lteDMRSIndices

UE-specific DM-RS resource element indices

Syntax

ind = lteDMRSIndices(enb,chs)

ind = lteDMRSIndices(enb,chs,opts)

Description

ind = lteDMRSIndices(enb,chs) returns the indices of the downlink UE-specific demodulation reference signal (DM-RS) resource elements (RE) in a subframe, given structures containing the cell-wide settings, and the PDSCH settings. For more information, see DM-RS Associated with PDSCH.

ind = lteDMRSIndices(enb,chs,opts) formats the returned indices using options specified by opts.

Examples

Generate PDSCH DM-RS Indices

Generate DM-RS Resource Element (RE) indices in default format for RMC R.28.

Initialize cell-wide parameters to RMC R.28 using the lteRMCDL function. Use enb.PDSCH for the channel configuration structure. Generate the RE indices.

enb = lteRMCDL('R.28');
ind = lteDMRSIndices(enb,enb.PDSCH);

View first four rows of index column vector

size(ind)

ans = 1×2

    24     1

ind(1:4)

ans = 4×1 uint32 column vector

   1801
   1805
   1809
   3603

Generate Zero-Based DM-RS Indices

Generate 0-based Resource Element indices in subscript form for RMC R.28. The resultant matrix has three columns, with each row representing [subcarrier, symbol, antenna port].

Initialize cell-wide parameters to RMC R.28 using the lteRMCDL function.

enb = lteRMCDL('R.28');

Generate zero-based RE indices in subscript form.

ind = lteDMRSIndices(enb,enb.PDSCH,{'0based','sub'});

View first four rows of index matrix.

size(ind)

ans = 1×2

    24     3

ind(1:4,:)

ans = 4×3 uint32 matrix

   0   3   0
   4   3   0
   8   3   0
   2   6   0

Input Arguments

enb — eNodeB cell-wide settings

structure

eNodeB cell-wide settings, specified as a structure containing these parameter fields:

Parameter Field	Required or Optional	Values	Description
NDLRB	Required	Scalar integer from 6 to 110	Number of downlink resource blocks ($$N_{\text{RB}}^{\text{DL}}$$)
NSubframe	Required	0 (default), nonnegative scalar integer	Subframe number
CyclicPrefix	Optional	'Normal' (default), 'Extended'	Cyclic prefix length
DuplexMode	Optional	'FDD' (default), 'TDD'	Duplexing mode, specified as either: 'FDD' for Frequency Division Duplex 'TDD' for Time Division Duplex
The following parameters are dependent upon the condition that DuplexMode is set to 'TDD'.
TDDConfig	Optional	0, 1 (default), 2, 3, 4, 5, 6	Uplink–downlink configuration
SSC	Optional	0 (default), 1, 2, 3, 4, 5, 6, 7, 8, 9	Special subframe configuration (SSC)
The following parameter is only applicable when TxScheme is set to 'Port5'.
NCellID	Required	Integer from 0 to 503	Physical layer cell identity

chs — PDSCH-specific channel transmission configuration

structure

PDSCH-specific channel transmission configuration, specified as a structure that can contain these parameter fields.

Parameter Field	Required or Optional	Values	Description
PRBSet	Required	Integer column vector or two-column matrix	Zero-based physical resource block (PRB) indices corresponding to the slot wise resource allocations for this PDSCH. PRBSet can be assigned as: a column vector, the resource allocation is the same in both slots of the subframe, a two-column matrix, this parameter specifies different PRBs for each slot in a subframe, a cell array of length 10 (corresponding to a frame, if the allocated physical resource blocks vary across subframes). PRBSet varies per subframe for the RMCs 'R.25'(TDD), 'R.26'(TDD), 'R.27'(TDD), 'R.43'(FDD), 'R.44', 'R.45', 'R.48', 'R.50', and 'R.51'.
TxScheme	Optional	'Port5' (default), 'Port7-8', 'Port8', 'Port7-14'	DM-RS-specific transmission scheme, specified as one of the following options. Transmission scheme Description 'Port5' Rel-8 single-antenna port, port 5 'Port7-8' Rel-9 single-antenna port, port 7 if NLayers is 1. Rel-9 dual-layer transmission, ports 7 and 8 if NLayers is 2. 'Port8' Rel-9 single-antenna port, port 8 'Port7-14' Rel-10 up to 8 layer transmission, ports 7–14 if NLayers a value from 1 to 8.
NLayers	Optional	1 (default), 2, 3, 4, 5, 6, 7, 8	Number of transmission layers.
NTxAnts	Optional	0 (default), nonnegative integer	Number of transmission antenna ports. This argument is present only for UE-specific demodulation reference symbols.

