1 research outputs found
LDPC Code Density Evolution in the Error Floor Region
This short paper explores density evolution (DE) for low-density parity-check
(LDPC) codes at signal-to-noise-ratios (SNRs) that are significantly above the
decoding threshold. The focus is on the additive white Gaussian noise channel
and LDPC codes in which the variable nodes have regular degree.
Prior work, using DE, produced results in the error floor region which were
asymptotic in the belief-propagation decoder's log-likelihood ratio (LLR)
values. We develop expressions which closely approximate the LLR growth
behavior at moderate LLR magnitudes. We then produce bounds on the mean
extrinsic check-node LLR values required, as a function of SNR, such that the
growth rate of the LLRs exceeds that of a particular trapping set's internal
LLRs such that its error floor contribution may be eliminated. We find that our
predictions for the mean LLRs to be accurate in the error floor region, but the
predictions for the LLR variance to be lacking beyond several initial
iterations.Comment: 5 pages, 2 figure