • C_ASD is the cluster-wise RMS azimuth spread of departure angles.

  • C_ASA is the cluster-wise RMS azimuth spread of arrival angles.

  • C_ZSD is the cluster-wise RMS zenith spread of departure angles.

  • C_ZSA is the cluster-wise RMS zenith spread of arrival angles.

  To use this form, set DelayProfile to 'Custom'. Based on TR 38.901 Section 7.7.5.1, the object does not perform angle scaling in this case.

The default value corresponds to the default cluster-wise angle spreads of CDL-A as defined in TR 38.901 Section 7.7.1 Table 7.7.1-1.

Dependencies

To enable this property, set DelayProfile to 'Custom' or AngleScaling to true.

Data Types: double

RayCoupling — Coupling of departure and arrival rays within a cluster

'Random' (default) | N-by-M-by-3 numeric array

Coupling of departure and arrival rays within a cluster for azimuth and elevation, specified as one of these values:

• 'Random' — The object randomly couples the rays, as defined in TR 38.901 Section 7.5 Step 8, using the random number stream specified by the RandomStream property.

• N-by-M-by-3 numeric array — Use this array to explicitly define the ray coupling. N is the number of clusters, equal to the number of path delays, specified by the PathDelays property. M is the number of rays per cluster, equal to 20. The three N-by-M planes, in the third dimension, correspond to the AoD/AoA, ZoD/ZoA, and AoD/ZoD ray couplings, respectively. Each row in each N-by-M plane specifies the ray coupling within the corresponding cluster by using a permutation of ray indices from 1 to M.

  Note

  • N is the number of clusters before any splitting into subclusters (see the NumStrongestClusters property).

  • N does not count the LOS cluster that is specified by the HasLOSCluster property.

Dependencies

To enable this property, set DelayProfile to 'Custom'.

Data Types: double | char | string

XPR — Cross-polarization power ratio in dB

10.0 (default) | numeric scalar | N-by-M numeric matrix

Cross-polarization power ratio in dB, specified as a numeric scalar or an N-by-M numeric matrix. N is the number of clusters, equal to the number of path delays, specified by the PathDelays property. M is the number of rays per cluster, equal to 20. The default value corresponds to the cluster-wise cross-polarization power ratio of CDL-A, as defined in TR 38.901 Section 7.7.1, Table 7.7.1-1.

Note

• N is the number of clusters before any splitting into subclusters (see the NumStrongestClusters property).

• N does not count the LOS cluster that is specified by the HasLOSCluster property.

Dependencies

To enable this property, set DelayProfile to 'Custom'.

Data Types: double

InitialPhases — Initial phases in degrees

'Random' (default) | N-by-M-by-4 numeric array

Initial phases of all rays for the four polarization combinations in degrees, specified as one of these values:

• 'Random' — The object draws uniformly distributed random phases, as defined in TR 38.901 Section 7.5 Step 10, using the random number stream specified by the RandomStream property.

• N-by-M-by-4 numeric array — Use this option to explicitly define the initial phases. N is the number of clusters, equal to the number of path delays, specified by the PathDelays property. M is the number of rays per cluster, equal to 20. The four N-by-M planes, in the third dimension, correspond to the θ/θ, θ/ϕ, ϕ/θ, ϕ/ϕ polarization combinations, respectively.

  Note

  • N is the number of clusters before any splitting into subclusters (see the NumStrongestClusters property).

  • N does not count the LOS cluster that is specified by the HasLOSCluster property.

Dependencies

To enable this property, set DelayProfile to 'Custom'.

Data Types: double | char | string

NumStrongestClusters — Number of strongest clusters to split into subclusters

0 (default) | nonnegative integer

Number of strongest clusters to split into subclusters, specified as a nonnegative integer. See TR 38.901 Section 7.5, Step 11.

Dependencies

To enable this property, set DelayProfile to 'Custom'.

Data Types: double

ClusterDelaySpread — Cluster delay spread in seconds

3.90625e-9 (default) | nonnegative real number

Cluster delay spread in seconds, specified as a nonnegative real number. Use this property to specify the delay offset between subclusters for clusters split into subclusters. See TR 38.901 Section 7.5, Step 11.

Dependencies

To enable this property, set DelayProfile to 'Custom' and NumStrongestClusters to a value greater than zero.

Data Types: double

Antenna Array

These properties configure geometric aspects of the channel.

TransmitAntennaArray — Transmit antenna array characteristics

structure (default) | phased array

Transmit antenna array characteristics, specified as a structure or a phased array (requires Phased Array System Toolbox™).

