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To meet the demand for storing large amounts of data, there has been a stronger focus on increasing the recording density of a hard disk drive (HDD). While conventional HDD suffers from thermal effect and superparamagnetic limit, bit-patterned media recording (BPMR) has the potential to resolve these problems and is capable of increasing areal density (AD) beyond 1 terabit per square inch. To increase the AD of BPMR, the distance between islands in both the down- and cross-track directions must be reduced. Consequently, the decreased bit period and track pitch induce more intersymbol interference (ISI) and intertrack interference (ITI), which degrade the bit error rate (BER) performance. In this study, extrinsic information obtained from a multilayer perceptron (MLP) equalizer is used as a priori information in a partial response maximum-likelihood (PRML) detector to improve the detection performance of BPMR. The proposed detection scheme shows better performance compared to both the MLP equalizer and conventional PRML alone. In addition, it was found that the proposed detector provides improved performance when track misregistration (TMR) occurs. [ABSTRACT FROM AUTHOR]

In a bit-patterned media recording (BPMR) system, reducing the spacing between adjacent bit islands in the down- and cross-track directions increases areal density; however, two-dimensional (2-D) interference comprising intersymbol and intertrack interferences degrades the system performance. To mitigate error patterns that increase the 2-D interference in BPMRs, 2-D modulation coding schemes have been proposed. In this letter, we present a modulation code and its decoding using a multilayer perceptron (MLP) for BPMRs. Modulation decoding using an MLP can achieve significantly better performance than that using the minimum Euclidean distance, which is generally used to decode received modulated data. Similarly, when comparing the system performance at the same user density, modulation decoding using an MLP at 3 Tb/in2 shows better performance than an uncoded system (partial response maximum-likelihood detector) at 2 Tb/in2. [ABSTRACT FROM AUTHOR]

Because of the exponential increase in internal and external information, we need to handle the enormous amount of data. However, there is a limit to data storage on hard disk drives because of a super-paramagnetism phenomenon which prevents the formation of a high areal density (AD). Accordingly, research about bit-patterned media recording (BPMR) that stores one bit in a single magnetic island is actively in progress. BPMR can increase stored data quantities by adjusting the distance between islands. However, inter-symbol interference and inter-track interference cause problems that degrade performance due to bit period and small track pitch, respectively. Moreover, the island pattern also affects the performance because depending on the pattern, 2-D interference is changed. In this paper, we experiment to find the case that minimizes the bit error ratio in the same AD with various distances between the islands, and compares the performance in the staggered and rectangular patterns. [ABSTRACT FROM AUTHOR]

Bit-patterned media recording (BPMR) has been developed into a technology for the next generation of hard disc drives, which can push area density beyond 1 Tb/in2 for satisfying the ever increasing demand of storing massive amounts of data. One of the major challenges in BPMR systems is 2-D interference that is regarded as a gist of degrading the system performance. From a signal processing viewpoint, 2-D optimal detection schemes are very complicated for 2-D interference channels. In this paper, we propose a twin iterative detection scheme based on 1-D detectors and decoders in order to reduce the complexity. The performance of the proposed scheme is compared to that of a conventional simplified 2-D iterative detection scheme, and the results indicate that the proposed model is better by approximately 1 dB under the effect of 10% track misregistration. [ABSTRACT FROM AUTHOR]

Because of the explosion in data growth, the requirement for high-density storage systems has increased. Bit-patterned media recording (BPMR) is a candidate for the next-generation magnetic recording systems, and its many advantages facilitate the achievement of recording densities of 1 Tb/in2 and beyond. In BPMR, each information bit is represented by a magnetic island; however, due to the small spacings between the along- and across-track islands that are for the achievement of a high areal density, severe extents of the inter-symbol interference and inter-track interference appear. These error factors degrade the system performance of the recording system. In this paper, an iterative channel detection scheme with a low-density parity check (LDPC) product code for which the extrinsic information between the soft output Viterbi algorithm and the LDPC product code is used for the BPMR is proposed. For the improvement of the BPMR performance, the modified extrinsic information data are exploited. [ABSTRACT FROM AUTHOR]

This paper presents a scheme that utilizes soft feedback information obtained from a decoder to eliminate detrimental interference in bit-patterned media recording (BPMR) systems. BPMR is a promising technology that can increase the storage area density of magnetic storage systems, but one of the main challenges is to overcome 2-D spatial interference. The performance of the proposed scheme is compared with that of a conventional iterative detection scheme, and the results indicate that the proposed model is better by approximately 1 dB at 20% track misregistration. In particular, the performance of the system is quite superior, allowing the design of systems with higher area densities. [ABSTRACT FROM AUTHOR]

Bit patterned media aims at high density recording of more than 10 Tb per square inch, but a burst error mostly occurred by media defects, and data write failure can be a serious problem. However, if the burst errors are compensated by erasure decoding, the performance of low-density parity check (LDPC) code, which is a strong candidate for the error correcting code for storage systems, can be improved. In this paper, we propose an iterative LDPC–LDPC product code and show that it performs better than a simple LDPC–LDPC product code when there are only random errors and both random and burst errors. [ABSTRACT FROM AUTHOR]