Soft-Decision Algorithm of a Rate-5/6 2D Modulation Code for SHTR in Staggered BPMR Systems

Abstract

With an increasing demand for recording data storage, this paper is interested in magnetic recording in bit-patterned media recording (BPMR) systems. The main problem of BPMR system from track width and bit length decreasing is two-dimensional (2-D) interference, consisting of inter-symbol interference and inter-track interference. One thing that solved this problem is 2-D modulation code of a rate-5/6 for single-head/two-track reading with staggered bit islands. Moreover, we also improve the performance of system by soft decision algorithm and low-density parity-check code because it can do an iterative process. The soft information is created by log-likelihood ratio by using a look-up table of a rate-5/6 through the Boolean logic circuit equation. After that, this soft information is brought to modified one-dimensional (1-D) soft-output Viterbi algorithm detector. At the same code rate of 5/6 and with bit error rate of 10-4, the simulation results show that our proposed scheme at an areal density of 3 Terabit per square inch, is better than system that performs without 2-D modulation code for 2 dB. Moreover, it is also better than previously proposed system that uses hard decisions with 2-D modulation code for 4 dB.