# lteCSIRS

Channel state information reference signal

## Syntax

``sym = lteCSIRS(enb)``
``sym = lteCSIRS(enb,opts)``

## Description

````sym = lteCSIRS(enb)` returns the channel state information reference signal (CSI-RS) symbols for transmission in a single subframe on up to eight antenna ports (p = 15,...,22). See lteCSIRS Processing.```

example

````sym = lteCSIRS(enb,opts)` formats the returned symbols using options specified by `opts`.```

## Examples

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Generate CSI-RS symbols and combine them with a 10 MHz, release 8, port 0 PDSCH subframe resource grid.

Initialize a reference channel structure. Create a 10 MHz, release 8, port 0 PDSCH configuration parameter structure. Set subframe number to 1, number of CSI-RS antenna ports to 8, CSI-RS configuration to 0, and CSIRSPeriod to 6.

```rmc = lteRMCDL('R.2','FDD',1); rmc.NSubframe = 1; rmc.CSIRefP = 8; rmc.CSIRSConfig = 0; rmc.CSIRSPeriod = 6;```

The 8 antenna ports are ports 15 to 22. The setting for `CSIRSPeriod` is `Icsi-rs`, which equals [ `Tcsi-rs` `Dcsi-rs`]=[10 1].

Create a 3-D resource grid to contain the subframes for all eight CSI-RS ports.

`rgrid = lteResourceGrid(rmc,rmc.CSIRefP);`

Write the release 8 port 0 transmission into the first plane of the resource grid.

`[wave,rgrid(:,:,1)] = lteRMCDLTool(rmc,[1,0,0,1]);`

Create the CSI-RS symbols for ports 15 to 22. Overwrite all ports included in the port 0 transmission with the actual CSI-RS and unused RE.

`rgrid(lteCSIRSIndices(rmc,'rs+unused')) = lteCSIRS(rmc,'rs+unused');`

## 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

`NSubframe`Required

0 (default), nonnegative scalar integer

Subframe number

`NFrame`Optional

0 (default), nonnegative scalar integer

Frame number

`CellRefP` is only used when the `Indexing format` option for indexing generation is`'rs+unused'`
`CellRefP`Optional

1 (default), 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 apply when `DuplexMode` is set to `'TDD'`.

`TDDConfig`Optional

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

`SSC`Optional

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

Special subframe configuration (SSC)

`CSIRSPeriod`Optional

`'On'` (default), `'Off'`, `Icsi-rs` (0,...,154), ```[Tcsi-rs Dcsi-rs]```. You can also specify values in a cell array of configurations for each resource.

See note.

CSI-RS subframe configurations for one or more CSI-RS resources. Multiple CSI-RS resources can be configured from a single common subframe configuration or from a cell array of configurations for each resource.

The following CSI-RS resource parameters apply only when `CSIRSPeriod` sets one, or more CSI-RS subframe configurations to any value other than `'Off'`. Each parameter length must be equal to the number of CSI-RS resources required.

`CSIRSConfig`Required

Nonnegative scalar integer

Array CSI-RS configuration indices. See TS 36.211, Table 6.10.5.2-1.

`CSIRefP`Required

1 (default), 2, 4, 8

Array of number of CSI-RS antenna ports

`NCSIID`Optional

Nonnegative scalar integer

CSI-RS scrambling identity. If this field is not present, then `NCellID` is used as the identity.

`ZeroPowerCSIRSPeriod`Optional

`'Off'` (default), `'On'`, `Icsi-rs` (0,...,154), ```[Tcsi-rs Dcsi-rs]```. You can also specify values in a cell array of configurations for each resource.

See note.

Zero power CSI-RS subframe configurations for one or more zero power CSI-RS resource configuration index lists. Multiple zero power CSI-RS resource lists can be configured from a single common subframe configuration or from a cell array of configurations for each resource list.

The following zero power CSI-RS resource parameter is only required if one, or more of the above zero power subframe configurations are set to any value other than `'Off'`.

`ZeroPowerCSIRSConfig`Required

16-bit bitmap character vector or string scalar (truncated if not 16 bits or `'0'` MSB extended), or a numeric list of CSI-RS configuration indices. You can also specify values in a cell array of configurations for each resource.

Zero power CSI-RS resource configuration index lists (TS 36.211 Section 6.10.5.2). Specify each list as a 16-bit bitmap character vector or string scalar (if less than 16 bits, then `'0'` MSB extended), or as a numeric list of CSI-RS configuration indices from TS 36.211 Table 6.10.5.2-1 in the `'4'` CSI reference signal column. Multiple lists can be defined using a cell array of individual lists.

[1]

Note:

1. `CSIRSPeriod` and `ZeroPowerCSIRSPeriod` parameters control the downlink subframes in which the different CSI-RS resources are present. Valid settings include:

• always `'On'`

• always `'Off'`

• scalar subframe configuration index `Icsi-rs` from 0 through 154

• explicit subframe periodicity and offset pair ```[Tcsi-rs Dcsi-rs]```

The subframes containing CSI-RS are located with `NSubframe` and the optional `NFrame` parameters. `NSubframe` can be greater than 10; thus `NSubframe` = 11 is equivalent to setting `NSubframe` to 1 and `NFrame` to 1.

For more information, see TS 36.211 [1], Section 6.10.5.3.

Symbol 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
Symbol style

`'ind'` (default), `'mat'`

Style for returning CSI-RS symbols, specified as one of the following options.

• `'ind'` — returns the CSI-RS symbols as a column vector (default)

• `'mat'` — returns the CSI-RS symbols as a matrix, where each column contains symbols for an individual port and CSI-RS configuration. To form a matrix, a column can contain duplicate entries.

Symbol format

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

Format for the returned symbols, specified as one of the following options.

• `'rsonly'` — returns only defined CSI-RS symbols (default), both zero and non-zero

• `'rs+unused'` — also includes zeros for the resource element (RE) locations that should be unused because they are reserved for CSI-RS on another port.

Note

Returned symbols specify the CSI-RS resource values within an N-by-M-by-antennas array. The number of antennas is `max(CSIRefP)` or if zero power CSI-RS are also defined number of antennas is `max(max(CSIRefP),4)`. For the `'rs+unused'` option, the number of antennas used to define the empty REs (either because they are zero power or they are unused in another port) is `max(max(CSIRefP),CellRefP)`.

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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CSI-RS symbols for transmission in a single subframe on up to eight antenna ports, returned as a column vector or matrix of concatenated CSI-RS symbol sequences for each of the `enb.CSIRefP` ports based on the cell-wide parameter settings. The length of `sym` is the number of resource elements. See lteCSIRS Processing.

Data Types: `double`
Complex Number Support: Yes

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### lteCSIRS Processing

The `lteCSIRS` function supports the creation of multiple non-zero power CSI-RS resources and zero power CSI-RS.

By default the output symbols are returned as a column vector and are ordered as they should be mapped into the resource elements along with lteCSIRSIndices. If, according to the CSI-RS resource subframe configurations and duplex mode, there are no CSI-RS scheduled in the subframe, then the output is empty. Optionally the returned symbols can also include zeros representing the resource elements which should be unused since they are reserved for CSI-RS symbols in one or more of the other ports. On assignment into a populated subframe grid, these zeros create empty resource elements for both Release 8, and Release 10 and 11 compatibility. When multiple non-zero power resources and zero power CSI-RS are output, the zero power CSI-RS symbols are first in the concatenated output, followed by the symbols for the ordered set of CSI-RS resources.

## References

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

## Version History

Introduced in R2014a