Joint low-complexity detection and reliability-based BP decoding for non-binary LDPC coded TDMR channels

Bit Patterned media recording (BPMR), heat assisted magnetic recording (HAMR), and shingled writing (SMR) with 2-dimensional (2-D) readback have been explored to further scale magnetic recording areal density over the next decade. However, from a signal processing perspective, all these magnetic recording technologies face a common challenge that is how to efficiently recover recorded data from the readback signals corrupted by inter-symbol interference and inter-track interference. The extension of Viterbi algorithm and BCJR algorithm to the 2D ISI channel has prohibitive complexity for the typical 2-D data size. In [1], the authors proposed an IRCSDFA-GA-BCJR detection algorithm which has an enormous complexity reduction compared with the conventional IRCSDFA and the optimal BCJR. In this paper, an efficient iterative detection and decoding scheme is proposed for Non-binary LDPC (NB-LDPC) codes coded two dimensional magnetic recording (TDMR) channels, in which both the low-complexity IRCSDFA-GA-BCJR detection and the fast convergence BP decoding are employed to improve the performance of 2-D channel detection.