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.

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

Examples

Create CSI-RS Symbols and Combine with Resource Grid

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

enb — eNodeB cell-wide settings

structure

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

Parameter Field	Required or Optional	Values	Description
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	Uplink–downlink configuration
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: 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.

opts — Symbol generation options

character vector | cell array of character vectors | string array

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):

Option	Values	Description
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

sym — CSI-RS symbols

column vector (default) | matrix

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

More About

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.