A non-linear LLR approximation for LDPC decoding over impulsive noise channels

The performance of Low-Density Parity-Check codes over symmetric alpha-stable impulsive noise channels is considered in this paper. Due to the lack of closed-form expressions for the probability density functions of almost all the alpha-stable distributions, an efficient non-linear approximation method for channel log-likelihood ratio is presented to achieve high decoding performance covering the range of characteristic exponent from 1 to 2 and avoid the use of complicated numerical integrations. The simulations for both long and short codes show that the parameter selection of the proposed method is not sensitive to the noise level. Even fixed parameter setting for the proposed non-linear approximation can obtain a satisfying decoding performance.