An Iterative Two-Head Two-Track Detection Method for Staggered Bit-Patterned Magnetic Recording Systems

A Novel ITI Suppression Technique for Coded Dual-Track Dual-Head Bit-Patterned Magnetic Recording Systems

“…Similarly, to subside the ITI embedded in the 2nd readback signal, we subtract the weighted version of the 1st readback signal from the 2nd readback signal. This process is similar to [18], [20],…”

“…This section explains how the proposed ITI suppression technique operates and briefly summarizes how to design the 2D target and its compatible 1D equalizer. In [20], the ITI suppression technique for the coded DTDH BPMR channel with a staggered array island medium was presented, which employed the hard decision from the LDPC decoder to estimate the ITI signal. To improve its performance further, this paper proposes to utilize the soft information from the LDPC decoder to approximate the ITI signal for the BPMR channel with a regular array island medium [22].…”

“…Nevertheless, with the proposed technique, the refined readback signals in (8) and (9) contain only the one-side ITI effect. Thus, we can utilize the 2 × 3 target so as to decrease the detector's complexity, which has only 16 states with 4 incoming/outgoing branches [20]. Consequently, this section briefly summarizes how to design the 2 × 3 target and its compatible 1D equalizer based on an MMSE approach [25].…”

“…Nowadays, a modern signal processing technique for magnetic recording systems usually utilizes a multi-track multihead concept that performs together with the turbo decoding process [19] to boost the system performance [14], [20], [21]. For instance, Koonkarnkhai et al [20] introduced an iterative 2H2T detection method for a staggered BPMR system to lessen the ITI effect. To do so, at the first iteration, we subtracted the weighted readback signal obtained from the adjacent tracks (served as an estimated ITI signal) from the target readback signal, before passing the refined readback signal to the turbo decoder.…”

“…Hence, the log-likelihood ratios (LLRs) of the coded bits obtained from the low-density parity-check (LDPC) decoder [23] are utilized to produce the weighted readback signals before subtracting them from the target readback signals. The proposed system can provide better bit-error rate (BER) performance if compared to the DTDH system with hard ITI suppression technique [20] and the conventional system for all ADs, particularly when the recording system severely encounters both media noise and TMR.…”