Phased arrays enable you to specify different antenna array configurations, including predefined and custom antenna elements. You can design custom antenna elements by using Phased Array System Toolbox or Antenna Toolbox™ features. To specify custom antenna elements in a 5G rectangular multipanel array, as defined in TR 38.901 Section 7.3, use the phased.NRRectangularPanelArray (Phased Array System Toolbox) object. For an overview of phased arrays, see Array Geometries and Analysis (Phased Array System Toolbox).

When specified as a structure, this property contains these fields:

Parameter Field	Values	Description
Size	[2 2 2 1 1] (default) row vector	Size of antenna array [M N P Mg Ng], where: M and N are the number of rows and columns in the antenna array, respectively. P is the number of polarizations (1 or 2). Mg and Ng are the number of row and column array panels, respectively. The nrCDLChannel System object maps the input signal signalIn to the antenna array elements panel-wise, in the order that a 5-D array of size M-by-N-by-P-by-Mg-by-Ng is linearly indexed across the first dimension to the last. For example, this figure shows how the object maps the input signal signalIn to an antenna array of size [2 3 2 2 2]. The antenna array consists of 2-by-2 antenna panels of 2-by-3 elements with two polarizations. The object maps the first M = 2 columns of the input signal (s1 and s2) to the first column of antenna elements with the first polarization angle of the first panel. The next M = 2 columns of the input signal (s3 and s4) are mapped to the next column of antenna elements, and so on. Following this pattern, the object maps the first M × N = 6 columns of the input signal (s1 to s6) to the antenna elements with the first polarization angle of the complete first panel. Similarly, the next six columns of the input signal (s7 to s12) are mapped to the antenna elements with the second polarization angle of the first panel. Subsequent sets of M × N × P = 12 columns of the input signal (s13 to s24, s25 to s36, s37 to s48) are mapped to consecutive panels, taking panel rows first, then panel columns.
ElementSpacing	[0.5 0.5 1.0 1.0] (default) row vector	Element spacing, in wavelengths, specified as a row vector of the form [λv λh dgv dgh]. The vector elements represent the vertical and horizontal element spacing and the vertical and horizontal panel spacing, respectively. The panel spacing is measured from the center of the panels.
PolarizationAngles	[45 -45] (default) row vector	Polarization angles in degrees, specified as a row vector of the form [θ ρ].
Orientation (to be removed)	[0; 0; 0](default) column vector	Note This field will be removed in a future release. Use the TransmitArrayOrientation property instead. Mechanical orientation of the array, in degrees, specified as a column vector of the form [α; β; γ]. The vector elements specify the bearing, downtilt, and slant, respectively. The default value indicates that the broadside direction of the array points to the positive x-axis.
Element	'38.901' (default) 'isotropic'	Antenna element radiation pattern as described in TR 38.901 Section 7.3. (Note that TR 38.901 supersedes TR 38.900.)
PolarizationModel	'Model-2' (default) 'Model-1'	Model that determines the radiation field patterns based on a defined radiation power pattern. For more information, see TR 38.901 Section 7.3.2.

TransmitArrayOrientation — Mechanical orientation of transmit antenna array

[0; 0; 0] (default) | three-element numeric column vector

Mechanical orientation of the transmit antenna array, specified as a three-element numeric column vector of the form [α; β; γ]. The vector elements specify the bearing, downtilt, and slant rotation angles in degrees, respectively, as specified in TR 38.901 Section 7.1.3. The object applies these rotation angles relative to the default array orientation in the local coordinate system. The default array orientation, corresponding to the value [0; 0; 0], depends on the TransmitAntennaArray property.

• If you specify the TransmitAntennaArray property as a structure (default), in the default array orientation, the broadside direction points to the positive x-axis.

• If you specify the TransmitAntennaArray property as a phased array (requires Phased Array System Toolbox), you can configure the default array orientation by setting the relevant array properties of the specified phased array object.

To visualize and evaluate the resulting array orientation, call the displayChannel function on the nrCDLChannel channel model.

For an example of orienting transmit and receive antennas toward each other, see Orient Transmit and Receive Antennas Using LOS Path Angles.

Data Types: double

ReceiveAntennaArray — Receive antenna array characteristics

structure (default) | phased array

Receive antenna array characteristics, specified as a structure or a phased array (requires Phased Array System Toolbox).

