nrPRSIndices

Generate PRS resource element indices

Since R2021a

Syntax

ind = nrPRSIndices(carrier,prs)

ind = nrPRSIndices(carrier,prs,Name,Value)

Description

ind = nrPRSIndices(carrier,prs) generates positioning reference signal (PRS) resource element (RE) indices ind, as defined in TS 38.211 Section 7.4.1.7.3 [1], for carrier configuration carrier and PRS configuration prs. The function also handles the conditions related to the mapping of PRS resources to slots, as defined in TS 38.211 Section 7.4.1.7.4.

ind = nrPRSIndices(carrier,prs,Name,Value) specifies options by using one or more name-value arguments. For example, 'IndexBase','0based' specifies the RE indexing base as 0.

Examples

Generate PRS Indices for Multiple Resources in Resource Set

Create a default carrier configuration object.

carrier = nrCarrierConfig;

Create a default PRS configuration object.

prs = nrPRSConfig;

Set properties that are common to all PRS resources in a resource set.

prs.PRSResourceSetPeriod = [20 0];
prs.PRSResourceRepetition = 4;
prs.PRSResourceTimeGap = 2;
prs.MutingPattern1 = [1 0];
prs.MutingBitRepetition = 2;
prs.MutingPattern2 = [1 0 1 0];
prs.NumRB = 32;
prs.RBOffset = 10;
prs.CombSize = 4; 

Set properties that are unique to each PRS resource in a resource set. You can specify these properties as a scalar or vector. If you specify a scalar, the object applies that value to all of the PRS resources in a PRS resource set. If you specify a vector, the object applies the vector element values to the corresponding PRS resource. The length of this vector must be equal to the number of PRS resources to be configured in a PRS resource set.

prs.PRSResourceOffset = [0 10];
prs.NumPRSSymbols = [6 4];
prs.SymbolStart = [0 1];
prs.REOffset = 0;
prs.NPRSID = [10 50];

Generate 0-based PRS RE indices with subscript RE indexing form.

ind = nrPRSIndices(carrier,prs,'IndexStyle','subscript','IndexBase','0based')

ind = 576x3 uint32 matrix

   120     0     0
   124     0     0
   128     0     0
   132     0     0
   136     0     0
   140     0     0
   144     0     0
   148     0     0
   152     0     0
   156     0     0
      ⋮

Generate PRS Symbols and Indices for Two Resources

Create a default carrier configuration object.

carrier = nrCarrierConfig;

Create a default PRS configuration object.

prs = nrPRSConfig;

Set properties related to the PRS slot configuration.

prs.PRSResourceSetPeriod = [8 0]; % Resource set periodicity of 8 slots and resource set slot offset of 0 slots
prs.PRSResourceOffset = [0 4];    % Configure two PRS resources with slot offsets 0 and 4 relative to resource set offset
prs.PRSResourceRepetition = 2;    % Repeat each PRS resource twice
prs.PRSResourceTimeGap = 1;       % Configure two PRS resource repetition indices with no time gap

Set properties related to the PRS muting configuration.

prs.MutingPattern1 = [1 1];       % Transmit all PRS resource set instances
prs.MutingBitRepetition = 1;      % One instance of a PRS resource set corresponding to a single element of MutingPattern1 binary vector
prs.MutingPattern2 = [1 0];       % Mute second repetition index of all the PRS resources within an active instance of a PRS resource set

Set properties related to the PRS time-domain allocation.

prs.NumPRSSymbols = [6 12];
prs.SymbolStart = [6 0];

Set properties related to the PRS frequency-domain allocation.

prs.NumRB = 40;
prs.RBOffset = 4;
prs.CombSize = 4;
prs.REOffset = [1 3];
prs.NPRSID = 5;       % Set PRS sequence identity

Get the number of orthogonal frequency division multiplexing (OFDM) symbols per slot.

numSymPerSlot = carrier.SymbolsPerSlot;

Set the number of slots to 20.

numSlots = 20;

Map the resource elements (RE) for both of the PRS resources on the carrier resource grid.

