lteDMRS
UE-specific demodulation reference signals
Description
returns
the downlink UE-specific demodulation reference signal (DM-RS) symbols
for transmission in a single subframe, given structures containing
the cell-wide settings, and the PDSCH configuration settings. For
more information, see DM-RS Associated with PDSCH.sym
= lteDMRS(enb
,chs
)
Examples
Map PDSCH DM-RS Symbols to Grid
Map DM-RS symbols for 4 layers onto an 8 antenna grid.
Initialize cell-wide settings for RMC 'R.1'
(10 MHz bandwidth, 1 RB allocation) and change to Release 10 transmission ('Port7-14'
). Use enb.PDSCH
for the channel configuration structure input. Generate and map DM-RS without clearing the REs that should not be mapped because of the DM-RS on other ports.
enb = lteRMCDL('R.1'); enb.PDSCH.TxScheme = 'Port7-14'; enb.PDSCH.NLayers = 4; ntxants = 8; enb.PDSCH.W = lteCSICodebook(enb.PDSCH.NLayers,ntxants,[0 0]).'; subframe = ones(lteResourceGridSize(enb,ntxants)); enb.PDSCH.NTxAnts = size(enb.PDSCH.W,2); dmrsInd = lteDMRSIndices(enb,enb.PDSCH); dmrs = lteDMRS(enb,enb.PDSCH); subframe(dmrsInd) = dmrs;
View the size of the output symbols, indices, and the Release 10 transmission subframe
.
size(dmrs)
ans = 1×2
192 1
size(dmrsInd)
ans = 1×2
192 1
size(subframe)
ans = 1×3
600 14 8
Map Non-Precoded DM-RS Symbols to Grid
Map non-precoded DM-RS symbols onto an 4 layer grid, and clear the REs which should not be used because of the DM-RS of other ports.
Initialize cellwide settings for RMC 'R.1'
(10 MHz bandwidth, 1 RB allocation) and change to Release 10 transmission ('Port7-14'
). Generate and map DM-RS clearing the REs that should not be used because of the DM-RS on other ports.
enb = lteRMCDL('R.1'); enb.PDSCH.TxScheme = 'Port7-14'; enb.PDSCH.NLayers = 4; subframe = ones(lteResourceGridSize(enb,enb.PDSCH.NLayers)); dmrsInd = lteDMRSIndices(enb,enb.PDSCH,'rs+unused'); dmrs = lteDMRS(enb,enb.PDSCH,'rs+unused'); subframe(dmrsInd) = dmrs; size(dmrs)
ans = 1×2
96 1
size(dmrsInd)
ans = 1×2
96 1
size(subframe)
ans = 1×3
600 14 4
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 () |
NCellID | Required | Integer from 0 to 503 | Physical layer cell identity |
NSubframe | Required | 0 (default), nonnegative scalar integer | Subframe number |
CyclicPrefix | Optional |
| Cyclic prefix length |
DuplexMode | Optional |
| Duplexing mode, specified as either:
|
The following parameters are dependent upon the condition that | |||
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) |
chs
— PDSCH-specific channel transmission configuration
structure
PDSCH-specific channel transmission configuration, specified as a structure that can contain these parameter fields.
Parameter Field | Required or Optional | Values | Description | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
PRBSet | Required | Integer column vector or two-column matrix | Zero-based physical resource block (PRB) indices corresponding
to the slot wise resource allocations for this PDSCH.
PRBSet varies per subframe for the RMCs | ||||||||||
TxScheme | Optional |
| DM-RS-specific transmission scheme, specified as one of the following options.
| ||||||||||
NLayers | Optional | 1 (default), 2, 3, 4, 5, 6, 7, 8 | Number of transmission layers. | ||||||||||
W | Optional | Numeric matrix, |
| ||||||||||
The following parameter is applicable when | |||||||||||||
NSCID | Optional | 0 (default), 1 | Scrambling identity (ID) | ||||||||||
The following parameter is applicable when | |||||||||||||
RNTI | Required | 0 (default), scalar integer | Radio network temporary identifier (RNTI) value (16 bits) |
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. Values for opts
when
specified as a character vector include (use double quotes for string):
Option | Values | Description |
---|---|---|
Symbol style |
| Style for returning DM-RS symbols, specified as one of the following options.
NRE is the number of resource elements. |
Symbol format |
| Format for returning DM-RS symbols, specified as one of the following options.
|
Example: {'ind','rs+unused'}
, returns the
DM-RS symbols as a column vector that includes zeros for the RE locations
that should be unused because of DM-RS transmission on another port
or layer.
Data Types: char
| string
| cell
Output Arguments
sym
— DM-RS symbol sequences
NRE-by-1
numeric column vector (default) | numeric matrix
DM-RS symbol sequences, returned as an NRE-by-1
numeric column vector, or a numeric matrix. NRE is
the number of resource elements. The opts
input
offers alternative output styles or formats.
sym
contains the non-precoded or precoded
DM-RS symbol sequences concatenated for all the layers, or the transmit
antennas for the transmission scheme. The symbols are always ordered
as they should be mapped using lteDMRSIndices
into
an M-by-N-by-P array
representing the subframe grid across either the non-precoded PDSCH
layers or precoded transmit antennas. M is the
number of subcarriers, N is the number of symbols,
and P is the number of layers, or antennas.
Since precoding projects the DM-RS in each PDSCH layer onto
all NTxAnts
transmit antennas, the output contains
the concatenation of all DM-RS across all layers, which are then duplicated
in all chs
.
NTxAnts
planes
of the 3-D grid.
The output is returned empty unless
chs
.
TxScheme
is set to one of the schemes related to DM-RS, specifically'Port5'
,'Port7-8'
,'Port8'
, or'Port7-14'
.If the
chs
.
TxScheme
is single port,chs
.
NLayers
= 1 implicitly.The output does not include any elements allocated to PBCH, PSS, and SSS. If the subframe contains no DM-RS, an empty vector is returned.
If the precoding matrix, field
chs
.
W, is not present or is empty, the output is returned containing only the concatenated non-precoded DM-RS symbols for theNLayers
ports.Otherwise, the output,
sym
, contains all DM-RS symbol values after they are precoded using theNLayers
-by-NTxAnts
beamforming matrix, W, ontoNTxAnts
transmit antennas. The symbols are ordered by:The concatenation of DM-RS symbols per layer/port if not precoded
The projected layers per transmit antenna if precoded.
For more information, see DM-RS Associated with PDSCH.
Data Types: double
Complex Number Support: Yes
More About
DM-RS Associated with PDSCH
As specified in TS 36.211, Section 6.10.3, UE-specific demodulation reference signal (DM-RS) associated with the physical downlink shared channel (PDSCH):
are transmitted in a single subframe on antenna ports p=5, p=7, p=8, or p=7, 8,..., (
NLayers
+6).are present and are a valid reference for PDSCH demodulation only if the PDSCH transmission is associated with the corresponding antenna port according to TS 36.213, Section 7.1.
are transmitted only on the physical resource blocks upon which the corresponding PDSCH is mapped.
These DM-RS are for use with Release 8, 9, and 10 non-codebook-based PDSCH transmission schemes.
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.
[2] 3GPP TS 36.213. “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures.” 3rd Generation Partnership Project; Technical Specification Group Radio Access Network. URL: https://www.3gpp.org.
Version History
Introduced in R2014a
See Also
lteDMRSIndices
| lteCellRS
| lteEPDCCHDMRS
| ltePRS
| lteCSIRS
| ltePDSCH
| ltePRBS
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