System perspectives for the application of structured LDPC codes to data storage devices

We have three main goals in this paper. First, we will show the equivalences and relationships among some of the well-known classes of structured low density parity check (LDPC) codes. Second, we consider application of these codes to magnetic recording channel. We will make performance comparisons not only with bit-error-rate (BER) metric but also with sector failure rate (SFR) as the comparison dimension. Such a comparison is more meaningful from a system analysis perspective. Finally, we consider the case of these structured LDPC codes concatenated with conventional Reed-Solomon (RS) codes. We believe LDPC codes will not completely replace RS codes in the future storage devices. From this perspective, for LDPC codes to be contenders for future architectures, they will need to work in harmony with the outer RS codes. This implies that we have to take into account the redundancy introduced by the overall coding scheme, that is, RS code in concatenation with LDPC code, to reach meaningful comparisons from a system design perspective.