Improved Decoding of Low-Density Parity-Check Codes by Reduction of Pseudocodewords

E.I. Papagiannis, A. Ambroze, M. Tomlinson, and M.Z. Ahmed (UK)


Coding and Modulation Techniques, LDPC codes, iterative decoding, pseudocodewords


The paper starts with an analysis of iterative decoding based on an implementation of the Sum-Product algorithm for LDPC codes. It is shown that the iterative decoder performs optimum decoding but in a vector space differ ent than this defined by the codebook. The crucial role of the correlation between the received vector and the pseu docodewords is justified by simulation results. Based on these results we present an algorithm which can deliver sig nificant improvement to the iterative performance of LDPC codes, with relatively low complexity. It is shown that max imum likelihood performance can be achieved for a certain range of codes.

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