Phased arrays enable you to specify different antenna array configurations, including predefined and custom antenna elements. You can design custom antenna elements by using Phased Array System Toolbox or Antenna Toolbox features. To specify custom antenna elements in a 5G rectangular multipanel array, as defined in TR 38.901 Section 7.3, use the phased.NRRectangularPanelArray (Phased Array System Toolbox) object. For an overview of phased arrays, see Array Geometries and Analysis (Phased Array System Toolbox).

When specified as a structure, this property contains these fields:

Parameter Field	Values	Description
Size	[1 1 2 1 1] (default) row vector	Size of antenna array [M N P Mg Ng], where: M and N are the number of rows and columns in the antenna array, respectively. P is the number of polarizations (1 or 2). Mg and Ng are the number of row and column array panels, respectively. The nrCDLChannel System object maps the antenna array elements to the output signal signalOut panel-wise, in the order that a 5-D array of size M-by-N-by-P-by-Mg-by-Ng is linearly indexed across the first dimension to the last. For example, this figure shows how the object maps an antenna array of size [2 3 2 2 2] to the output signal signalOut. The antenna array consists of 2-by-2 antenna panels of 2-by-3 elements with two polarizations. The first column of antenna elements with the first polarization angle of the first panel are mapped to the first M = 2 columns of the output signal (s1 and s2). The next column of antenna elements are mapped to the next M = 2 columns of the output signal (s3 and s4), and so on. Following this pattern, the object maps the antenna elements with the first polarization angle of the complete first panel to the first M × N = 6 columns of the output signal (s1 to s6). Similarly, the antenna elements with the second polarization angle of the first panel are mapped to the next six columns of the output signal (s7 to s12). Consecutive panels are mapped to subsequent sets of M × N × P = 12 columns of the output signal (s13 to s24, s25 to s36, s37 to s48), taking panel rows first, then panel columns.
ElementSpacing	[0.5 0.5 0.5 0.5] (default) row vector	Element spacing, in wavelengths, specified as a row vector of the form [λv λh dgv dgh]. The vector elements represent the vertical and horizontal element spacing and the vertical and horizontal panel spacing, respectively. The panel spacing is measured from the center of the panels.
PolarizationAngles	[0 90] (default) row vector	Polarization angles in degrees, specified as a row vector of the form [θ ρ].
Orientation (to be removed)	[0; 0; 0](default) column vector	Note This field will be removed in a future release. Use the ReceiveArrayOrientation property instead. Mechanical orientation of the array, in degrees, specified as a column vector of the form [α; β; γ]. The vector elements specify the bearing, downtilt, and slant, respectively. The default value indicates that the broadside direction of the array points to the positive x-axis.
Element	'isotropic' (default) '38.901'	Antenna element radiation pattern as described in TR 38.901 Section 7.3. (Note that TR 38.901 supersedes TR 38.900.)
PolarizationModel	'Model-2' (default) 'Model-1'	Model that determines the radiation field patterns based on a defined radiation power pattern. For more information, see TR 38.901 Section 7.3.2.

ReceiveArrayOrientation — Mechanical orientation of receive antenna array

[0; 0; 0] (default) | three-element numeric column vector

Mechanical orientation of the receive antenna array, specified as a three-element numeric column vector of the form [α; β; γ]. The vector elements specify the bearing, downtilt, and slant rotation angles in degrees, respectively, as specified in TR 38.901 Section 7.1.3. The object applies these rotation angles relative to the default array orientation in the local coordinate system. The default array orientation, corresponding to the value [0; 0; 0], depends on the ReceiveAntennaArray property.

• If you specify the ReceiveAntennaArray property as a structure (default), in the default array orientation, the broadside direction points to the positive x-axis.

• If you specify the ReceiveAntennaArray property as a phased array (requires Phased Array System Toolbox), you can configure the default array orientation by setting the relevant array properties of the specified phased array object.

To visualize and evaluate the resulting array orientation, call the displayChannel function on the nrCDLChannel channel model.

For an example of orienting transmit and receive antennas toward each other, see Orient Transmit and Receive Antennas Using LOS Path Angles.

Data Types: double

CarrierFrequency — Carrier frequency in Hz

4.0000e+09 (default) | nonnegative real number

Carrier frequency in Hz, specified as a nonnegative real number.

Data Types: double

Mobility

These properties configure how the user equipment (UE) moves.

