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

Select the encoder type.

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.