3.2.4.3.1. LDPC Encoder parameters¶
3.2.4.3.1.1. --enc-cw-size, -N
¶
Type: integer Examples: --enc-cw-size 1024
Set the codeword size \(N\).
Note
This parameter value is automatically deduced if the \(H\) parity matrix is given with the --dec-h-path parameter or if the \(G\) generator matrix is given with the --enc-g-path parameter.
3.2.4.3.1.2. --enc-info-bits, -K
¶
Type: integer Examples: --enc-info-bits 512
Set the number of information bits \(K\).
Note
This parameter value is automatically deduced if the \(G\) generator matrix is given with the --enc-g-path parameter.
Note
In some cases, this parameter value can be automatically deduced if the \(H\) parity matrix is given with the --dec-h-path parameter. For regular matrices, \(K = N - M\) where \(N\) and \(M\) are the \(H\) parity matrix dimensions. For non-regular matrices, \(K\) has to be given.
3.2.4.3.1.3. --enc-type
¶
Type: text Allowed values: LDPC
LDPC_H
LDPC_DVBS2
LDPC_IRA
LDPC_QC
AZCW
COSET
USER
Default: AZCW
Examples: --enc-type AZCW
Type of the encoder to use in the simulation.
Description of the allowed values:
Value | Description |
---|---|
LDPC |
Select the generic encoder that encode from a given \(G\) generator matrix (to use with the --enc-g-path parameter). |
LDPC_H |
Build the \(G\) generator matrix from
the given \(H\) parity matrix and then encode with the LDPC method
(to use with the --dec-h-path parameter). |
LDPC_DVBS2 |
Select the optimized encoding process for the DVB-S2 \(H\) matrices (to use with the --enc-cw-size, -N and --enc-info-bits, -K parameters). |
LDPC_IRA |
Select the optimized encoding process for the IRA \(H\) parity matrices (to use with the --dec-h-path parameter). |
LDPC_QC |
Select the optimized encoding process for the QC \(H\) parity matrices (to use with the --dec-h-path parameter). |
AZCW |
See the common --enc-type parameter. |
COSET |
See the common --enc-type parameter. |
USER |
See the common --enc-type parameter. |
Note
The LDPC_DVBS2
encoder type allow the simulation of the
DVB-S2 standard but without the BCH code. All matrices described by
the standard (Tables 5a/5b page 22-23)
are available. You just need to give to the arguments
--enc-info-bits, -K and --enc-cw-size, -N the real
\(K\) and \(N\) LDPC dimensions, respectively.
3.2.4.3.1.4. --enc-g-path
¶
Type: file Rights: read only Examples: --enc-g-path example/path/to/the/G_matrix.alist
Give the path to the \(G\) generator matrix in an AList or QC formated file.
3.2.4.3.1.5. --enc-g-method
¶
Type: text Allowed values: IDENTITY
LU_DEC
Default: IDENTITY
Examples: --enc-g-method IDENTITY
Specify the method used to build the \(G\) generator matrix from the
\(H\) parity matrix when using the LDPC_H
encoder.
Description of the allowed values:
Value | Description |
---|---|
IDENTITY |
Generate an identity on \(H\) to get the parity part. |
LU_DEC |
Generate a hollow \(G\) thanks to the LU decomposition with a guarantee to have the systematic identity. Do not work with irregular matrices. |
LU_DEC
method is faster than IDENTITY
.
3.2.4.3.1.6. --enc-g-save-path
¶
Type: file Rights: write only Examples: --enc-g-save-path example/path/to/the/generated/G_matrix.alist
Set the file path where the \(G\) generator matrix will be saved (AList
file format). To use with the LDPC_H
encoder.
Hint
When running the LDPC_H
encoder, the generation of the \(G\)
matrix can take a non-negligible part of the simulation time. With this
option the \(G\) matrix can be saved once for all and used in the
standard LDPC
decoder after.
Warning
This option is not thread-safe, please run it on a single thread with the --sim-threads, -t parameter.