Updated June 22,2007

Finally, I completed all four LDPC MATLAB codes I needed for my thesis. I am studying a class of error correcting codes called low-density parity-check codes or LDPC codes. It’s one of the best codes which was developed lately and continues to attract a lot of researches.

A what???

Error correcting codes are important in communications. Imagine sending a text message to someone like “I LOVE YOU”. Due to noise present, the text message gets corrupted and its possible that the text message becomes a different set of unrecognizable characters. This is where a good error correcting code comes in. Once you receive the message, it tries to detect an error and correct it as the same time. This is a neat solution since it saves you from texting again and again until the correct message is received. Of course, this is just a simple and exaggerated example. But error correcting codes made a lot of things we enjoy today possible. Cellphones, satellites, cable, computers, mp3 players and a lot more.

I’m sharing my codes to those who are also interested in learning about LDPC codes. My thesis is devoted to studying the hard-decision bit flipping algorithms and I will be implementing it into a hardware. There are 4 types of algorithm I’m trying to study. Bit Flipping algorithms are the simplest decoding schemes available for LDPC codes. They provide a good trade-off between complexity and performance. These codes are good for those who what to start learnin about LDPC codes.

Here’s a list of the algorithms:

1. Standard Bit Flipping (BF) Algorithm by R Gallager
2. Weighted Bit Flipping (WBF) Algorithm by Y Kou, S Lin, M Fossorier
3. Modified Weighted Bit Flipping (IWBF) Algorithm by J Zhang, M Fossorier
4. Implementation-efficient Reliability Ratio based Weighted Bit-Flipping (IRRWBF) Algorithm by CH Lee and W Wolf

I placed a short instruction on how to use the code with the zip file as well as a few more links.

If you want to know more about LDPC codes, there are a lot of resources in the web. It took me almost six months to gather them and help me understand what my thesis will all be about. I hope my codes will help others who want to learn about LDPC shorten the learning curve.

Click here to download the zip file.