grid = complex(zeros(carrier.NSizeGrid*12,carrier.SymbolsPerSlot*numSlots));
for slotIdx = 0:numSlots-1
    carrier.NSlot = slotIdx;
    indCell = nrPRSIndices(carrier,prs,'OutputResourceFormat','cell');
    symCell = nrPRS(carrier,prs,'OutputResourceFormat','cell');
    slotGrid = nrResourceGrid(carrier);
    slotGrid(indCell{1}) = 70*symCell{1};                              % Resource element mapping of PRS resource 1 with some scaling for plotting purpose
    slotGrid(indCell{2}) = 250*symCell{2};                             % Resource element mapping of PRS resource 2 with some scaling for plotting purpose
    grid(:,(1:numSymPerSlot)+numSymPerSlot*slotIdx) = slotGrid;
end
figure
image(abs(grid));
axis xy;
L = line(ones(2),ones(2),'LineWidth',8);               % Generate lines
set(L,{'color'},{[0.18 0.51 0.98]; [0.96 0.95 0.11]}); % Set the colors
legend('PRS Resource 1','PRS Resource 2');             % Create legend
title('PRS Resource Elements');
xlabel('OFDM Symbols');
ylabel('Subcarriers');

Input Arguments

carrier — Carrier configuration parameters

nrCarrierConfig object

Carrier configuration parameters for a specific OFDM numerology, specified as an nrCarrierConfig object. This function uses only these nrCarrierConfig object properties.

SubcarrierSpacing — Subcarrier spacing in kHz

15 (default) | 30 | 60 | 120 | 240 | 480 | 960

Subcarrier spacing in kHz, for all channels and reference signals of the carrier, specified as 15, 30, 60, 120, 240, 480, or 960.

Data Types: double

CyclicPrefix — Cyclic prefix length

'normal' (default) | 'extended'

Cyclic prefix length, specified as one of these options.

• 'normal' — Use this value to specify normal cyclic prefix. This option corresponds to 14 OFDM symbols in a slot.

• 'extended' — Use this value to specify extended cyclic prefix. This option corresponds to 12 OFDM symbols in a slot. For the numerologies specified in TS 38.211 Section 4.2, extended cyclic prefix length applies for only 60 kHz subcarrier spacing.

Data Types: char | string

NSizeGrid — Number of RBs in carrier resource grid

52 (default) | integer from 1 to 275

Number of RBs in the carrier resource grid, specified as an integer from 1 to 275. The default value of 52 corresponds to the maximum number of RBs of a 10 MHz carrier with 15 kHz SCS.

Data Types: double

NStartGrid — Start of carrier resource grid relative to CRB 0

0 (default) | integer from 0 to 2199

Start of carrier resource grid relative to CRB 0, specified as an integer from 0 to 2199. This property is the higher-layer parameter offsetToCarrier.

Data Types: double

NSlot — Slot number

0 (default) | nonnegative integer

Slot number, specified as a nonnegative integer. You can set NSlot to a value larger than the number of slots per frame. For example, you can set this value using transmission loop counters in a MATLAB^® simulation. In this case, you may have to ensure that the property value is modulo the number of slots per frame in a calling code.

Data Types: double

NFrame — System frame number

0 (default) | nonnegative integer

System frame number, specified as a nonnegative integer. You can set NFrame to a value larger than the maximum frame number 1023. For example, you can set this value using transmission loop counters in a MATLAB simulation. In this case, you may have to ensure that the property value is modulo 1024 in a calling code.

Data Types: double

prs — PRS configuration parameters

nrPRSConfig object

PRS configuration parameters, specified as an nrPRSConfig object. This function uses only these nrPRSConfig object properties.

PRSResourceSetPeriod — PRS resource set slot periodicity and slot offset

'on' (default) | 'off' | two-element vector

PRS resource set slot periodicity and slot offset, specified as one of these options.

• 'on' — All of the PRS resources are present in the operating slot.

• 'off' — All of the PRS resources are absent in the operating slot.

