Factor graphs together with the sum-product algorithm represent a powerful tool for every communication engineer. The fields where they can be applied reach from system modeling to decoding. Many well-known algorithms like the forward-backward algorithm, the Viterbi algorithm, Pearl's belief propagation algorithm, the iterative turbo decoding algorithm, or even some fast Fourier transform algorithms can be regarded as special cases of the sum-product algorithm.

This site has been written as a part of a master's thesis with the title Investigation of Algebraic Codes of Small Block Length using Factor Graphs. It shall give a short overview about the topic Factor Graphs and explain how they can be used for decoding.

The master's thesis investigates different decoders for a extended Hamming code and compares their performance and behavior. The report is here available for download. Furthermore, all realizations that have been examined are implemented in JAVA and can be tested online.

We would be very happy to receive all kinds of comments, ideas, further realizations from you. Please, do not hesitate to contact us! Also, if you have written a paper in this area, it will be a pleasure to add your paper on this site as well.

Written by Stefan M. Moser <stmoser@stud.NOSPAM.ee.ethz.ch> (remove NOSPAM from email-address!)
Last modified: Wed Aug 20 16:03:26 MEST 2003