# lteSLSCFDMAInfo

## Syntax

``info = lteSLSCFDMAInfo(ue)``

## Description

example

````info = lteSLSCFDMAInfo(ue)` returns a structure containing information related to the sidelink SC-FDMA modulation performed by `lteSLSCFDMAModulate`, using the specified UE settings structure.For details, see Sidelink SC-FDMA Modulation.```

## Examples

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Calculate the sampling rate of a 5 MHz sidelink waveform after sidelink SC-FDMA modulation.

Create a UE settings structure. Specify 25 resource blocks, which corresponds to 5 MHz channel bandwidth.

`ue = struct('NSLRB',25);`

For the specified channel bandwidth, find the sidelink SC-FDMA modulation sampling rate.

```slscfdmaInfo = lteSLSCFDMAInfo(ue); samplingRate = slscfdmaInfo.SamplingRate```
```samplingRate = 7680000 ```

## Input Arguments

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

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`

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

Data Types: `char` | `string`

Number of time-domain samples over which windowing and overlapping of sidelink SC-FDMA symbols is applied, specified as a positive integer scalar.

`ue`.`Windowing` must be even. For the `ue`.`Windowing` field, the default depends on `NSLRB` and `CyclicPrefixSL`.

Data Types: `double`

Data Types: `struct`

## Output Arguments

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Sidelink SC-FDMA modulated waveform information, returned as a parameter structure containing these fields:

Sampling rate of the time-domain sidelink waveform, in Hz, returned as a positive numeric scalar. `SamplingRate` = `Nfft` × (30.72e6 / 2048).

Number of FFT points, returned as a positive integer scalar. `Nfft` is a function of the number of resource blocks, ${N}_{\text{RB}}^{\text{SL}}$.

`NSLRB` (${N}_{\text{RB}}^{\text{SL}}$)`Nfft`

6

128

15

256

25

512

50

1024

75

2048

100

2048

In general, `Nfft` is the smallest power of 2 greater than or equal to (12 × ${N}_{\text{RB}}^{\text{SL}}$) / 0.85. Specifically, `Nfft` is the smallest FFT that spans all subcarriers and results in no more than 85% of bandwidth occupancy (12 × ${N}_{\text{RB}}^{\text{SL}}$ / `Nfft`).

Number of time-domain samples over which windowing and overlapping of sidelink SC-FDMA symbols is applied, returned as a positive integer scalar.

Cyclic prefix length in symbols for each sidelink SC-FDMA symbol in a subframe, returned as an NSYM-by-1 integer vector. NSYM is 14 for normal cyclic prefix and 12 for extended cyclic prefix.

The vector returned for `info`.`CyclicPrefixLengths` depends on the FFT size.

• When `info`.`Nfft` = `2048`, then `CyclicPrefixLengths` is:

• ```[160 144 144 144 144 144 144 160 144 144 144 144 144 144]``` for normal cyclic prefix

• ```[512 512 512 512 512 512 512 512 512 512 512 512]``` for extended cyclic prefix

• For other values of `info`.`Nfft`, these element values in `CyclicPrefixLengths` are scaled by `info`.`Nfft` / 2048.

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The sidelink SC-FDMA modulation processing in `lteSLSCFDMAModulate` performs IFFT calculation, half-subcarrier shifting, cyclic prefix insertions, and optional raised-cosine windowing and overlapping of adjacent sidelink SC-FDMA symbols. TS 36.211 specifies that for PSSCH (Section 9.3.6), PSCCH (9.4.6), PSDCH (9.5.6) and PSBCH (9.6.6), resource elements in the last SC-FDMA symbol within a subframe should be counted in the mapping process but not transmitted. Therefore, before performing the IFFT, the last SC-FDMA symbol of each subframe in the input resource grid is set to zero.

For sidelink SC-FDMA modulation, calling `lteSLSCFDMAModulate` on a multi-subframe array of resource grids is recommended.

• When the resource element grid input to `lteSLSCFDMAModulate` spans multiple subframes, the windowing and overlapping is applied between all adjacent SC-FDMA symbols, including the last symbol of the previous subframe and the first symbol of the next subframe. Multi-subframe modulation processing results in a waveform that does not have discontinuities between subframes.

• A time-domain waveform that concatenates individually modulated subframes has discontinuities at the start and end of each subframe. To avoid these discontinuities, the resulting multi-subframe time-domain waveform must be created by manually overlapping symbols at the subframe boundaries.

• If the value for windowing is zero, issues concerning concatenation of subframes before sidelink SC-FDMA modulation do not apply.

If `ue`.`Windowing` is absent, `info`.`Windowing` returns a default value chosen as a function of NRB. The chosen value is a compromise between:

• The effective duration of cyclic prefix, and therefore the channel delay spread tolerance

• The spectral characteristics of the transmitted signal, not considering any additional FIR filtering

## Version History

Introduced in R2016b