LDPC Parity Check Matrix

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].

Parameters

File

Name of an alist file to use.

Gap

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

Insert description of flowgraph here, then show a screenshot of the flowgraph and the output if there is an interesting GUI. Currently we have no standard method of uploading the actual flowgraph to the wiki or git repo, unfortunately. The plan is to have an example flowgraph showing how the block might be used, for every block, and the flowgraphs will live in the git repo.

Source Files

C++ files

[6]

Header files

[7]

Public header files

[8]

Block definition

[9]