MaximumDopplerShift — Maximum Doppler shift in Hz

5 (default) | nonnegative real number | 1-by-2 vector of nonnegative real numbers

Maximum Doppler shift in Hz, specified as one of these values:

• Nonnegative real number — This value specifies the maximum Doppler shift of the receiver. If the UTDirectionOfTravel property is specified as a 2-by-2 matrix, this value specifies the maximum Doppler shift of the receiver as well as the transmitter.

• 1-by-2 vector of nonnegative real numbers of the form [Rx Tx] — Rx and Tx specify the maximum Doppler shift of the receiver and transmitter, respectively. (since R2023b)

This property applies to all channel paths. When the maximum Doppler shift is set to 0, the channel remains static for the entire input. To generate a new channel realization, reset the object by calling the reset function.

Data Types: double

UTDirectionOfTravel — User terminal direction of travel in degrees

[0; 90] (default) | 2-by-1 vector of real numbers | 2-by-2 matrix of real numbers

User terminal (or user equipment) direction of travel in degrees, specified as one of these values:

• 2-by-1 vector of real numbers of the form [Rx_A; Rx_Z] — Rx_A and Rx_Z specify the azimuth and zenith of the direction of travel of the receiver UE, respectively. If the MaximumDopplerShift property is specified as a 1-by-2 vector, Rx_A and Rx_Z specify the azimuth and zenith of the direction of travel of the receiver UE as well as the transmitter UE, respectively.

• 2-by-2 matrix of real numbers of the form [Rx_A, Tx_A; Rx_Z, Tx_Z] — Rx_A and Rx_Z specify the azimuth and zenith of the direction of travel of the receiver UE, respectively. Tx_A and Tx_Z specify the azimuth and zenith of the direction of travel of the transmitter UE, respectively. (since R2023b)

Data Types: double

MovingScattererProportion — Proportion of moving scatterers

0.2 (default) | real number in the range [0, 1]

Since R2023b

Proportion of the moving scatterers in the channel, specified as a real number in the range [0, 1]. Setting this property to 0 specifies that none of the scatterers are moving. Setting this property to 1 specifies that every scatterer is moving. The object selects the moving scatterers randomly based on the RandomStream property setting. This property applies only to dual-mobility configurations.

Dependencies

To enable this property, set the MaximumDopplerShift property to a 1-by-2 vector or the UTDirectionOfTravel property to a 2-by-2 matrix.

Data Types: double

MaximumScattererSpeed — Maximum speed of moving scatterers

5 (default) | nonnegative real number

Since R2023b

Maximum speed of the moving scatterers in the channel in m/s, specified as a nonnegative real number. This property applies only to dual-mobility configurations.

Dependencies

To enable this property, set the MaximumDopplerShift property to a 1-by-2 vector or the UTDirectionOfTravel property to a 2-by-2 matrix.

Data Types: double

Channel Control

These properties configure implementation-specific parameters of the channel that are not defined by TR 38.901. For example, you can enable or disable channel filtering, set the data type and the number of samples of the filtered signal, and set control parameters for the path gain generation.

SampleRate — Sample rate of input signal in Hz

30720000 (default) | positive numeric scalar

Sample rate of the input signal in Hz, specified as a positive numeric scalar.

Data Types: double

InitialTime — Time offset of fading process in seconds

0.0 (default) | nonnegative real number

Time offset of fading process in seconds, specified as a nonnegative real number.

Tunable: Yes

Data Types: double

SampleDensity — Number of time samples per half wavelength

64 (default) | Inf | positive real number

Number of time samples per half wavelength, specified as Inf or a positive real number. The SampleDensity and MaximumDopplerShift properties control the coefficient generation sampling rate, Fcg, given by

Fcg = (sum(MaximumDopplerShift) + (2 × (MaximumScattererSpeed/lambda₀))) × 2 × SampleDensity, where lambda₀ is the carrier wavelength.

Setting SampleDensity to Inf assigns Fcg the value of the SampleRate property.

For an example of how sample density affects the channel output and path gains, see Effect of SampleDensity Property in CDL Channel Output.

Data Types: double

RandomStream — Source of random number stream

'mt19937ar with seed' (default) | 'Global stream'

Source of the random number stream to initialize the ray phases and coupling using uniformly distributed random numbers, specified as one of these values:

• 'mt19937ar with seed' — The object uses the mt19937ar algorithm for the random number generation. Calling the reset function resets the filters and reinitializes the random number stream to the value of the Seed property. Specifying this value results in repeatable channel fading.

• 'Global stream' — The object uses the current global random number stream for the random number generation. Calling the reset function resets only the filters.

