Correcting Suboptimal Metrics in Iterative Decoders
Paper in proceeding, 2009

In this paper the issue of improving the performance of iterative decoders based on sub-optimal calculation of the messages exchanged during iterations (L-values) is addressed. It is well known in the literature that a simple---yet very effective---way to improve the performance of suboptimal iterative decoders is based on applying a scaling factor to the L-values. In this paper, starting with a theoretical model based on the so-called consistency condition of a random variable, we propose a methodology for correcting the L-values that relies only on the distribution of the soft information exchanged in the iterative process. This methodology gives a clear explanation of why the well-known linear scaling factor provides a very good performance. Additionally, the proposed methodology allows us to avoid the exhaustive search required otherwise. Numerical simulations show that for turbo codes the scaling factors found closely follow the optimum values, which translates to a close-to-optimal BER performance. Moreover, for LDPC codes, the proposed methodology produces a better BER performance compared with the known method in the literature.

Author

Alex Alvarado

Chalmers, Signals and Systems, Communication, Antennas and Optical Networks

Víctor Núñez

Universidad Técnica Federico Santa María

Leszek Szczecinski

INRS-Energy, Materials and Telecommunications

Erik Agrell

Chalmers, Signals and Systems, Communication, Antennas and Optical Networks

IEEE International Conference on Communications

15503607 (ISSN)

5198866
9781424434350 (ISBN)

Areas of Advance

Information and Communication Technology

Subject Categories

Telecommunications

DOI

10.1109/ICC.2009.5198866

ISBN

9781424434350

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