Evaluation of Low-Density Parity-Check Codes on Perpendicular Magnetic Recording Model

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Low-density parity-check (LDPC) codes have shown superior error-correcting performance in a variety of data storage system studies, including traditional longitudinal magnetic recording systems. However, perpendicular magnetic recording systems (of increasing interest) exhibit impairments different from longitudinal magnetic recording systems, and thus present new challenges for error-correcting codes. In this effort, we evaluate a structured LDPC code using a perpendicular magnetic recording channel model that includes impairments such as transition noise, nonlinear transition shift, transition percolation, and baseline wander (BLW). The channel model, as well as the LDPC encoder and the decoder are implemented in field-programmable gate array (FPGA) hardware. The LDPC coded system is evaluated down to bit error rate (BER) of 10<formula formulatype="inline"> <tex>$^{-12}$</tex></formula> and frame error rate (FER) of 10<formula formulatype="inline"> <tex>$^{-8}$</tex></formula>. The impact of individual impairments on coding performance is studied separately. The soft output Viterbi algorithm (SOVA) <formula formulatype="inline"><tex>$+$</tex></formula> LDPC system maintains its superior error-correcting performance under the perpendicular recording channel. </para>