Dependencies

To enable this property, set the RayCoupling or InitialPhases properties to 'Random' or configure the object with dual-mobility. To configure dual-mobility, set the MaximumDopplerShift property to a 1-by-2 vector or the UTDirectionOfTravel property to a 2-by-2 matrix.

Seed — Initial seed of mt19937ar random number stream

73 (default) | nonnegative numeric scalar

Initial seed of mt19937ar random number stream, specified as a nonnegative numeric scalar.

Dependencies

To enable this property, set RandomStream to 'mt19937ar with seed'. When calling the reset function, the seed reinitializes the mt19937ar random number stream.

Data Types: double

NormalizeChannelOutputs — Normalize channel outputs

true (default) | false

Normalize channel outputs, specified as true or false. When this property is set to true, the channel output signal is divided by the square root of the number of receive antennas. The normalization is by N_R, where N_R is the number of receive antenna elements or the number of antenna subarrays (only when you specify the ReceiveAntennaArray property as a phased.ReplicatedSubarray (Phased Array System Toolbox) or phased.PartitionedArray (Phased Array System Toolbox) phased array object). To determine the value of N_R, check the NumOutputSignals structure field in the output of the info(cdl) object function call.

Note

When you call the swapTransmitAndReceive function to reverse the role of the transmit and receive antennas within the channel, the function also swaps these output structure fields of the info(cdl) function call:

• NumTransmitAntennas and NumReceiveAntennas

• NumInputSignals and NumOutputSignals

Therefore, the normalization is always by N_R.

Data Types: logical

NormalizePathGains — Normalized channel fading process

true (default) | false

Normalized channel fading process, specified as true or false. When this property is set to true, the amplitude of the channel fading process is normalized by the average path gains (also referred to as cluster powers in TR 38.901). This normalization does not include other channel gains, for example, polarization and antenna element directivity. When this property is set to false, the channel fading process is not normalized. The DelayProfile property determines the average path gains, based on TR 38.901 Section 7.7.1, Tables 7.7.1-1 to 7.7.1-5. When you set DelayProfile to 'Custom', you can specify the average path gains with the AveragePathGains property.

Data Types: logical

ChannelFiltering — Fading channel filtering

true (default) | false

Fading channel filtering, specified as true or false. When this property is set to false, these conditions apply:

• The object takes no input signal and returns only the path gains and sample times.

• The SampleDensity property determines when to sample the channel coefficients.

• The NumTimeSamples property controls the duration of the fading process realization at a sampling rate given by the SampleRate property.

For a use case of disabling channel filtering, see the CDL Channel Model Customization with Ray Tracing example.

For an overview of how this property affects the internal architecture of the channel, see Internal Architecture of CDL Channel Model.

Data Types: logical

NumTimeSamples — Number of time samples

30720 (default) | positive integer

Number of time samples, specified as a positive integer. Use this property to set the duration of the fading process realization.

Tunable: Yes

Dependencies

To enable this property, set ChannelFiltering to false.

Data Types: double

OutputDataType — Data type of generated path gains

'double' (default) | 'single'

Data type of generated path gains, specified as 'double' or 'single'.

Dependencies

To enable this property, set ChannelFiltering to false.

Data Types: double

Read-Only Properties

TransmitAndReceiveSwapped — Reversed channel link direction

false (default) | true

This property is read-only.

Reversed channel link direction, returned as one of these values:

• false — The role of the transmit and receive antennas within the channel model corresponds to the original channel link direction. Calling the swapTransmitAndReceive function on the nrCDLChannel object reverses the link direction of the channel and toggles this property value from false to true.

• true — The role of the transmit and receive antennas within the channel model are swapped. Calling the swapTransmitAndReceive function on the nrCDLChannel object restores the original link direction of the channel and toggles this property value from true to false.

Data Types: logical

Usage

Syntax

signalOut = cdl(signalIn)

[signalOut,pathGains] = cdl(signalIn)

[signalOut,pathGains,sampleTimes] = cdl(signalIn)

[pathGains,sampleTimes] = cdl()

Description

signalOut = cdl(signalIn) sends the input signal through a CDL MIMO fading channel and returns the channel-impaired signal.

[signalOut,pathGains] = cdl(signalIn) also returns the MIMO channel path gains of the underlying fading process.

[signalOut,pathGains,sampleTimes] = cdl(signalIn) also returns the sample times of the channel snapshots of pathGains (first-dimension elements).

