# lteCellRSIndices

CRS resource element indices

## 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,opts) returns RE indices in a format specified by opts.

ind = lteCellRSIndices(enb,ports) returns RE indices for antenna ports specified in the vector ports. In this case, the CellRefP field of enb is ignored, and ports is used instead.

example

ind = lteCellRSIndices(enb,ports,opts) returns RE indices for the specified antenna ports and formatting options.

## 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 containing these parameter fields.

Parameter FieldRequired or OptionalValuesDescription
NDLRBRequired

Scalar integer from 6 to 110

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

NCellIDRequired

Integer from 0 to 503

Physical layer cell identity

CellRefPRequired

1, 2, 4

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

CyclicPrefixOptional

'Normal' (default), 'Extended'

Cyclic prefix length

DuplexModeOptional

'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'. Nsubframe Required 0 (default), nonnegative scalar integer Subframe number TDDConfig Optional 0, 1 (default), 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)

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

Index generation options, specified as a character vector, cell array of character vectors, or string array. For convenience, you can specify several options as a single character vector or string scalar by a space-separated list of values placed inside the quotes. Values for opts when specified as a character vector include (use double quotes for string):

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 1. Specify '0based' to generate indices where the first value is 0.

Example: 'ind 0based', "ind 0based", {'ind','0based'}, ["ind","0based"] specify the same formatting options.

Data Types: char | string | 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

## Version History

Introduced in R2014a