Physical downlink control channel
The function returns a matrix (
complex modulation symbols generated by the set of Physical Downlink
Control Channels (PDCCH) in a subframe. The channel processing includes
the stages of scrambling, QPSK modulation, layer mapping and precoding,
followed by REG interleaving and cyclic shifting. For a given input
bit vector (typically the PDCCH multiplex), the output matrix
the QPSK symbols in column-wise antenna form. Any input bits with
value < 0 are turned into
<NIL> ('0') symbols.
The optional structure
info returns control resourcing
information about the output symbols (see
Generate complex modulated symbols for the PDCCH. The PDCCH symbols are QPSK modulated. Each QPSK symbol represents two bits.
Create a cell-wide configuration structure, initialized for RMC R.0. Retrieve the PDCCH information.
enb = lteRMCDL('R.0'); pdcchInfo = ltePDCCHInfo(enb)
pdcchInfo = struct with fields: NREG: 113 NRE: 452 NCCE: 12 NREGUsed: 108 NREUsed: 432 MTot: 904 NSymbols: 3
pdcch.MTot indicates the maximum number of input bits that can be transmitted on the PDCCH.
Generate a codeword that is
MTot bits long. Using the codeword, generate PDCCH symbols.
cw = randi([0,1],pdcchInfo.MTot,1); [pdcchSym,info] = ltePDCCH(enb,cw); numCodewordBits = length(cw)
numCodewordBits = 904
numPDCCHSymbols = length(pdcchSym)
numPDCCHSymbols = 452
Since there are two bits per symbol, the number of output PDCCH symbols is half length of the codeword bit stream.
enb— Cell-wide settings
Cell-wide settings, specified as a scalar structure.
the following fields.
|Parameter Field||Required or Optional||Values||Description|
1, 2, 4
Number of cell-specific reference signal (CRS) antenna ports
Integer from 0 to 503
Physical layer cell identity
Integer greater than 0
Nonnegative scalar integer (6,...,110)
Number of downlink resource blocks. ()
Cyclic prefix length
1, 2, or 3
Control format indicator value
PHICH group multiplier
Duplexing mode, specified as:
|The following field is required
0, 1 (default), 2, 3, 4, 5, 6
cw— Input bit vector
Input bit vector that is 32 elements in length, specified as
a vector. If
length(cw) < 32,
padded with zeros before channel processing. If
> 32, only the first 32 elements are used.
cw = lteCFI(struct('CFI',1));
NREG— Resource element groups (REGs) assigned to PDCCH
Resource element groups (REGs) assigned to PDCCH.
CCEGAINS— Vector that controls the QPSK symbol gains on a per CCE basis
Vector that controls the QPSK symbol gains on a per CCE basis. Each
CCE (Control Channel Element) is a group of 36 QPSK symbols (72 bits)
and is the minimum unit that a single coded DCI can be mapped to.
The number of complete CCE, NCCE = floor(NREG/9), is available via
NCCE field in
CCEGAINS acts as a linear multiplier
to all 36 symbols generated from the associated block of 72 input
CCEGAINS does not cover all the
NCCE, then the uncovered CCE receives
zero power. All symbols are interleaved before they are output.
Complex Number Support: Yes
sym— PDCCH modulation symbols
PDCCH modulation symbols, given the input bit vector
returned as a
NRE is the number of QPSK symbols per antenna
CellRefP is the number of TX antenna ports.
to the number of control region resource elements assigned to the
PDCCH given the structure
Complex Number Support: Yes
info— Information for various PDCCH resourcing quantities
Information for various PDCCH resourcing quantities, returned
as a structure. It contains fields including
MTot is the maximum number of input bits
that can be transmitted on the
NRE symbols (
NRE = 8×
length(cw)<MTot, the input is padded with
which translate to zero valued symbols. Any elements of input vector
< 0 are also treated as
only the first
MTot bits are used.