# lteSSSS

## Syntax

``s = lteSSSS(ue)``

## Description

example

````s = lteSSSS(ue)` returns `s`, a column vector containing the secondary sidelink synchronization signal (SSSS) values for user equipment settings `ue`. For more information, see Secondary Sidelink Synchronization Signal.```

## Examples

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Generate and plot the BPSK sidelink secondary synchronization signal values for NSLID = 10.

```ssss = lteSSSS(struct('NSLID',10)); scatterplot(ssss) grid```

Generate all possible SSSS sequences, contained as columns in a 124-by-336 matrix.

```ssssfn = @(x)lteSSSS(struct('NSLID',x)); allssss = cell2mat(arrayfun(ssssfn,[0:335],'UniformOutput',false));```

Generate all possible SSSSs for V2X sidelink.

```sfn = @(x)lteSSSS(struct('NSLID',x,'SidelinkMode','V2X')); s = cell2mat(arrayfun(sfn,0:335,'UniformOutput',false));```

## Input Arguments

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User equipment settings, specified as a structure containing the following fields.

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

Data Types: `char` | `string`

Physical layer sidelink synchronization identity, specified as an integer in the interval [0, 335].

Data Types: `double`

## Output Arguments

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SSSS values, returned as a 124-by-1 complex-valued vector. These values are created for the user equipment settings in the `ue` structure. For more information, see Secondary Sidelink Synchronization Signal.

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The secondary sidelink synchronization signal (SSSS) is transmitted in the central 62 resource elements of two adjacent SC-FDMA symbols in a synchronization subframe. The same sequence of 62 complex values is repeated in each of the symbols, resulting in a 124-by-1 element vector returned by the `lteSSSS` function. The values of this sequence are ordered as they should be mapped into the resource elements of the adjacent symbols using `lteSSSSIndices`. If a terminal is transmitting SSSS then it should be sent every 40 ms for D2D sidelink or every 160 ms for V2X sidelink, with the exact subframe dependent on the RCC signaled subframe number offset (syncOffsetIndicator-r12). The SSSS is sent on antenna port 1020, along with the primary sidelink synchronization signal (PSSS). A synchronization subframe also contains the PSBCH, which is sent on antenna port 1010. The transmission power of the SSSS symbols should be the same as the PSBCH therefore they should be scaled by $\sqrt{72}{62}}$ in a subframe. No PSCCH or PSSCH transmission will occur in a sidelink subframe configured for synchronization purposes.

As specified in TS 36.211, Section 9.7, the SSSS identity assignment depends on the network coverage. The set of all ${N}_{\text{ID}}^{\text{SL}}$ is divided into two sets, id_net {0, ..., 167} and id_oon {168, ..., 335}, which are used by terminals that are in-network and out-of-network coverage, respectively. The sidelink physical layer cell identity number, ${N}_{\text{ID}}^{\text{SL}}$, corresponds to the `lteSSSS` input UE settings structure field `ue`.`NSLID`. Within each set, all identities result in the same SSSS. For an in-network terminal, the `ue`.`NSLID` value corresponds to the RRC sidelink synchronization signal identity (slssid-r12) associated with the cell.

### Secondary Sidelink Synchronization Signal Indexing

Use the indexing function, `lteSSSSIndices`, and the corresponding sequence function, `lteSSSS`, to populate the resource grid for the desired subframe number. The SSSS values are output by `lteSSSS`, ordered as they should be mapped, applying frequency-first mapping into the resource elements of the adjacent symbols using `lteSSSSIndices`. When indexing is zero-based, the SC-FDMA symbols used are {11,12} for normal cyclic prefix and {9, 10} for extended cyclic prefix.

Note

The indicated symbol indices are based on TS 36.211, Section 9.7. However to align with the LTE Toolbox™ subframe orientation, these indices are expanded from symbol index per slot to symbol index per subframe.

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