[Discuss-gnuradio] LDPC GSoC Project Status

[Perez, Tracie R]

Hi all,

I'd just like to share a status of how my LDPC implementation project is going. 
When the summer started, Manu and I made a list of the LDPC-related algorithms 
for encoding, decoding, and parity check matrix construction that we had found 
in our literature review. We then divided them up such that there would be no 
overlap in our efforts. The algorithms that I put on my list were: 

1. Regular and irregular parity check matrix construction functions
2. Generating a code that is optimized for PSK
3. Constructing quasi-cyclic codes which are especially efficient for encoding
4. Performing encoding as described by Richardson & Urbanke in Appendix A of 
'Modern Coding Theory' (manipulating the parity-check matrix into an 
approximate upper triangulation form which reduces complexity during the 
real-time encoding steps)
5. Bit-flip decoding, a hard decision algorithm
6. Min-sum algorithm for decoding

So far, I've written prototype functions for these methods in python, using 
numpy: #1/regular, #4, and #5.

Right now, I'm at the stage where I'm trying to link them all together and 
confirm that the processes perform as expected before moving on to converting 
them to C++. The challenge that I'm facing is that the parity check matrices 
being created by my function are not full rank, and so they don't work with the 
encoding algorithm. I have tried a method to manipulate them into being full 
rank before encoding but it was not successful. This is my top priority right 
now - to be able to have the parity-check matrices that I am creating work with 
the encoding algorithm that I've written up. Then I'd like to finish testing 
the chain of processes before moving on to creating classes that inherit from 
those in the FEC API. 

My GitHub repo is here: https://github.com/tracierenea/GNU-Radio-GSoC2013

Any questions or comments, just let me know. 

Thanks,
Tracie Perez