ECC-less LDPC coding for magnetic recording channels

Summary form only given. Low-density parity check (LDPC) codes are receiving considerable attention as a next-generation coding technique for magnetic recording channels, because they show a 5 dB gain over the conventional PRML method. The gain, however, reduces to 1-1.5 dB if the code is combined with an error correcting code (ECC). After the LDPC code, the ECC is not effective in the sense that its gain is less than the rate loss. In fact, we found that ECC-less LDPC codes perform better than LDPC codes with ECC. However, it is still difficult to avoid use of the ECC since the iterative decoder is unable to correct erasures caused by thermal asperity (TA) or media defects. This paper presents a method of erasure compensation for the iterative decoder. The method enables the use of ECC-less LDPC codes, which leads to better performance than using LDPC codes with ECC.