nrPDSCHDMRSIndices

Generate PDSCH DM-RS indices

Syntax

ind = nrPDSCHDMRSIndices(carrier,pdsch)

ind = nrPDSCHDMRSIndices(carrier,pdsch,Name,Value)

Description

ind = nrPDSCHDMRSIndices(carrier,pdsch) returns a matrix containing demodulation reference signal (DM-RS) resource element (RE) indices of a physical downlink shared channel (PDSCH), as defined in TS 38.211 Section 7.4.1.1.2 [1]. carrier specifies the carrier configuration parameters for a specific OFDM numerology. pdsch specifies the PDSCH configuration parameters. The returned indices are 1-based using linear indexing form.

ind = nrPDSCHDMRSIndices(carrier,pdsch,Name,Value) specifies output formatting options using one or more name-value pair arguments. Unspecified options take default values.

Examples

Generate PDSCH DM-RS Symbols and Indices

Create a carrier configuration object specifying the slot number as 10.

carrier = nrCarrierConfig('NSlot',10);

Create a physical downlink shared channel (PDSCH) configuration object, pdsch, with physical resource blocks (PRBs) allocated from 0 to 30.

pdsch = nrPDSCHConfig;
pdsch.PRBSet = 0:30;

Create a PDSCH demodulation reference signal (DM-RS) object, dmrs, with specified properties.

dmrs = nrPDSCHDMRSConfig;
dmrs.DMRSConfigurationType = 2;
dmrs.DMRSLength = 2;
dmrs.DMRSAdditionalPosition = 1;
dmrs.DMRSTypeAPosition = 2;
dmrs.DMRSPortSet = 5;
dmrs.NIDNSCID = 10;
dmrs.NSCID = 0;

Assign the PDSCH DM-RS configuration object to DMRS property of PDSCH configuration object.

pdsch.DMRS = dmrs;

Generate PDSCH DM-RS symbols and indices for the specified carrier, PDSCH configuration, and output formatting name-value pair argument.

sym = nrPDSCHDMRS(carrier,pdsch,'OutputDataType','single')

sym = 496×1 single column vector

  -0.7071 - 0.7071i
  -0.7071 + 0.7071i
  -0.7071 + 0.7071i
   0.7071 + 0.7071i
   0.7071 + 0.7071i
  -0.7071 - 0.7071i
   0.7071 - 0.7071i
  -0.7071 + 0.7071i
   0.7071 - 0.7071i
  -0.7071 - 0.7071i
   0.7071 - 0.7071i
   0.7071 - 0.7071i
  -0.7071 + 0.7071i
   0.7071 + 0.7071i
   0.7071 + 0.7071i
      ⋮

ind = nrPDSCHDMRSIndices(carrier,pdsch,'IndexBase','0based','IndexOrientation','carrier')

ind = 496×1 uint32 column vector

   1252
   1253
   1258
   1259
   1264
   1265
   1270
   1271
   1276
   1277
   1282
   1283
   1288
   1289
   1294
      ⋮

Display the generated DM-RS symbols on the carrier resource grid.

grid = complex(zeros([carrier.NSizeGrid*12 carrier.SymbolsPerSlot pdsch.NumLayers]));
grid(ind+1) = sym;
imagesc(abs(grid(:,:,1)));
axis xy;
xlabel('OFDM Symbols');
ylabel('Subcarriers');
title('PDSCH DM-RS Resource Elements in the Carrier Resource Grid');

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 properties of the nrCarrierConfig object.

• SubcarrierSpacing

• CyclicPrefix

• NSizeGrid

• NStartGrid

• NSlot

pdsch — PDSCH configuration parameters

nrPDSCHConfig object

PDSCH configuration parameters, specified as an nrPDSCHConfig object. This function uses only these properties of the nrPDSCHConfig object.

• NSizeBWP

• NStartBWP

• ReservedPRB

• NumLayers

• MappingType

• SymbolAllocation

• PRBSet

• DMRS

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','IndexBase','0based' specifies nondefault resource element index formatting properties.

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

IndexOrientation — Indexing orientation of resource elements

'carrier' (default) | 'bwp'

Indexing orientation of resource elements, specified as the comma-separated pair consisting of 'IndexOrientation' and one of these values:

• 'carrier' — Indices are referenced with respect to the carrier grid.

• 'bwp' — Indices are referenced with respect to the bandwidth part.

Data Types: char | string

Output Arguments

ind — DM-RS RE indices

N-by-P matrix | M-by-3 matrix

DM-RS RE indices, returned as one of these values:

• N-by-P matrix — The function returns this type of value when 'IndexStyle' is set to 'index'. The matrix columns correspond to the antenna ports configured.

• M-by-3 matrix — The function returns this type of value when 'IndexStyle' is set 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.

Depending on the value of 'IndexBase', the function returns either 1-based or 0-based indices. Depending on the value of 'IndexOrientation', the function returns either carrier oriented indices or BWP oriented indices.

Data Types: uint32

References

[1] 3GPP TS 38.211. “NR; Physical channels and modulation.” 3rd Generation Partnership Project; Technical Specification Group Radio Access Network.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Version History

Introduced in R2020a

R2023a: C/C++ code generation updates

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