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

Round 1

Reviewer 1 Report

The paper investigates the problem of equalization for bit-patterned media recording systems. A modified Viterbi algorithm combined with feedback is proposed. The proposed algorithm achieves a gain compared with the modified Viterbi algorithm from [12]. However, reference [12] is relatively old. There exist newer papers that combine the modified Viterbi algorithm with other 2D equalization techniques, e.g. reference [13]. Hence, the presented results are not completely convincing.  

The references are not comprehensive. There are other papers that use soft decision feedback algorithm for such channels, e.g.

Zheng, X. Ma, Y. L. Guan, K. Cai and K. S. Chan, "Low-Complexity Iterative Row-Column Soft Decision Feedback Algorithm for 2-D Inter-Symbol Interference Channel Detection With Gaussian Approximation," in IEEE Transactions on Magnetics, vol. 49, no. 8, pp. 4768-4773, Aug. 2013, doi: 10.1109/TMAG.2013.2242333.

This work should be discussed.

Moreover, the presentation of the study should be improved.

• The term “magnetic storage“ should be mentioned somewhere in the abstract.
• Lines 64-69 should be moved to Section 2.
• The notation is not always clear. Why do you use G in (1) and C in (2) to denote the channel?
• You should use subscripts to denote the two matrices G and the two target signals in Fig. 7.
• I think you should use different line types for signals and target signals in Fig. 7.
• The system model is complex. Hence, at the beginning of Sec. 3 there should be a textual explanation of the system model. In particular, the concept of the GPR target should be explained.
• The conclusions are very brief. There should be more discussion.

Author Response

Please see the attachment

Author Response File: Author Response.docx

Reviewer 2 Report

This paper is focused on an important topic, related with media recordings, data storage, and occurring intersymbol interference. Authors propose their own solution, based on the well-known Viterbi algorithm.

Authors adequately point out that in the past the gross amount of data (and digital information) was generated by industrial applications. Nowadays, thanks to the widespread of mobile devices, social networks and wireless interfaces, data is being generated at a much faster rate. Currently, with the growing interest in IoT technology, this trend will continue to grow even faster.

The manuscript provides a good introduction to data storage media, including pros and cons of different recording technologies. The discussed mathematical formulas and equations seem properly justified. Utilized symbols are written in italics (or bold) in order to distinguish them from plain text. Displayed graphs and plots are clear and understandable. However, some modifications could be done in order to make them more readable.

The second (research) part of the manuscript describes an undeniably wide measurement (simulation) campaign. The Author’s commitment and dedication is clearly visible. After presenting such a broad set of results, the length of the Conclusions chapter is surprising. It is necessary to expand this part and draw conclusions based on the research carried out.

In my opinion, the Authors could provide some information about utilized software, simulation environment, libraries, etc. Additionally, maybe mention something about the computational complexity (e.g. compared to “traditional” methods). If the whole laboratory stand was custom-build (and/or patent-related), provide at least some basic info. This would be interesting for many potential readers.

 

Overall, this paper is concise, well-organized and properly formatted. The English grammar and spelling is correct, it is pleasant to read. In my opinion, this manuscript requires only a minor revision before it can be published.

 

Suggestions:

• Title – consider writing [Two-Dimensional] with a capital [D] – just like [3-Way] and [Bit-Patterned].
• Personally, I tend to write [Internet] with a capital [I], as it is the name of a technology, just like [Bluetooth].
• Double-check whether all matrixes have the same size, including utilized fonts, etc.
• In my opinion all figures could be bigger in size, with larger fonts – this would make them easier to read; currently, they seem to small.
• Double-check the whole manuscript for additional (double) space signs.
• Figure 6 should appear in the main body of the manuscript after a portion of text, and not just at the beginning of sub-chapter 2.3.
• Undisputably, the Conclusions chapter has to be extended.

Author Response

Please see the attachment

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The authors have addressed all my comments. I have no further questions.