LDPC Parity Check Matrix

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This block creates a FEC LDPC Parity Check Matrix variable.

This variable can be used by:

 1) LDPC Encoder Definition (via Parity Check) block
 2) LDPC Bit Flip Decoder Definition block

The format of alist files is described at: [1]

The specific format of this parity check matrix is described by Richardson and Urbanke in Appendix A of their book: Modern Coding Theory (ISBN 978-0-521-85229-6).

As an example, see the file [2]], which is used by the FEC example flowgraph [3].

There is a small library of encoding-ready alist files at [4].

To convert a parity check matrix to the appropriate format required for this encoder, use the python functions in [5].


Name of an alist file to use.
A property of the matrix being used. For alist files distributed with GNU Radio, this value is specified in the alist filename. The gap is found during the matrix preprocessing algorithm. It is equal to the number of rows in submatrices E, C and D.

Example Flowgraph

This flowgraph can be found at [6]

Fecapi ldpc encoders fg.png

Source Files

C++ files
Header files
Public header files
Block definition