Soft decoding in optical systems: Turbo product codes vs. LDPC codes

Abstract

We consider the use of two classes of forward error correction (FEC) codes (concatenated codes with interleaver and LDPC codes) in optical communication systems. Soft iterative decoding is applied to both class of codes. In the simulations, the optimum log-likelihood ratio to be provided to the soft decoder in the optical channel environment is evaluated. Simulation results refer to practical turbo-product and LDPC codes, and encompass the effect of quantization on the log-likelihood ratio. The results show that LDPC codes give better results than turbo product codes. Moreover, they turn out to be more robust to quantization. © 2005 Springer Science + Business Media, Inc. Boston.