# Documentation

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# ltePDCCHIndices

PDCCH resource element indices

## Syntax

• ind = ltePDCCHIndices(enb)
example
• ind = ltePDCCHIndices(enb,opts)
• ind = ltePDCCHIndices(enb,exreg,opts)
example

## Description

example

ind = ltePDCCHIndices(enb) returns a NRE-by-CellRefP matrix of one-based linear indexing RE indices given the structure enb. It returns the subframe resource element (RE) indices for the physical downlink control channels (PDCCH).

The NRE indices returned cover all PDCCH resources in the control region not already assigned to PCFICH or PHICH (see ltePDCCHInfo). They are ordered as the complete block of padded, interleaved, and shifted PDCCH modulation symbols that ready to be mapped, as described in TS 36.211 [1], Section 6.8.5.

ind = ltePDCCHIndices(enb,opts) allows control of the format of the returned indices through a cell array opts.

example

ind = ltePDCCHIndices(enb,exreg,opts) returns a matrix of indices, where the vector exreg explicitly defines resources not to be assigned to PDCCH. The exreg must contain valid resource element group (REG) indices but can be either zero-based or one-based throughout, and indices which do not fall within the control region are ignored.

## Examples

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Retrieve PDCCH resource element (RE) indices.

Create an RMC R.0 configuration structure and find its PDCCH RE indices. Display the size of the indices.

enb = lteRMCDL('R.0');
ind = ltePDCCHIndices(enb);
size(ind)
ans =

452     1

Explicitly exclude resources when retrieving PDCCH indices.

Create a cell-wide configuration structure initalized for RMC R.0. Generate RE indices for the PDCCH providing an empty matrix for the argument exreg so that no resources are excluded.

enb = lteRMCDL('R.0');
ind = ltePDCCHIndices(enb,[],'re');
numPDCCHwithNoExclusion = size(ind)
numPDCCHwithNoExclusion =

480     1

All RE indices are returned in the required mapping order.

Explicitly exclude the PCFICH and PHICH indices.

enb = lteRMCDL('R.0');
exreg = [ltePCFICHIndices(enb,'reg'); ltePHICHIndices(enb,'reg')];
ind = ltePDCCHIndices(enb,exreg,'re');
numPDCCHwithExclusion = size(ind)
numPDCCHwithExclusion =

452     1

This call returns the same result as the default syntax call, ltePDCCHIndices(enb).

## Input Arguments

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enb is a structure having the following fields.

Parameter FieldRequired or OptionalValuesDescription
NDLRBRequired

Integer within the range (6,...,110)

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

NCellIDRequired

Integer from 0 to 503

Physical layer cell identity

CyclicPrefixOptional

'Normal' (default), 'Extended'

Cyclic prefix length

CellRefPRequired

1, 2, 4

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

CFIRequired

1, 2, or 3

Control format indicator value

NgRequired

'Sixth', 'Half', 'One', 'Two'

HICH group multiplier

PHICHDurationOptional

'Normal' (default), 'Extended'

PHICH duration

DuplexModeOptional

'FDD' (default), 'TDD'

Duplexing mode, specified as:

• 'FDD' for Frequency Division Duplex or

• 'TDD' for Time Division Duplex

The following field is required when DuplexMode is set to 'TDD'.
TDDConfigOptional

0 (default), 1, 2, 3, 4, 5, 6

NSubframeRequired

Integer greater than 0

Subframe number

Data Types: struct

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.

Indexing unit

're' (default), 'reg'

Unit of the returned indices. Specify 're' to indicate that the returned values correspond to individual resource elements (REs). Specify 'reg' to indicate that the returned values correspond to resource element groups (REGs).

Data Types: char | cell

Resources excluded from PDCCH, specified as a vector. This vector explicitly defines those resources not to be assigned to PDCCH. exreg must contain valid resource element group (REG) indices but can be either zero-based or one-based throughout. Indices which do not fall within the control region are ignored.

Data Types: double

## Output Arguments

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PDCCH RE indices, returned as an NRE-by-CellRefP numeric matrix by default. The matrix contains one-based linear indexing RE indices. Each column of ind identifies the same set of NRE subframe resource elements but with indices offset to select them in a different antenna "page" of the 3-D resource array.

The default matrix of indices in a one-based linear indexing style which can directly index elements of an M-by-N-by-CellRefP array, where M is the number of symbols, and N is the number of subcarriers representing the subframe grid across CellRefP antenna ports.

Data Types: double

## References

[1] 3GPP TS 36.211. "Physical Channels and Modulation." 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA). URL: http://www.3gpp.org.