# Documentation

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# lteCellRSIndices

CRS resource element indices

## Syntax

``ind = lteCellRSIndices(enb)``
``ind = lteCellRSIndices(enb,ports)``
``ind = lteCellRSIndices(enb,ports,opts)``

## Description

````ind = lteCellRSIndices(enb)` returns a column vector of resource element (RE) indices for the cell-specific reference signal (RS), given the cell-wide settings in the `enb` structure. By default, the indices are returned in 1-based linear indexing form that can directly index elements of a 3-D array representing the subframe resource grid for all antenna ports. These indices are ordered as the reference signal modulation symbols should be mapped. Unlike other physical channels and signals, the indices for multiple antennas are concatenated into a single column rather than returned in a matrix with a column for each antenna. The indices for each antenna are concatenated because the number of indices varies across the antenna ports. ```
````ind = lteCellRSIndices(enb,ports)` returns a column vector of RE indices for antenna ports specified in the vector, `ports` (0,1,2,3), and cell-wide settings structure, `enb`. In this case, `CellRefP` is ignored if present in `enb` and `ports` is used instead. ```

example

````ind = lteCellRSIndices(enb,ports,opts)` formats the returned indices using options defined in `opts`.```

## Examples

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Generate zero-based cell-specific reference signal (CRS) resource element (RE) indices in subscript form for antenna port 2.

```enb = lteRMCDL('R.0'); enb.NCellID = 10; ind = lteCellRSIndices(enb,2,{'0based','sub'}); ind(1:4,:)```
```ans = 4x3 uint32 matrix 4 1 2 10 1 2 16 1 2 22 1 2 ```

In this case, each row of the generated matrix has three columns, which represent subcarrier, symbol, and antenna port, respectively.

## Input Arguments

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eNodeB cell-wide settings, specified as a structure that can contain 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

`CellRefP`Required

1, 2, 4

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

`CyclicPrefix`Optional

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

Cyclic prefix length

`DuplexMode`Optional

`'FDD'` (default), `'TDD'`

Duplexing mode, specified as:

• `'FDD'` for Frequency Division Duplex or

• `'TDD'` for Time Division Duplex

 The following parameters are dependent upon the condition that `DuplexMode` is set to `'TDD'`. `TDDConfig` Optional 0 (default), 1, 2, 3, 4, 5, 6 Uplink–downlink configuration `SSC` Optional 0 (default), 1, 2, 3, 4, 5, 6, 7, 8, 9 Special subframe configuration (SSC) `Nsubframe` Optional 0 (default), nonnegative scalar integer Subframe number

Antenna ports, specified as a numeric vector whose elements must be (0, 1, 2, 3).

Index generation options, specified as a character vector or a cell array of character vectors that can contain the following values.

OptionValuesDescription
Indexing style

`'ind'` (default), `'sub'`

Style for the returned indices, specified as one of the following options.

• `'ind'` — returns the indices in linear index form as a column vector (default)

• `'sub'` — returns the indices in `[subcarrier, symbol, antenna]` subscript row style. The number of rows in the output, `ind`, is the number of resource elements (NRE). Thus, `ind` is an NRE-by-3 matrix.

Index base

`'1based'` (default), `'0based'`

Base value of the returned indices. Specify `'1based'` to generate indices where the first value is one. Specify `'0based'` to generate indices where the first value is zero.

Data Types: `char` | `cell`

## Output Arguments

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Cell-specific reference signal RE indices, returned as a column vector. Optionally, can be returned as an NRE-by-3 matrix.

Data Types: `uint32`