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EPDCCH DM-RS resource element indices


ind = lteEPDCCHDMRSIndices(enb,chs)
ind = lteEPDCCHDMRSIndices(enb,chs,opts)



ind = lteEPDCCHDMRSIndices(enb,chs) returns indices of the Enhanced Physical Downlink Control Channel Demodulation Reference Signal (EPDCCH DM-RS) resource elements (RE) associated with an EPDCCH transmission candidate in a subframe. By default, ind is a column vector of indices in one-based linear indexing form. Use this form to directly index the EPDCCH DM-RS REs of an N-by-M-by-4 array that represents the subframe resource grid across the four possible EPDCCH antenna ports (p = 107...110). You can also generate alternative index representations. The order of the indices is the same as required for the complex EPDCCH DM-RS symbols mapping. lteEPDCCHDMRS generates these symbols.

The indices are parameterized in terms of a configured PRB pair set which defines:

  • the overall set of possible EPDCCH candidates and

  • the aggregation of one or more consecutive enhanced control channel elements (ECCE). This aggregation identifies the specific EPDCCH instance that the DM-RS are associated with.

The DM-RS indices are created only for the specific PRB pairs and antenna ports that the corresponding EPDCCH is mapped to. They do not account for any external precoding operations.

For a localized EPDCCH transmission, the EPDCCH is associated with a single antenna port from p = 107...110, dependent on the RNTI and ECCEs selected. Thus, the DM-RS antenna port indices (1...4 respectively, if one-based) are output for that single port.

For a distributed transmission, the EPDCCH is mapped to two antenna ports in an alternating fashion. Therefore, the DM-RS indices are generated for the PRBs in both ports: p = 107,109 for normal cyclic prefix and p = 107,108 for extended cyclic prefix. The output is ordered so that the symbols for the lowest antenna index plane come first. These indices are suitable for indexing an N-by-M-by-4 array representing the subframe resource grid across the four possible EPDCCH antenna ports (p = 107...110).

This syntax returns an NRE length column vector of one-based linear indices for the DM-RS resource elements associated with a particular EPDCCH candidate. The function is initialized according to the cell-wide settings, enb, and the EPDCCH transmission configuration, chs.

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


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Specify the cell-wide settings and channel transmission configuration in parameter structures enb and chs.

enb = struct('CyclicPrefix','Normal','DuplexMode','FDD');
enb.NDLRB = 6;
enb.NSubframe = 0;
chs.EPDCCHECCE = [0 7];
chs.EPDCCHType = 'Localized';
chs.EPDCCHPRBSet = 2:3;
chs.RNTI = 1;

Create the EPDCCH DM-RS indices for an EPDCCH having eight ECCEs.

ind = lteEPDCCHDMRSIndices(enb,chs)
ind = 12x1 uint32 column vector


Input Arguments

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

Parameter FieldRequired or OptionalValuesDescription

Scalar integer from 6 to 110

Number of downlink resource blocks. (NRBDL)


'Normal' (default), 'Extended'

Cyclic prefix length


0 (default), nonnegative scalar integer

Subframe number


'FDD' (default), 'TDD'

Duplexing mode, specified as one of the following:

  • 'FDD' — Frequency division duplex (default)

  • 'TDD' — Time division duplex

The following parameters apply when DuplexMode is set to 'TDD'.


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

Uplink–downlink configuration


0 (default), 1, 2, 3, 4, 5, 6, 7, 8, 9

Special subframe configuration (SSC)

Channel-specific transmission configuration, specified as a structure that can contain the following parameter fields.

Parameter FieldRequired or OptionalValuesDescription

1-element or 2-element vector specifying the 0-based ECCE index or inclusive [begin, end] ECCE index range according to the aggregation level L (L = end – begin + 1). The number of ECCEs in the candidate must be a power of 2.

If no transmission is required, leave this parameter empty.

The set of one or several consecutive ECCEs defining the EPDCCH transmission candidate in the overall EPDCCH set.


'Localized', 'Distributed'

EPDCCH transmission type


Vector of zero-based indices for the PRB pairs corresponding to the EPDCCH PRB set. The number of PRB pair indices must be a power of 2.

If no transmission is required, leave this parameter empty.

EPDCCH PRB pair indices

The following parameters apply when EPDCCHType is set to 'Localized'.


0 (default), scalar integer

Radio network temporary identifier (RNTI) value (16 bits)

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):

Indexing style

'ind' (default), 'mat', 'sub'

Style for the returned indices, specified as one of the following:

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

  • 'mat' — returns the indices in linear index form as a matrix, where each column contains indices for an individual port.

  • '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.

Indexing format

'rsonly' (default), 'rs+unused'

RE locations mode of the returned indices.

  • 'rsonly' — returns only active DM-RS locations (default)

  • 'rs+unused' — also includes all RE locations, which should be unused because of DM-RS transmission on other EPDCCH antenna ports p = 107...110 that are not used by this EPDCCH transmission

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

Data Types: char | string | cell

Output Arguments

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EPDCCH DM-RS resource element indices, returned by default as a numeric vector of length NRE-by-1. Optionally, for subscript-specific indexing style [subcarrier, symbol, antenna], ind is returned as an NRE-by-3 numeric matrix. NRE is the number of subframe resource elements. You can also return the indices in a linear indexing matrix, where each column contains indices for an individual antenna port. By default, the indices are returned in one-based linear indexing form, which you can use to directly index the EPDCCH DM-RS resource elements.

Data Types: double

Introduced in R2014b