Modulation Code and Multilayer Perceptron Decoding for Bit-Patterned Media Recording

2022

Self Cite

As conventional data storage systems are faced with critical problems such as the superparamagnetic limit, bit-patterned media recording (BPMR) has received significant attention as a promising next-generation magnetic data storage system. However, the reduced spacing between islands at increased areal density causes severe intersymbol and intertrack interference, which degrade BPMR system performance. In this study, we introduce a soft-output detector using multi-layer perceptron to predict reliable information. A received signal is equalized and detected by the MLP detector. The MLP detector provides a well-estimated value by using the binary-cross entropy function as a loss function and the identity function as an activation function for the output layer of the MLP detector. This study investigates the received probability distributions out of the detectors and compares the performance of various versions against a conventional detector. Compared with the conventional detection, the proposed MLP detectors provide a small variance and better BER performance than the conventional detection. Simulations of MLP designs show an advantage over conventional detection. Moreover, the proposed MLP detectors with the demodulator exhibit better BER performance than the conventional detector with the demodulator.

Section: Discussionmentioning

confidence: 99%

Soft-Output Detector Using Multi-Layer Perceptron for Bit-Patterned Media Recording

Jeong

2022

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“…With the same code rate, a rate-5/6 constructive ITI code was designed by Kanjanakunchorn and Warisarn to mitigate ITI [12]. With the flexibility of a neural network, Jeong and Lee proposed a decoding scheme based on a multilayer perceptron for BPMR [13].…”

Section: Introductionmentioning

confidence: 99%

Estimating Interference with a Two-Dimensional Viterbi Algorithm for Bit-Patterned Media Recording

Nguyen

2022

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Bit-patterned media recording (BPMR) is proposed as a candidate for future magnetic data storage to overcome superparamagnetism. The distance between magnetic islands in BPMR must be reduced to increase the areal density (AD). As magnetic islands become closer, two-dimensional (2D) interference is increased, including intersymbol interference (ISI) based on the down-track direction and intertrack interference (ITI) from the cross-track direction. We propose an estimator to predict interference from neighboring (upper and lower) tracks. This estimator exploits the 2D Viterbi algorithm (VA) with reduced states. We removed the interference from the neighboring track and applied a simple 1D VA to detect the received signal. The simulation results show that our model performs better than previously proposed models.

“…Error correction codes and modulation code are two common methods to minimize 2D interference in signal processing. Jeong and Lee [7] proposed the use of modulation code and multilayer perceptron decoding for BPMR to reduce and correct errors due to ITI, respectively. Error-correcting 5/6 modulation code was introduced [8] by Nguyen and Lee to reduce 2D interference and correct errors.…”

Section: Introductionmentioning

confidence: 99%

Modified Viterbi Algorithm with Feedback Using a Two-Dimensional 3-Way Generalized Partial Response Target for Bit-Patterned Media Recording Systems

Nguyen

2021

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The ever-increasing demand for data in recent times has led to the emergence of big data and cloud data. The growth in these fields has necessitated that data be centrally stored in data centers. To meet the need for large-scale storage systems at data centers, innovative technology such as bit-pattern media recording (BPMR) has been developed. With BPMR technology, we are able to achieve significant improvements in high areal density (AD) of magnetic data storage systems. However, two-dimensional (2D) interference is a common issue faced with high AD. Intersymbol interference and intertrack interference occur when the distance between the islands is decreased in the down-track and cross-track, respectively. 2D interference adversely affects the performance of BPMR. In this paper, we propose an improved modified Viterbi algorithm (MVA) exploiting a feedback and a new 2D three-way form of a generalized partial response (GPR) target. The proposed MVA with feedback is superior to the previous MVA by eliminating intertrack interference (ITI) more effectively. With the three-way GPR target, the proposed algorithm achieves more stable performance compared to the previous detection algorithms for the track misregistration effect.