[pathGains,sampleTimes] = cdl() returns only the path gains and the sample times. The cdl object acts as a source of the path gains and sample times without filtering an input signal. The NumTimeSamples object property specifies the duration of the fading process and the OutputDataType object property specifies the data type of the generated path gains. To use this syntax, you must set the ChannelFiltering object property to false.

Input Arguments

signalIn — Input signal

complex scalar | column vector | N_S-by-N_T matrix

Input signal, specified as a complex scalar, column vector, or N_S-by-N_T matrix, where:

• N_S is the number of samples.

• N_T is the number of transmit antenna elements or the number of antenna subarrays (only when you specify the TransmitAntennaArray property as a phased.ReplicatedSubarray (Phased Array System Toolbox) or phased.PartitionedArray (Phased Array System Toolbox) phased array object). To determine the value of N_T, check the NumInputSignals structure field in the output of the info(cdl) object function call.

Data Types: single | double
Complex Number Support: Yes

Output Arguments

signalOut — Output signal

complex scalar | vector | N_S-by-N_R matrix

Output signal, returned as a complex scalar, vector, or N_S-by-N_R matrix, where:

• N_S is the number of samples.

• N_R is the number of receive antenna elements or the number of antenna subarrays (only when you specify the ReceiveAntennaArray property as a phased.ReplicatedSubarray (Phased Array System Toolbox) or phased.PartitionedArray (Phased Array System Toolbox) phased array object). To determine the value of N_R, check the NumOutputSignals structure field in the output of the info(cdl) object function call.

The output signal data type is of the same precision as the input signal data type.

Data Types: single | double
Complex Number Support: Yes

pathGains — MIMO channel path gains of fading process

N_CS-by-N_P-by-N_T-by-N_R complex array

MIMO channel path gains of the fading process, returned as an N_CS-by-N_P-by-N_T-by-N_R complex array, where:

• N_CS is the number of channel snapshots, controlled by the SampleDensity property of cdl.

• N_P is the number of paths, specified by the size of the PathDelays property of cdl.

• N_T is the number of transmit antenna elements or the number of antenna subarrays (only when you specify the TransmitAntennaArray property as a phased.ReplicatedSubarray (Phased Array System Toolbox) or phased.PartitionedArray (Phased Array System Toolbox) phased array object). To determine the value of N_T, check the NumInputSignals structure field in the output of the info(cdl) object function call.

• N_R is the number of receive antenna elements or the number of antenna subarrays (only when you specify the ReceiveAntennaArray property as a phased.ReplicatedSubarray (Phased Array System Toolbox) or phased.PartitionedArray (Phased Array System Toolbox) phased array object). To determine the value of N_R, check the NumOutputSignals structure field in the output of the info(cdl) object function call.

The path gains data type is of the same precision as the input signal data type.

Data Types: single | double
Complex Number Support: Yes

sampleTimes — Sample times of channel snapshots

N_CS-by-1 column vector

Sample times of channel snapshots, returned as an N_CS-by-1 column vector, where N_CS is the number of channel snapshots controlled by the SampleDensity property.

Data Types: double

Object Functions

To use an object function, specify the System object as the first input argument. For example, to release system resources of a System object named obj, use this syntax:

release(obj)

Specific to nrCDLChannel

info	Characteristic information of link-level MIMO channel
getPathFilters	Get path filter impulse response for link-level MIMO channel
displayChannel	Visualize and explore CDL channel model characteristics
swapTransmitAndReceive	Reverse link direction in CDL channel model

Common to All System Objects

step	Run System object algorithm
clone	Create duplicate System object
isLocked	Determine if System object is in use
release	Release resources and allow changes to System object property values and input characteristics
reset	Reset internal states of System object

Examples

Transmission Over Channel Model with Delay Profile CDL-D

Transmit a waveform through a clustered delay line (CDL) channel model with delay profile CDL-D from TR 38.901 Section 7.7.1.

Define the channel configuration structure using an nrCDLChannel System object. Use delay profile CDL-D, a delay spread of 10 ns, and UE velocity of 15 km/h.

v = 15.0;                    % UE velocity in km/h
fc = 4e9;                    % carrier frequency in Hz
c = physconst('lightspeed'); % speed of light in m/s
fd = (v*1000/3600)/c*fc;     % UE max Doppler frequency in Hz
 
cdl = nrCDLChannel;
cdl.DelayProfile = 'CDL-D';
cdl.DelaySpread = 10e-9;
cdl.CarrierFrequency = fc;
cdl.MaximumDopplerShift = fd;