• Two-element vector of the form [TPRSPeriod, TPRSOffset] — TPRSPeriod is the resource set slot periodicity. The nominal value of TPRSPeriod must equal 2^μ multiplied by one of the values in the set {4, 5, 8, 10, 16, 20, 32, 40, 64, 80, 160, 320, 640, 1280, 2560, 5120, 10,240}, where μ is the subcarrier spacing configuration with a value of 0, 1, 2, or 3. TPRSOffset is the resource set slot offset and must equal a value in the range [0, TPRSPeriod – 1].

Data Types: double | string | char

PRSResourceOffset — Slot offset of each PRS resource

0 (default) | scalar in the range [0, 511] | vector of integers in the range [0, 511]

Slot offset of each PRS resource (0-based) provided by the higher layer parameter dl-PRS-ResourceSlotOffset-r16, specified as a scalar in the range [0, 511] or a vector of integers in the range [0, 511]. This property represents the starting slot offset of a PRS resource relative to the PRS resource set offset (TPRSOffset).

Configure this property for each resource in a resource set separately based on one of these options.

• When a single resource is present, specify this property as a scalar.

• When multiple resources are present, specify this property as a scalar or vector. If you specify a scalar, the object applies that value to all of the PRS resources in a PRS resource set. If you specify a vector, the object applies the vector element values to the corresponding PRS resource. The length of this vector must be equal to the number of PRS resources to be configured in a PRS resource set.

Dependencies

To enable this property, set the PRSResourceSetPeriod property to a two-element vector of the form [TPRSPeriod, TPRSOffset].

Data Types: double

PRSResourceRepetition — PRS resource repetition factor

1 (default) | 2 | 4 | 6 | 8 | 16 | 32

PRS resource repetition factor provided by the higher layer parameter dl-PRS-ResourceRepetitionFactor-r16, specified as 1, 2, 4, 6, 8, 16, or 32. This property value is the same for all of the PRS resources in a PRS resource set.

Dependencies

To enable this property, set the PRSResourceSetPeriod property to a two-element vector of the form [TPRSPeriod, TPRSOffset].

Data Types: double

PRSResourceTimeGap — Slot offset between two consecutive repeated instances of a PRS resource

1 (default) | 2 | 4 | 8 | 16 | 32

Slot offset between two consecutive repeated instances of a PRS resource, specified as 1, 2, 4, 8, 16, or 32. The property represents the offset in terms of the number of slots between two repeated instances of a PRS resource. This property value is same the for all of the PRS resources in a PRS resource set. This property is the higher layer parameter dl-PRS-ResourceTimeGap-r16.

Dependencies

To enable this property, set the PRSResourceSetPeriod property to a two-element vector of the form [TPRSPeriod, TPRSOffset] and the PRSResourceRepetition property to a value greater than 1.

Data Types: double

MutingPattern1 — Muting bit pattern option-1

[] (default) | binary-valued vector of length 2, 4, 6, 8, 16, or 32

Muting bit pattern option-1, specified as [] or a binary-valued vector of length 2, 4, 6, 8, 16, or 32.

• If the higher layer parameter mutingOption1-r16 is configured, set this property to a binary-valued vector of length 2, 4, 6, 8, 16, or 32. Each element in the vector corresponds to a number of consecutive instances of a PRS resource set based on the MutingBitRepetition property. The vector element also indicates whether all of the PRS resources within the PRS resource set instances are transmitted (binary 1) or muted (binary 0).

• If the higher layer parameter mutingOption1-r16 is not configured, set this property to []. To disable the muting bit pattern option-1, set this property to [].

Dependencies

To enable this property, set the PRSResourceSetPeriod property to a two-element vector of the form [TPRSPeriod, TPRSOffset].

Data Types: double

MutingBitRepetition — Muting bit repetition factor

1 (default) | 2 | 4 | 8

Muting bit repetition factor provided by the higher layer parameter dl-PRS-MutingBitRepetitionFactor-r16, specified as 1, 2, 4, or 8. This property indicates the number of consecutive instances of the PRS resource set, N, corresponding to each element of the MutingPattern1 property. The first element in MutingPattern1 corresponds to the first N instances of a PRS resource set, the second element corresponds to the next N instances of a PRS resource set, and so on.

