The variances of weight and trapping set distributions of non-binary regular low-density parity-check ensembles are derived. Using the second moment method, bounds on the probabilities that a randomly chosen code from the ensemble has its weight and trapping set distributions close to the ensemble averages are obtained.
In this correspondence, we estimate the variance of weight and stopping set distribution of regular low-density parity-check (LDPC) ensembles. Using this estimate and the second moment method we obtain bounds on the probability that a randomly chosen code from regular LDPC ensemble has its weight distribution and stopping set distribution close to respective ensemble averages. We are able to show that a large fraction of total number of codes have their weight and stopping set distribution close to the average