Configure the transmit array layout as a vector of the form [M N P Mg Ng] = [2 4 2 1 2], representing two panels (Mg = 1, Ng = 2) with a 2-by-4 antenna array (M = 2, N = 4) and two polarization angles (P = 2). Configure the receive antenna array as a vector of the form [M N P Mg Ng] = [1 1 2 1 1], representing a single pair of cross-polarized co-located antennas.

cdl.TransmitAntennaArray.Size = [2 4 2 1 2];
cdl.ReceiveAntennaArray.Size = [1 1 2 1 1];

Set the distance between the transmit antenna elements to half wavelength. Specify the distance between the antenna panel centers to evenly distribute the antenna elements of all panels and avoid panel overlapping.

cdl.TransmitAntennaArray.ElementSpacing(1:2) = 0.5;
cdl.TransmitAntennaArray.ElementSpacing(3:4) = cdl.TransmitAntennaArray.ElementSpacing(1:2).*(cdl.TransmitAntennaArray.Size(1:2));

Verify the configuration by displaying the channel.

displayChannel(cdl,'LinkEnd','Tx')

displayChannel(cdl,'LinkEnd','Rx')

Create a random waveform of one subframe duration with eight antennas.

SR = 15.36e6;
T = SR * 1e-3;
cdl.SampleRate = SR;
cdlinfo = info(cdl);
Nt = cdlinfo.NumInputSignals;
 
txWaveform = complex(randn(T,Nt),randn(T,Nt));

Transmit the input waveform through the channel.

rxWaveform = cdl(txWaveform);

Effect of SampleDensity Property in CDL Channel Output

Plot channel output and path gain snapshots for various sample density values while using an nrCDLChannel System object.

Configure a channel with delay profile CDL-B from TR 38.901 Section 7.7.1. Set the maximum Doppler shift to 300 Hz and the channel sampling rate to 10 kHz.

cdl = nrCDLChannel;
cdl.DelayProfile = 'CDL-B';
cdl.MaximumDopplerShift = 300.0;
cdl.SampleRate = 10e3;
cdl.Seed = 19;

Configure the transmit and receive antenna arrays for single-input/single-output (SISO) operation.

cdl.TransmitAntennaArray.Size = [1 1 1 1 1];
cdl.ReceiveAntennaArray.Size = [1 1 1 1 1];

Create an input waveform with a length of 40 samples.

T = 40; 
in = ones(T,1);

Plot the step response of the channel (displayed as lines) and the corresponding path gain snapshots (displayed circles) for various values of the SampleDensity property. The sample density property controls how often the channel snapshots are taken relative to the Doppler frequency.

• When SampleDensity is set to Inf, a channel snapshot is taken for every input sample.

• When SampleDensity is set to a scalar S, a channel snapshot is taken at a rate of ${\mathit{F}}_{\mathrm{CS}}=2\mathit{S}\times \mathit{MaximumDopplerShift}$.

The nrCDLChannel object applies the channel snapshots to the input waveform by means of zero-order hold interpolation. The object takes an extra snapshot beyond the end of the input. Some of the final output samples use this extra value to minimize the interpolation error. The channel output contains a transient (and a delay) due to the filters that implement the path delays.

s = [Inf 5 2]; % sample densities

legends = {};
figure; hold on;
SR = cdl.SampleRate;
for i = 1:length(s)
    
    % call channel with chosen sample density
    release(cdl); cdl.SampleDensity = s(i);
    [out,pathgains,sampletimes] = cdl(in);
    chInfo = info(cdl); tau = chInfo.ChannelFilterDelay;
    
    % plot channel output against time
    t = cdl.InitialTime + ((0:(T-1)) - tau).' / SR;
    h = plot(t,abs(out),'o-'); 
    h.MarkerSize = 2; 
    h.LineWidth = 1.5;
    desc = ['Sample Density = ' num2str(s(i))];
    legends = [legends ['Output, ' desc]];
    disp([desc ', Ncs = ' num2str(length(sampletimes))]);
    
    % plot path gains against sample times
    h2 = plot(sampletimes-tau/SR,abs(sum(pathgains,2)),'o');
    h2.Color = h.Color; 
    h2.MarkerFaceColor = h.Color;
    legends = [legends ['Path Gains, ' desc]];    
end

Sample Density = Inf, Ncs = 40
Sample Density = 5, Ncs = 13
Sample Density = 2, Ncs = 6

xlabel('Time (s)');
title('Channel Output and Path Gains vs. Sample Density');
ylabel('Channel Magnitude');
legend(legends,'Location','NorthWest');

