ltePSBCHDRSIndices

PSBCH DM-RS resource element indices

Syntax

ind = ltePSBCHDRSIndices(ue)

ind = ltePSBCHDRSIndices(ue,opts)

Description

ind = ltePSBCHDRSIndices(ue) returns the subframe resource element (RE) indices for the demodulation reference signal (DM-RS) associated with a PSBCH transmission for the specified UE settings structure. By default, the indices are returned in one-based linear indexing form. You can use this form to directly index elements of a matrix representing the subframe resource grid for antenna port 1010. For more information, see PSBCH Demodulation Reference Signal Indexing.

ind = ltePSBCHDRSIndices(ue,opts) formats the returned indices using options specified by opts.

Examples

Create PSBCH DM-RS Values

Write the complex PSBCH DM-RS values into the PSBCH DM-RS resource elements in a synchronization subframe for both D2D and V2X sidelink modes and display an image of their locations.

Create a user equipment settings structure and an empty resource grid subframe for 10 MHz bandwidth and D2D sidelink mode.

ue = struct();
ue.NSLRB = 50;
ue.CyclicPrefixSL = 'Normal';
ue.NSLID = 1;
subframe_D2D = lteSLResourceGrid(ue);

Generate PSBCH DM-RS indices and load PSBCH DM-RS values into subframe.

psbchdrs_indices = ltePSBCHDRSIndices(ue);
subframe_D2D(psbchdrs_indices) = ltePSBCHDRS(ue);

Change user equipment settings to V2X sidelink mode.

ue.SidelinkMode = 'V2X';

Generate the grid subframe, the PSBCH DM-RS indices and load PSBCH DM-RS values into subframe_V2X.

subframe_V2X = lteSLResourceGrid(ue);
psbchdrs_indices = ltePSBCHDRSIndices(ue);
subframe_V2X(psbchdrs_indices) = ltePSBCHDRS(ue);

Display the PSBCH DM-RS locations for both sidelink modes.

subplot(2,1,1);
imagesc(100*abs(subframe_D2D)); 
axis xy; title('D2D');
subplot(2,1,2);
imagesc(100*abs(subframe_V2X)); 
axis xy; title(ue.SidelinkMode);

Input Arguments

ue — User equipment settings

structure

UE equipment settings, specified as a parameter structure containing these fields:

SidelinkMode — Sidelink mode

'D2D' (default) | 'V2X' | optional

Sidelink mode, specified as 'D2D' or 'V2X'.

Data Types: char | string

NSLRB — Number of sidelink resource blocks

integer scalar from 6 to 110

Number of sidelink resource blocks, specified as an integer scalar from 6 to 110.

Example: 6, which corresponds to a channel bandwidth of 1.4 MHz.

Data Types: double

CyclicPrefixSL — Cyclic prefix length

'Normal' (default) | 'Extended' | optional

Cyclic prefix length, specified as 'Normal' or 'Extended'.

Data Types: char | string

opts — Output format options for resource element indices

character vector | cell array of character vectors | string array

Output format options for resource element indices, 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) :

Category	Options	Description
Indexing style	'ind' (default)	The returned indices are in linear index style.
	'sub'	The returned indices are in [subcarrier,symbol,port] subscript row style.
Index base	'1based' (default)	The returned indices are one-based.
	'0based'	The returned indices are zero-based.

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

Data Types: char | string | cell

Output Arguments

ind — Resource element indices

integer column vector | three-column integer matrix

Resource element indices, returned as an integer column vector or a three-column integer matrix. By default, the indices are returned in a 144-by-1 column vector in one-based linear indexing form. You can use this form to directly access elements of a matrix representing the subframe resource grid for antenna port 1010. For V2X sidelink, the output is a 216-by-1 complex column for the three DM-RS symbols in a subframe. To specify alternative indexing formats, use the opts input argument.

More About

PSBCH Demodulation Reference Signal Indexing

Use the indexing function, ltePSBCHDRSIndices, and the corresponding sequence function, ltePSBCHDRS, to index the resource grid for any synchronization subframe number. The indices are ordered as the PSBCH DM-RS symbols should be, applying frequency-first mapping, into the two DM-RS SC-FDMA symbols. For more information on mapping symbols to the resource element grid, see Resource Grid Indexing.

PSBCH Demodulation Reference Signal

The PSBCH demodulation reference signal (DM-RS) is transmitted alongside the ltePSBCH values in the central 72 resource elements and in two SC-FDMA symbols in a synchronization subframe for D2D sidelink mode and three SC-FDMA symbols for V2X.. For zero-based indexing, the SC-FDMA symbol indices are {3,10} for normal cyclic prefix and {2,8} for extended cyclic prefix. These are the same symbols used by the PUSCH DM-RS, see ltePUSCHDRSIndices. For the V2X sidelink mode, the symbol indices are {4,6,9}.

Note

The indicated symbol indices are based on TS 36.211, Section 9.8, but expanded from symbol index per slot to symbol index per subframe to align with the LTE Toolbox™ subframe orientation. For more information on mapping symbols to the resource element grid, see Resource Grid Indexing.

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.

Version History

Introduced in R2016b