BER performance improvement using soft-information flipping method in BPMR systems

Abstract

Inter-track interference (ITI) cancelation is one of the considerable challenges for high areal density (AD) magnetic recording such as bit-patterned magnetic recording (BPMR) technology. In literature, the two-dimensional (2D) modulation codes have been proposed to cancel the ITI effect which can efficiently improve the overall system performance, e.g., a rate5/6 2D modulation code. Although the rate-5/6 modulation code ensures that the readback signal of the center track will not be corrupted by severe ITI; however, both the upper and lower tracks can still be interfered by their sidetracks, which may lead to some errors in decoding process. To improve this shortcoming, we propose a bit-flipping technique that performs together with the rate-5/6 2D modulation code. Here, the relationship between the data encoding constraint and the soft-information obtained from the soft output Viterbi algorithm (SOVA) detector are utilized to be a criterion for flipping the ambiguous data bits. Simulation results indicate that the proposed system is better than the conventional coded system with and without media noise and track mis-registration (TMR) effects.