Dependencies

To enable this property, set the PRSResourceSetPeriod property to a two-element vector of the form [TPRSPeriod, TPRSOffset] and the MutingPattern1 property to a value other than [].

Data Types: double

MutingPattern2 — Muting bit pattern option-2

[] (default) | binary-valued vector of length 1, 2, 4, 6, 8, 16, or 32

Muting bit pattern option-2, specified as [] or a binary-valued vector of length 1, 2, 4, 6, 8, 16, or 32.

• If the higher layer parameter mutingOption2-r16 is configured, set this property to a binary-valued vector of length 1, 2, 4, 6, 8, 16, or 32. Each element in the vector relates to the corresponding repetition index. Each element in the vector corresponds to a single repetition index of each PRS resource in an active instance of a PRS resource set. The vector element also indicates whether the repetition index for all of the PRS resources is transmitted (binary 1) or muted (binary 0).

• If the higher layer parameter mutingOption2-r16 is not configured, set this property to []. To disable the muting bit pattern option-2, set this property to [].

Dependencies

To enable this property, set the PRSResourceSetPeriod property to a two-element vector of the form [TPRSPeriod, TPRSOffset].

Data Types: double

NumPRSSymbols — Number of consecutive OFDM symbols allocated for each PRS resource

12 (default) | scalar in the range [0, 12] | vector of integers in the range [0, 12]

Number of consecutive OFDM symbols allocated for each PRS resource, specified as a scalar in the range [0, 12] or a vector of integers in the range [0, 12].

Configure this property for each resource in a resource set separately based on one of these options.

• When a single resource is present, specify this property as a scalar.

• When multiple resources are present, specify this property as a scalar or vector. If you specify a scalar, the object applies that value to all of the PRS resources in a PRS resource set. If you specify a vector, the object applies the vector element values to the corresponding PRS resource. The length of this vector must be equal to the number of PRS resources to be configured in a PRS resource set.

This property is the higher layer parameter dl-PRS-NumSymbols-r16, and the nominal value of this property must be 2, 4, 6, or 12. To indicate no PRS resource allocation, set this property to 0.

Data Types: double

SymbolStart — Starting OFDM symbol of each PRS resource in slot

0 (default) | scalar in the range [0, 13] | vector of integers in the range [0, 13]

Starting OFDM symbol of each PRS resource in a slot (0-based), specified as a scalar in the range [0, 13] or a vector of integers in the range [0, 13].

Configure this property for each resource in a resource set separately based on one of these options.

• When a single resource is present, specify this property as a scalar.

• When multiple resources are present, specify this property as a scalar or vector. If you specify a scalar, the object applies that value to all of the PRS resources in a PRS resource set. If you specify a vector, the object applies the vector element values to the corresponding PRS resource. The length of this vector must be equal to the number of PRS resources to be configured in a PRS resource set.

This property is the higher layer parameter dl-PRS-ResourceSymbolOffset-r16, and the nominal value of this property must be in the range [0, 12].

Data Types: double

NumRB — Number of PRBs allocated for all PRS resources

52 (default) | scalar in the range [0, 275]

Number of PRBs allocated for all PRS resources in a resource set, specified as a scalar in the range [0, 275]. This property is the higher layer parameter dl-PRS-ResourceBandwidth-r16, and the nominal value of this property must be in the range [24, 272] with a granularity of 4 PRBs. To indicate no PRS resource allocation, set this property to 0.

Data Types: double

RBOffset — Starting PRB index of all PRS resources relative to carrier resource grid

0 (default) | scalar in the range [0, 274]

Starting PRB index of all PRS resources relative to the carrier resource grid, specified as a scalar in the range [0, 274].

Data Types: double

CombSize — Comb size of all PRS resources

2 (default) | 4 | 6 | 12

Comb size of all PRS resources in a resource set, specified as 2, 4, 6, or 12. The comb size represents the resource element spacing in each OFDM symbol. This property is the higher layer parameter dl-PRS-CombSizeN-r16. The value 2 specifies for the object to allocate every 2nd RE in the PRB for PRS, the value 4 specifies for the object to allocate every 4th RE in the PRB for PRS, and so on.

