R&D: Concatenated Coding Schemes for High Areal Density Bit-Patterned Media Magnetic Recording

IEEE Transactions on Magnetics ( Volume: 54, Issue: 2, Feb. 2018 ) has published an article written by Hidetoshi Saito, Department of Applied Physics, School of Advanced Engineering, Kogakuin University, Tokyo, Japan

Abstract: “This paper proposes a new concatenated error correction coding scheme for 2-D magnetic recording (TDMR). The designed concatenated coding scheme consists of outer codes as binary polar codes and an inner code as non-binary low-density parity-check (LDPC) code. These error-correcting codes (ECCs) are considered to achieve large coding gains with small bandwidth expansion in the presence of intersymbol interference and inter-track interference. Polar codes have attracted much attention as one of the ECCs that provably achieve the optimal symmetric capacity of memoryless channels with an explicit construction and are decoded by the successive-cancellation decoding algorithm, whose computational complexity is comparatively low. Using systematic polar codes, we are able to design proper low-complexity ECCs with run-length-limited constraints for any TDMR schemes based on the selection criterion (which is called channel polarization) for choosing parity and information symbols by the magnitude of the approximately calculated mutual information amount regarding each recorded symbol in a codeword. Concretely, the concatenated coding schemes are designed for four-track and three-track recording, and the block error rate (BER) performances of 2-D partial response equalized signal processing schemes with proposed concatenated ECCs for bit-patterned media recording are evaluated. As a result, it shows that the BER performances of the proposed schemes are superior to that of the conventional scheme using a 1-D high rate binary LDPC code.“