Orient Transmit and Receive Antennas Using LOS Path Angles

Create a CDL channel model. Then specify a light-of-sight (LOS) channel.

cdl = nrCDLChannel; 
cdl.DelayProfile = 'CDL-D'; % LOS channel
cdl.TransmitAntennaArray.Element = '38.901';
cdl.ReceiveAntennaArray.Element = '38.901';

Retrieve channel characteristic information. Orient the transmit and receive antenna arrays to point at each other by using the LOS path angles returned in the characteristic information.

cdlInfo = cdl.info;
cdl.TransmitArrayOrientation = [cdlInfo.AnglesAoD(1) cdlInfo.AnglesZoD(1)-90 0]';
cdl.ReceiveArrayOrientation = [cdlInfo.AnglesAoA(1) cdlInfo.AnglesZoA(1)-90 0]';

Visualize the channel characteristics at the transmitter end.

cdl.displayChannel('LinkEnd','Tx');
view(0,90)

Visualize the channel characteristics at the receiver end. The strongest path (LOS) passes through the maximum of the antenna element radiation pattern, which confirms that the antennas point at each other.

cdl.displayChannel('LinkEnd','Rx')
view(0,90)

Configure CDL Channel Antenna Using Phased Array

Create a CDL channel model. Then specify a phased array for the transmit antenna array.

cdl = nrCDLChannel;
cdl.TransmitAntennaArray = phased.URA;

Specify a cross-dipole transmit antenna array element to generate circularly polarized fields.

cdl.TransmitAntennaArray.Element = phased.CrossedDipoleAntennaElement;

Set the broadside direction of the array toward the positive y-axis. Add a 30 degree downtilt.

cdl.TransmitAntennaArray.ArrayNormal = 'y';
cdl.TransmitArrayOrientation = [0; 30; 0];

Set the antenna element spacing to half wavelength.

lambda = physconst('lightspeed')/cdl.CarrierFrequency;
cdl.TransmitAntennaArray.ElementSpacing = [lambda/2 lambda/2];

Visualize the channel characteristics at the transmitter end.

cdl.displayChannel('LinkEnd','Tx');

Algorithms

Internal Architecture of CDL Channel Model

The object properties configure the CDL channel filtering and channel coefficients generation.

CDL Channel Filtering

To enable or disable CDL channel filtering, use the ChannelFiltering property.

• CDL Channel Filtering Enabled — When you set ChannelFiltering to true, the object accepts an input signal and returns the channel-impaired signal, path gains of the fading process, and sample times of the channel snapshots.

  

• CDL Channel Filtering Disabled — When you set ChannelFiltering to false, the object does not accept an input signal and returns only the path gains and sample times. In this case, use the OutputDataType and NumTimeSamples properties to set the path gains data type and the duration of the fading process realization, respectively.

  

Channel Coefficients Generation

To configure TR 38.901-specific parameters:

• Set the delay profile, DelayProfile, then configure delay-profile-specific parameters. Depending on the delay profile, use the properties listed in the Predefined Delay Profile or Custom Delay Profile sections.

• Configure the channel geometry by using the properties listed in the Antenna Array section.

• Configure the UE mobility by using the properties listed in the Mobility section.

To configure non-TR 38.901-specific implementation details of the coefficients generation, use the properties listed in the Channel Control section.

References

[1] 3GPP TR 38.901. “Study on channel model for frequencies from 0.5 to 100 GHz.” 3rd Generation Partnership Project; Technical Specification Group Radio Access Network.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

See System Objects in MATLAB Code Generation (MATLAB Coder).

Version History

Introduced in R2018b

R2023b: Customize CDL channel model from predefined delay profile

You can create a channel model with a custom delay profile that is initialized with the parameters of one of the predefined delay profiles, as defined in TR 38.901 Tables 7.7.1-1 to 7.7.1-5. For more information on the corresponding object creation syntaxes, see the Description section.

R2023b: Support for dual-mobility

You can use the MaximumDopplerShift and UTDirectionOfTravel object properties to configure V2X fading channels for the transmitter and receiver. To control clutter mobility, use the MovingScattererProportion and MaximumScattererSpeed object properties.

R2021a: Orientation field of antenna array properties will be removed

• The Orientation field of the TransmitAntennaArray property will be removed in a future release. Use the TransmitArrayOrientation property instead.

• The Orientation field of the ReceiveAntennaArray property will be removed in a future release. Use the ReceiveArrayOrientation property instead.