Non-binary LDPC coded OFDM in impulsive power line channels

In this paper, we propose Irregular Non-Binary Low Density Parity Check (IR-NB-LDPC) codes with Signed Log Fast Fourier Transform (SL-FFT) decoding algorithm to overcome the harsh environment of power-line communication (PLC) channels. Their performance is compared with Irregular Binary LDPC (IR-B-LDPC) codes using the Sum Product algorithm (SPA). The sparse parity check matrix H of both codes are constructed using progressive edge growth (PEG) algorithm with a novel initialization of the apriori log likelihood ratios (LLR) of each decoder to mitigate the highly impulsive noise in PLC channels. Numerical performance results obtained via simulations show that the proposed system at bit error rate of 10^-4 achieves a coding gain of more than 21 dB compared to uncoded system and more than 6 dB compared to IR-B-LDPC codes for the same block length in bits and rates, however, this is accomplished with higher decoding complexity.