opts — Index generation options

character vector | cell array of character vectors | string array

Index generation options, specified as a character vector, cell array of character vectors, or string array. For convenience, you can specify several options as a single character vector or string scalar by a space-separated list of values placed inside the quotes. Values for opts when specified as a character vector include (use double quotes for string):

Option	Values	Description
Indexing style	'ind' (default), 'mat', 'sub'	Style for the returned indices, specified as one of the following options. 'ind' — returns the indices as an NRE-by-1 vector (default) 'mat' — returns the indices as a matrix. If not precoded, each column contains indices for an individual layer/port. If precoded, each column contains symbols for a transmit antenna. To form a matrix, a column can contain duplicate entries. 'sub' — returns the indices as an NRE-by-3 matrix. in [subcarrier, symbol, antenna] subscript row style. NRE is the number of resource elements.
Index base	'1based' (default), '0based'	Base value of the returned indices. Specify '1based' to generate indices where the first value is 1. Specify '0based' to generate indices where the first value is 0.
Indexing format	'rsonly' (default), 'rs+unused'	Format for the returned indices, specified as one of the following options. 'rsonly' — returns only active DM-RS symbols (default) 'rs+unused' — also includes zeros for the resource element (RE) locations that should be unused because of DM-RS transmission on another port or layer. This format is equivalent to precoding with NTxAnts set to NLayers.

Example: 'ind 1based rs+unused', "ind 1based rs+unused", {"ind","1based","rs+unused"]or {'ind','1based','rs+unused'} specify the same formatting options.

Example: 'ind rsonly', "ind rsonly", {'ind','rsonly'}, or ["ind","rsonly"] specify the same formatting options.

Data Types: char | string | cell

Output Arguments

ind — DM-RS resource element indices

linear indexing N_RE-by-1 column vector (default) | linear indexing matrix | numeric 3-column matrix

DM-RS resource element indices, returned as a linear indexing N_RE-by-1 column vector, a linear indexing matrix, or a numeric 3-column matrix. The opts input offers alternative output styles or formats.

ind can directly index the DM-RS elements in an M-by-N-by-P array representing the subframe grid across either the non-precoded PDSCH layers, or precoded transmit antennas. M is the number of subcarriers, N is the number of symbols, and P is the number of layers, or antennas.

For more information, see DM-RS Associated with PDSCH.

Data Types: uint32

More About

DM-RS Associated with PDSCH

As specified in TS 36.211, Section 6.10.3, UE-specific demodulation reference signal (DM-RS) associated with the physical downlink shared channel (PDSCH):

• are transmitted in a single subframe on antenna ports p=5, p=7, p=8, or p=7, 8,..., (NLayers+6).

• are present and are a valid reference for PDSCH demodulation only if the PDSCH transmission is associated with the corresponding antenna port according to TS 36.213, Section 7.1.

• are transmitted only on the physical resource blocks upon which the corresponding PDSCH is mapped.

These DM-RS are for use with Release 8, 9, and 10 non-codebook-based PDSCH transmission schemes.

References

[1] 3GPP TS 36.211. “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation.” 3rd Generation Partnership Project; Technical Specification Group Radio Access Network. URL: https://www.3gpp.org.

[2] 3GPP TS 36.213. “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures.” 3rd Generation Partnership Project; Technical Specification Group Radio Access Network. URL: https://www.3gpp.org.

Version History

Introduced in R2014a