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/in $^2$ shows better performance than an uncoded system (partial response maximum likelihood detector) at 2 Tb/in $^2$ .

The first merit of the holographic data storage (HDS) system is its high storage capacity. In practice, it is well known that the total capacity for the storage medium depends on the appropriate ratio of ON and OFF pixels within data pages. Therefore, we propose a modulation code that can control the ratio of ON and OFF pixels. We refer to this code as “tone-controllable code”. In this paper, we introduce the encoding/decoding rules and simulate the bit error rate (BER) performance of the tone-controllable codes having various ratios of ON and OFF pixels.

Bit-patterned media recording (BPMR) is a promising candidate for application in next-generation magnetic recording systems. To achieve a high areal density in BPMR systems, the bit islands are placed close together and their distance is then further reduced. Therefore, two-dimensional (2-D) interference may occur, including intersymbol interference in the down-track and intertrack interference in the across-track. The overall performance of BPMR is mainly limited by the emergence of 2-D interference in the readback signal. With the staggered-array layout, islands along the neighboring track are displaced by a half period from those on the main track. An island on the main track is primarily affected by the closest islands on the neighboring tracks. To overcome this problem, we introduce an error-correcting 5/6 modulation code that matches the structure of staggered-array bit-patterned media. The simulation results show that the system with the proposed modulation code achieves better performance.

With the development of 5G technology, programs are gradually moving to cloud services. This leads to an increasing demand for storage. In the field of high-density data storage, bit-pattern media recording (BPMR) is considered a promising approach, as it can expand the data density to 4 Tb/in². However, in high-density BPMR, bits or magnetic islands are very close to each other, leading to significant intertrack interference (ITI) from the cross-track direction and intersymbol interference (ISI) from the down-track direction. To minimize two-dimensional interference, including ITI and ISI, the serial detector method has been highly effective. However, in this method, the signal at the output of the first decoder is still a hard output. Therefore, we suggest methods to convert the output of the first detector into a soft output. Additionally, we have developed a new form of generalized partial response target to overcome the track mis-registration. The results show that our proposed methods apparently improve bit error rate performance.