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ltePSBCHDRSIndices

PSBCH DM-RS resource element indices

Syntax

``ind = ltePSBCHDRSIndices(ue)``
``ind = ltePSBCHDRSIndices(ue,opts)``

Description

example

````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 in cell array `opts`.```

Examples

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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';`

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

Input Arguments

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

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

Data Types: `char`

Number of sidelink resource blocks, specified as an integer scalar from 6 to 110. (${N}_{\text{RB}}^{\text{SL}}$)

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

Data Types: `double`

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

Data Types: `char`

Output format options for resource element indices, specified as `'ind'` or `'sub'`, and `'1based'` or `'0based'`. You can specify a format for the indexing style and index base.

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: `'sub'` returns indices in subscript row style using the default one-based indexing style.

Data Types: `char` | `cell`

Output Arguments

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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.

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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 System Toolbox™ subframe orientation. For more information on mapping symbols to the resource element grid, see Resource Grid Indexing.

References

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