CTH02-4: When Does One Redundant Parity-Check Equation Matter?

We analyze the effect of redundant parity-check equations on the error-floor performance of low-density parity- check (LDPC) codes used over the additive white Gaussian noise (AWGN) channel. Our findings show that a large number of iterative decoding errors in the [2640,1320] Margulis code, confined to point trapping sets in the standard Tanner graph, can be corrected if only one redundant parity-check equation is added to the decoder´s matrix. We also derive an analytic expression relating the number of rows in the parity-check matrix of a code and the parameters of trapping sets in the code´s graph.