# ltePCFICHIndices

PCFICH resource element indices

## Syntax

``ind = ltePCFICHIndices(enb)``
``ind = ltePCFICHIndices(enb,opts)``

## Description

````ind = ltePCFICHIndices(enb)` returns the 16-by-`CellRefP` matrix of subframe resource element (RE) indices for the physical control format indicator channel (PCFICH), given the `enb` input structure. By default, the indices are returned in 1-based linear indexing form that directly indexes elements of a 3-D array representing the subframe resource grid for `CellRefP` antenna ports. Each column of `ind` contains per-antenna indices for 16 resource elements in one of the `CellRefP` array planes. The rows are ordered as the PCFICH modulation symbols should be mapped. The indices can also be returned in a number of alternative indexing formats. The PCFICH is always transmitted on 16 resource elements, or 4 resource element groups (REG), in the first OFDM symbol of a subframe however their locations depend on the `NCellID` and `NDLRB` parameters. ```

example

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

## Examples

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This example generates physical CFI channel (PCFICH) resource element (RE) indices for two different physical layer cell identity values.

To show the effects of the physical layer cell identity, `NCellID`, on the indices, first set it to `0`. Generate and display the PCFICH indices.

```enb.NDLRB = 50; enb.NCellID = 0; enb.CyclicPrefix = 'Normal'; enb.CellRefP = 1; ind = ltePCFICHIndices(enb,{'0based','reg'}); disp(ind)```
``` 0 150 300 450 ```

Next, set the physical layer cell identity, `NCellID`, to `1`. Regenerate and display the PCFICH indices.

```enb.NCellID = 1; ind = ltePCFICHIndices(enb,{'0based','reg'}); disp(ind)```
``` 6 156 306 456 ```

## Input Arguments

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

Parameter FieldRequired or OptionalValuesDescription
`NDLRB`Required

Scalar integer from 6 to 110

Number of downlink resource blocks. (${N}_{\text{RB}}^{\text{DL}}$)

`NCellID`Required

Integer from 0 to 503

Physical layer cell identity

`CyclicPrefix`Optional

`'Normal'` (default), `'Extended'`

Cyclic prefix length

`CellRefP`Optional

1 (default), 2, 4

Number of cell-specific reference signal (CRS) antenna ports

Output format, base, and unit of generated indices, specified as one of these forms.

• ```'format base unit'```

• ```"format base unit"```

• `{'format','base','unit'}`

• `["format","base","unit"]`

Where `format`, `base`, and `unit` are defined in this table.

 Option Values Description `format` `'ind'` (default), `'sub'` Output format of generated indicesTo return the indices as a column vector, specify this option as `'ind'`.To return the indices as an NRE-by-3 matrix, where NRE is the number of REs, specify this option as `'sub'`. Each row of the matrix contains the subcarrier, symbol, and antenna port as its first, second, and third element, respectively. `base` `'1based'` (default), `'0based'` Index baseTo generate indices whose first value is `1`, specify this option as `'1based'`. To generate indices whose first value is `0`, specify this option as `'0based'`. `unit` `'re'` (default), `'reg'` Unit of returned indicesTo indicate that the returned values correspond to individual resource elements (REs), specify this option as `'re'`. To indicate that the returned values correspond to resource element groups (REGs), specify this option as `'reg'`.

Example: `'ind 0based reg'`, ```"ind 0based reg"```, `{'ind','0based','reg'}`, and `["ind","0based","reg"]` specify the same output options.

Data Types: `char` | `string` | `cell`

## Output Arguments

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Subframe PCFICH RE indices, returned as a numeric matrix of size 16-by-`CellRefP`. Each column of `ind` contains per-antenna indices for 16 resource elements in one of the `CellRefP` array planes. The rows are ordered as the PCFICH modulation symbols should be mapped.