Data Types: double

REOffset — Starting RE offset in first PRS OFDM symbol of each PRS resource

0 (default) | scalar in the range [0, (CombSize–1)] | vector of integers in the range [0, (CombSize–1)]

Starting RE offset in the first PRS OFDM symbol of each PRS resource, specified as a scalar in the range [0, (CombSize–1)] or a vector of integers in the range [0, (CombSize–1)]. The relative RE offsets of the next PRS OFDM symbols are defined relative to the REOffset value, as described in TS 38.211 Table 7.4.1.7.3-1.

Configure this property for each resource in a resource set separately based on one of these options.

• When a single resource is present, specify this property as a scalar.

• When multiple resources are present, specify this property as a scalar or vector. If you specify a scalar, the object applies that value to all of the PRS resources in a PRS resource set. If you specify a vector, the object applies the vector element values to the corresponding PRS resource. The length of this vector must be equal to the number of PRS resources to be configured in a PRS resource set.

This property is the higher layer parameter dl-PRS-ReOffset-r16.

Data Types: double

Note

The maximum vector length of these five properties of nrPRSConfig object specifies the number of configured PRS resources.

• PRSResourceOffset

• NumPRSSymbols

• SymbolStart

• REOffset

• NPRSID

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: 'IndexStyle','subscript' specifies the RE indexing style of the output indices as 'subscript'.

IndexStyle — RE indexing form

'index' (default) | 'subscript'

RE indexing form, specified as one of these values:

• 'index' — The indices are in linear index form.

• 'subscript' — The indices are in [subcarrier, symbol, antenna] subscript row form.

Data Types: char | string

IndexBase — RE indexing base

'1based' (default) | '0based'

RE indexing base, specified as one of these values:

• '1based' — The index counting starts from 1.

• '0based' — The index counting starts from 0.

Data Types: char | string

OutputResourceFormat — Output format of PRS resource element indices

'concatenated' (default) | 'cell'

Output format of PRS resource element indices, specified as one of these values:

• 'concatenated' — The output ind is a single column vector containing all PRS resource element indices concatenated.

• 'cell' — The output ind is a cell array where each cell corresponds to a single PRS resource.

Data Types: char | string

Output Arguments

ind — PRS RE indices

column vector | M-by-3 matrix | cell array of column vectors | cell array of matrices

PRS RE indices, returned as one of these values.

• Column vector — The function returns the indices output in this format when you set the IndexStyle name-value argument to 'index'.

• M-by-3 matrix — The function returns the indices output in this format when you set the IndexStyle name-value argument to 'subscript'. The matrix rows correspond to the [subcarrier, symbol, antenna] subscripts based on the number of subcarriers, OFDM symbols, and number of antennas, respectively.

• Cell array of column vectors — The function returns the indices output in this format when you set the IndexStyle name-value argument to 'index' and the OutputResourceFormat name-value argument to 'cell'.

• Cell array of matrices — The function returns the indices output in this format when IndexStyle is set to 'subscript' and the OutputResourceFormat name-value argument to 'cell'. The number of rows in each cell varies based on the PRS resource configurations in a PRS resource set.

Depending on the value of IndexBase, the function returns either 1-based or 0-based indices.

Data Types: uint32

References

[1] 3GPP TS 38.211. “NR; Physical channels and modulation (Release 16).” 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:

The 'OutputResourceFormat' name-value argument must be compile-time constant for code generation. For example, when you call the function with 'OutputResourceFormat','concatenated', include {coder.Constant('OutputResourceFormat'),coder.Constant('concatenated')} in the -args value of the codegen function. For more information, see the coder.Constant (MATLAB Coder) class.

Version History

Introduced in R2021a

R2023a: C/C++ code generation updates

For C/C++ code generation, the limitation to specify 'IndexStyle' or 'IndexBase' name-value arguments as compile-time constants has been removed.