Learning Algorithms for Error Correction

Published in Masters thesis, 2018

Recommended citation: L. Lugosch, “Learning algorithms for error correction”, Masters thesis, McGill University, 2018. http://lorenlugosch.github.io/Masters_Thesis.pdf

Channel coding enables reliable communication over unreliable, noisy channels: by encoding messages with redundancy, it is possible to decode the messages in such a way that errors introduced by the channel are corrected. Modern channel codes achieve very low error rates at long block lengths, but long blocks are often not acceptable for low-latency applications. While there exist short block codes with excellent error-correction performance when decoded optimally, designing practical, low-complexity decoding algorithms that can achieve close-to-optimal results for short codes is still an open problem. In this thesis, we explore an approach to decoding short block codes in which the decoder is recast as a machine learning algorithm. After providing the background concepts on errorcorrecting codes and machine learning, we review the literature on learning algorithms for error correction, with a special emphasis on the recently introduced “neural belief propagation” algorithm. We then describe a set of modifications to neural belief propagation which improve its performance and reduce its implementation complexity. We also propose a new syndrome-based output layer for neural error-correcting decoders which takes the code structure into account during training to yield decoders with lower frame error rate. Finally, we suggest some future work.