ltePSCCHDRS
PSCCH demodulation reference signal
Description
[
returns a 24-by-1 complex column vector sequence containing PSCCH demodulation
reference signal (DM-RS) values and an associated information structure. For more
information, see PSCCH Demodulation Reference Signal Processing.seq
,info
]
= ltePSCCHDRS
[
returns a vector of DM-RS values for either D2D or V2X sidelink given the specified
UE settings structure. For more information, see PSCCH Demodulation Reference Signal Processing.seq
,info
]
= ltePSCCHDRS(ue
)
Examples
Generate PSCCH DM-RS Sequence
Generate a PSCCH DM-RS sequence associated with both DM-RS SC-FDMA symbols in a subframe. Plot the constellation of the sequence, which is QPSK modulated.
[pscchDrsSeq,info] = ltePSCCHDRS;
plot(pscchDrsSeq,'o')
Generate PSCCH DM-RS sequence for V2X sidelink
Generate the PSCCH DM-RS sequence associated with the four DM-RS SC-FDMA symbols of a PRB pair for a PSCCH transmission and V2X sidelink.
Create a user equipment settings structure for the V2X sidelink mode with PRB set indices of 0 and 1 and a zero cyclic shift.
ue = struct('SidelinkMode','V2X'); ue.PRBSet = [0 1]'; ue.CyclicShift = 0;
Generate a PSCCH DM-RS sequence associated with both DM-RS SC-FDMA symbols in a subframe. The output sequence is a 96-length vector to be mapped onto the 24 subcarriers in each of the pair of DM-RS SC-FDMA symbols per slot for two consecutive resource blocks.
[pscchDrsSeq,info] = ltePSCCHDRS(ue); size(pscchDrsSeq)
ans = 1×2
96 1
Input Arguments
ue
— User equipment settings
structure
User equipment settings, specified as a parameter structure containing these fields:
SidelinkMode
— Sidelink mode
'D2D'
(default) | 'V2X'
| optional
Sidelink mode, specified as 'D2D'
or
'V2X'
.
Data Types: char
| string
PRBSet
— Zero-based physical resource block index
integer | integer column vector | two-column integer matrix
Zero-based physical resource block (PRB) index, specified as an integer, an integer column vector, or a two-column integer matrix.
For D2D sidelink, the PSCCH is intended to be transmitted in a single PRB in a subframe and
therefore, specifying PRBSet
as a scalar PRB index is recommended.
For V2X sidelink, the PSCCH is intended to be transmitted in a pair of consecutive PRB
in a subframe, therefore PRBSet
must be a column vector containing
two consecutive indices. However, for a more general nonstandard multi-PRB allocation,
PRBSet
can be a set of indices specified as an integer column
vector or as a two-column integer matrix corresponding to slot-wise resource allocations
for PSCCH.
Data Types: double
CyclicShift
— Cyclic shift for DM-RS
0 (default) | 3
| 6
| 9
Cyclic shift for DM-RS, specified as 0
,
3
, 6
or
9
. The function uses this input only for
V2X sidelink.
Data Types: double
Data Types: struct
Output Arguments
seq
— PSCCH DM-RS values
column vector
PSCCH DM-RS values, returned as a complex column vector. For more information, see PSCCH Demodulation Reference Signal Processing.
Data Types: double
Complex Number Support: Yes
info
— PSCCH DM-RS information
structure
PSCCH DM-RS information about the intermediate variables used to create the DM-RS, returned as a parameter structure containing these fields:
SeqGroup
— Base sequence group number for each slot
two-column vector
Base sequence group number for each slot, returned as a two-column vector. (u)
SeqIdx
— Base sequence number for each slot
two-column vector
Base sequence number for each slot, returned as a two-column vector. (v)
RootSeq
— Root Zadoff-Chu sequence index for each slot
two-column vector
Root Zadoff-Chu sequence index for each slot, returned as a two-column vector. (q)
NCS
— Cyclic shift values for each slot
two-column vector
Cyclic shift values for each slot, returned as a two-column vector. ()
NZC
— Zadoff-Chu sequence length
integer
Zadoff-Chu sequence length, returned as an integer. ()
OrthSeq
— Orthogonal cover value for each slot
matrix
Orthogonal cover value for each slot, returned as a matrix. ()
Data Types: struct
More About
PSCCH Demodulation Reference Signal Processing
The PSCCH demodulation reference signal (DM-RS) sequence is transmitted
alongside the ltePSCCH
values using the two SC-FDMA symbols
allocated to DM-RS in a PSCCH subframe. By default, the output vector is the repetition of
a 12-element sequence and specified in TS 36.211, Section 9.8. The output vector is mapped
onto the 12 subcarriers of the DM-RS SC-FDMA symbol in each slot of the single PSCCH
physical resource block (PRB) transmission on antenna port 1000. For a V2X configured PSCCH,
the output will be a 96-by-1 vector to be mapped onto the 24 subcarriers in each of the pair
of DRS SC-FDMA symbols per slot for two consecutive resource blocks.
The single-PRB PSCCH DM-RS is transmitted using a short base
QPSK reference sequence instead of the Zadoff-Chu sequence that is
normally used for reference signals. Because the Zadoff-Chu sequence
is not used, the RootSeq
and NZC
fields
are set to –1 in the info
structure returned
by ltePSCCHDRS
.
PSCCH Demodulation Reference Signal Indexing
Use the indexing function, ltePSCCHDRSIndices
, and the corresponding
sequence function, ltePSCCHDRS
,
to populate the resource grid for any PSCCH subframe. The PSCCH DM-RS
is transmitted in the available SC-FDMA symbols in a PSCCH subframe,
using a single layer on antenna port 1000.
The indices are ordered as the PSCCH DM-RS QPSK modulation symbols
should be, applying frequency-first mapping. One-based linear indexing
is the default return format but you can also generate alternative
indexing formats by using the opts
input.
The resource elements in the last SC-FDMA symbol within a subframe are counted in the mapping process but should not be transmitted. The sidelink-specific SC-FDMA modulation creates the last symbol, which serves as a guard symbol.
For D2D sidelink, in zero-based indexing, the SC-FDMA symbol indices used are {3,10} for
normal cyclic prefix and {2,8} for extended cyclic prefix. The same symbols are used by the
ltePUSCHDRSIndices
function. For V2X sidelink, there are four DM-RS SC-FDMA
symbols with indices {2,5,8,11}, defined for normal cyclic prefix only.
Note
The indicated symbol indices are based on TS 36.211, Section 9.8. However to align with the LTE Toolbox™ subframe orientation, these indices are expanded from symbol index per slot to symbol index per subframe.
For more information on mapping symbols to the resource element grid, see Resource Grid Indexing.
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 R2016b
See Also
ltePSCCHDRSIndices
| ltePSCCH
| ltePSCCHDecode
| ltePSCCHIndices
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