The Polar Code Construction Method in Free Space Optical Communication

Round 1

Reviewer 1 Report

July 25, 2022

I find the idea presented in the paper interesting and promising, the Authors drew attention to an important issue, namely  polar code in the Free Space Optical Communication (FSOC), but I have the following comments and concerns:  

A. The Abstract should be rewritten more precisely. It should be pointed out/stressed measurably the effectiveness of the proposed approach. Moreover, the general conclusion which follows from the conducted analysis should be attached.

B. A lack of a reference to noise-related problems in the transmission channels, like in the following papers:

- Kanitscheider, I.; Coen-Cagli, R.; Pouget, A. Origin of information- limiting noise correlations. Proc. Natl. Acad. Sci. USA 2015, 112, e6973–e6982

- Pregowska, A. Signal Fluctuations and the Information Transmission Rates in Binary Communication Channels. Entropy 2021, 23, 92

- Zhang, M.L.; Qu, H.; Xie, X.R.; Kurths, J. Supervised learning in spiking, neural networks with noise-threshold. Neurocomputing 2017, 219, 333–349 

I recommend adding (including) into the paper a Paragraph, dealing with this issue among others on the above references.

C. Also the reference to general FSOC mechanisms should be added, for example, among references:

- Le-Tran, M.; Kim, S. Performance Analysis of Dual-Hop Mixed Power Line Communication/Free-Space Optical Cooperative Systems. Photonics 2021, 8, 230

- Gaji´c, A.; Radovanovi´c, J.; Vukovi´c, N.; Milanovi´c, V.; Boiko, D.L. Theoretical approach to quantum cascade micro-laser broadband multimode emission in strong magnetic fields. Phys. Lett. A 2021, 387, 127007

- Pang, X.; Ozolins, O.; Zhang, L.; Schatz, R.; Udalcovs, A.; Yu, X.; Jacobsen, G.; Popov, S.; Chen, J.; Lourdudoss, S, Free-Space Communications Enabled by Quantum Cascade Lasers. Phys. Status Solidi A 2021, 218: 2000407

- Spitz, O.; Herdt, A.; Wu, J. et al. Private communication with quantum cascade laser photonic chaos. Nat. Commun. 2021, 12, 3327 (2021)

- Garlinska, M.; Pregowska, A.; Masztalerz, K.; Osial, M. From Mirrors to Free-Space Optical Communication—Historical Aspects in Data Transmission. Future Internet 2020, 12, 179

D. The quantitative comparison with other existing literature algorithms (papers) should be added in Section: Discussion, especially in taking into account accuracy. 

E. The language should be carefully revised. 

The idea presented and developed in the paper seems to be interesting and the results obtained are promising, but due to the above concerns, I would not recommend this paper for publication until the above comments/questions will be carefully addressed. At this moment I would recommend at least a Major Revision.

 

Author Response

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Reviewer 2 Report

In this paper authors provide a method to construct polar codes for FSO systems and analyze their performance in the presence of gamma-gamma turbulence.

I have the following concerns.

a) Why polar codes are more suitable than already establised LDPC, turbo codes, etc for FSO systems? Why is the problem interesting within the scope of FSO communications? Please elaborate.

b) Please discuss some practical issues on the implementation of such codes, e.g. in hardware. Is their implementation complexity lower than the one of existing codes?

c) Some details on the simulation of the system would be beneficial.

d) Some results on the performance of the coded system vs link distance might be interesting.

e) The writing can be improved in several parts of the text.

Author Response

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Reviewer 3 Report

I recommend that the manuscript should be rejected since it seems that there is room for improvement in this manuscript. I hope the comments listed below help the authors improve the manuscript.

(1) The grammar in the manuscript is problematic, which deteriorates the readability of the manuscript. For example, almost all sentences are written in the past form, even if they should be in the present form. Besides, the readers easily find a lot of typos. I require the author further improve their English and proofreading.

(2) What does the sentence "the reliability #10 > #01" mean? The symbol "#" is used without definition.

(3) The authors show some simulation results. However, they don't show how they perform the simulation. It was appreciated if the authors would add the details of the simulations.

(4) In Eq. (7), PW_7 should be PW_15.

(5) The authors should show the transmission rate of OOK and the time constant of the fading effect. This is because how the fading effect deteriorates the free-space optical communications is determined by these parameters.

 

Author Response

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Round 2

Reviewer 1 Report

The authors considered all my comments, and I recommend this paper for publication.

Reviewer 2 Report

I have no further comments

Reviewer 3 Report

I appreciate the authors' effort to improve the manuscript approaching all my comments, and I recommend this paper for publication.