nrCDLChannel

Send signal through CDL channel model

Description

The nrCDLChannel System object™ sends an input signal through a clustered delay line (CDL) multi-input multi-output (MIMO) link-level fading channel to obtain the channel-impaired signal. The object implements the following 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

To send a signal through 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)

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 pairs. Enclose the property name inside quotes, followed by the specified value. Unspecified properties take default values.

Example: cdl = nrCDLChannel('DelayProfile','CDL-D','DelaySpread',2e-6) creates the channel object with CDL-D delay profile and 2 microseconds delay spread.

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.

Configurable Channel Properties

DelayProfile — CDL delay profile

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

CDL delay profile, specified as 'CDL-A', 'CDL-B', 'CDL-C', 'CDL-D', 'CDL-E', or 'Custom'. See TR 38.901 Section 7.7.1, Tables 7.7.1-1 to 7.7.1-5.

When you set this property to 'Custom', configure the delay profile using properties PathDelays, AveragePathGains, AnglesAoA, AnglesAoD, AnglesZoA, AnglesZoD, HasLOSCluster, KFactorFirstCluster, AngleSpreads, XPR, and NumStrongestClusters.

Data Types: char | string

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

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 profile.

Data Types: logical

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

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, as described in TR 38.901 Section 7.7.5.1 ($${\mu }_{\Phi ,\text{desired}}$$).

Dependencies

To enable this property, set AngleScaling to true.

Data Types: double

XPR — Cross-polarization power ratio in dB

10.0 (default) | numeric scalar

Cross-polarization power ratio in dB, specified as a numeric scalar. 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.

Dependencies

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

Data Types: double

DelaySpread — Desired RMS delay spread in seconds

30e-9 (default) | numeric scalar

Desired RMS delay spread in seconds, specified as a numeric scalar. 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.

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 profile.

Data Types: double

CarrierFrequency — Carrier frequency in Hz

4e9 (default) | numeric scalar

Carrier frequency in Hz, specified as a numeric scalar.

Data Types: double

MaximumDopplerShift — Maximum Doppler shift in Hz

5 (default) | nonnegative numeric scalar

Maximum Doppler shift in Hz, specified as a nonnegative numeric scalar. 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) | two-element column vector

User terminal (or user equipment) direction of travel in degrees, specified as a two-element column vector. The vector elements specify the azimuth and the zenith components [azimuth; zenith].

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 path powers.

Dependencies

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

Data Types: double

KFactor — Desired K-factor for scaling in dB

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

SampleRate — Sample rate of input signal in Hz

30.72e6 (default) | positive numeric scalar

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

Data Types: double

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 2 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 6 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.
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 superseded 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 towards 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 2 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 6 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.
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 superseded 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 towards each other, see Orient Transmit and Receive Antennas Using LOS Path Angles.

Data Types: double

SampleDensity — Number of time samples per half wavelength

64 (default) | Inf | numeric scalar

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

Fcg = MaximumDopplerShift × 2 × SampleDensity.

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 Plot Channel Transmission Properties with SISO and Delay Profile CDL-B.

Data Types: double

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

InitialTime — Time offset of fading process in seconds

0.0 (default) | numeric scalar

Time offset of fading process in seconds, specified as a numeric scalar.

Tunable: Yes

Data Types: double

NumStrongestClusters — Number of strongest clusters to split into subclusters

0 (default) | numeric scalar

Number of strongest clusters to split into subclusters, specified as a numeric scalar. 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 scalar

Cluster delay spread in seconds, specified as a nonnegative scalar. 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

RandomStream — Source of random number stream

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

Source of random number stream, specified as one of the following:

• 'mt19937ar with seed' — The object uses the mt19937ar algorithm for normally distributed random number generation. Calling the reset function resets the filters and reinitializes the random number stream to the value of the Seed property.

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

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

ChannelFiltering — Fading channel filtering

true (default) | false

Fading channel filtering, specified as true or false. When this property is set to false, the following 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.

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

NormalizeChannelOutputs — Normalize channel outputs

true (default) | false

Normalize channel outputs, specified as true or false. When this property is set to true, the channel outputs are normalized. 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

Hence the normalization is always by N_R.

Dependencies

To enable this property, set ChannelFiltering to true.

Data Types: logical

Nonconfigurable Channel 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. In this case, the NumTimeSamples property determines the duration of the fading process. The object acts as a source of the path gains and sample times without filtering an input signal. To use this syntax, you must set the ChannelFiltering property of cdl 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	Get characteristic information about link-level MIMO fading channel
getPathFilters	Get path filter impulse response for link-level MIMO fading 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 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 as a vector of the form [M N P Mg Ng] = [2 2 2 1 1], representing 1 panel (Mg=1, Ng=1) with a 2-by-2 antenna array (M=2, N=2) 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 2 2 1 1];
cdl.ReceiveAntennaArray.Size = [1 1 2 1 1];

Create a random waveform of 1 subframe duration with 8 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);

Plot Channel Transmission Properties with SISO and Delay Profile CDL-B

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');

Compatibility Considerations

Orientation field of antenna array properties will be removed

Warns starting in R2021a

• 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.

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).