nrPDSCHDMRSIndices

R2026b

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 arguments. Unspecified options take default values. For example, IndexStyle="subscript" specifies nondefault resource element index formatting properties.

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 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.

Example: IndexStyle="subscript" 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 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™.

GPU Code Generation
Generate CUDA® code for NVIDIA® GPUs using GPU 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.