Information Capacity of Turbulent and Absorptive Underwater Wireless Link with Perfect Laguerre–Gaussian Beam and Pointing Errors
Round 1
Reviewer 1 Report
1. Did authors consider execution of analysis of other parameters apart from the signal wavelength, the propagation distance, the seawater absorption and causing decreasing of average capacity of the wireless link in turbulent seawater?If so, please write which ones.
2. Did authors execute numerical analysis in no turbulent seawater?
If so, please write are there big differences in obtained results between analysis executed in no turbulent seawater and analysis executed in turbulent seawater?
3. Can a numerical analysis be executed for average capacity of the link with perfect Laguerre-Gaussian beam carrier and pointing errors in other mode than OAM mode? If so, please write which ones.
4. In the work there is no comparison of obtained results with other methods used for testing of average capacity of turbulent and absorptive underwater wireless link. Please insert comparative results obtained for other methods.
5. In the work in inserted conclusions there is no justification advantages method with using of the perfect Laguerre-Gaussian beam carrier in comparison to other methods.
Author Response
- Did authors consider execution of analysis of other parameters apart from the signal wavelength, the propagation distance, the seawater absorption and causing decreasing of average capacity of the wireless link in turbulent seawater? If so, please write which ones.
Response: That's a good question. Apart from signal wavelength, propagation distance, seawater absorption and causing decrease of the average capacity of the wireless link in turbulent seawater, scattering factors is one of the important factors causing decrease of the information. However, the relation between scattering and absorption of sea water and wavelength is different, and the analysis is more complicated if the two factors are considered simultaneously. Of course, considering the influence of seawater absorption and scattering on link channel capacity is what we are considering. To this end, in the conclusion section of the revised draft, we add to the limitations of this study that the loss of link channel capacity due to sea-water scattering is not taken into account.
- Did authors execute numerical analysis in no turbulent seawater? If so, please write are there big differences in obtained results between analysis executed in no turbulent seawater and analysis executed in turbulent seawater?
Response: Thank you very much for your advice. In Fig. 7 of the revised manuscript that shows the change relationship of system capacity under different dissipation rate of the mean-squared temperature and dissipation rate of kinetic energy per unit mass of fluid, we supplement the calculated results of the link channel capacity under the condition of the weakest turbulenceand (approximately no turbulence) .
- Can a numerical analysis be executed for average capacity of the link with perfect Laguerre-Gaussian beam carrier and pointing errors in other mode than OAM mode? If so, please write which ones.
Response: Thank you very much for your advice. According to the mathematical model of PLG, vortex free modes are all modes with m0=0. In the revised version, we have added the condition that m0 is not equal to 0.
- In the work there is no comparison of obtained results with other methods used for testing of average capacity of turbulent and absorptive underwater wireless link. Please insert comparative results obtained for other methods.
Response: Thank you very much for your advice. In the revised version, In figure 1 and Figure 2 of the revised manuscript, we add the numerical curve of the evolution of link channel capacity with POV carrier under the same conditions. It is concluded that PLG carrier link is superior to POV carrier link.
- In the work in inserted conclusions there is no justification advantages method with using of the perfect Laguerre-Gaussian beam carrier in comparison to other methods.
Response: Thank you very much for your advice. In the revised manuscript, we compared the transmission performance of PLG beam and POV beam, and found that the increase of transmission distance and turbulence intensity of PLG beam had less impact, and the information capacity of the system is higher.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The underwater wireless optical communication link with PLG beam is modeled. The mathematical analysis and simulation with transmission of the optical transmission system were done.There are no big English grammar issues. Figure quality looks fine. The literature search around 30 articles looks good. Thus, the manuscript could be minor revision if authors follow the guidelines.
1. Authors need to summarize all the simulated data in one separate Table.
2. Authors need to provide the Table which shows comparsion data of authors' work and previous other researchers' work before conclusion section.
3. In conclusion sections, authors had better emphasize the novelty and summarized data.
4. Authors need to show whole system block diagram for communication channels for UWOC link for the scholars who does not be familiar with the concept.
5. Limitation of the proposed research is not mentioned in the conclusion section.
6. Please do not use Fig. instead of Figure.
7. Please use italic letter if authors used that before.
8. Are there any simulated data for BER ?
9. In abstract section, authors must provide some important simulated data.
10. In Figure 1, capacity has no unit. How to determine that capacity?
Author Response
- Authors need to summarize all the simulated data in one separate Table.
Response: Thank you very much for your advice. According to your comment, we have listed the important parameters in Table 1 in the revised manuscript.
- Authors need to provide the Table which shows comparsion data of authors' work and previous other researchers' work before conclusion section.
Response: Thank you very much for your advice. According to your comment, we have provided the Table 2 which shows comparative data of authors' work and previous other researchers' work. And We added a comparison to the existing work of other researchers.
- In conclusion sections, authors had better emphasize the novelty and summarized data.
Response: Thank you very much for your advice. We revised the first three sentences of the conclusion of the manuscript to“This paper focuses on the influence of the anisotropy of ocean turbulence and the pointing error of the system on the information capacity of an optical communication link with PLG vortex beam as the carrier in the channel of a turbulence absorbing seawater does not take into account the scattering of seawater under 256-QAM modulation. The information capacity of optics communication link is derived based on the Rytov approximation. By comparing the loss of channel capacity of PLG and POV carrier links under the same conditions, which carrier is more suitable to be used as the optical communication carrier in the absorbing turbulent sea channel is studied, we have come to the important conclusion that the link composed of PLG carrier is better than that composed of POV carrier under the same conditions.”
- Authors need to show whole system block diagram for communication channels for UWOC link for the scholars who does not be familiar with the concept.
Response: Thank you very much for your advice. We have added the system model description diagram (see Figure 1) to the revised manuscript.
- Limitation of the proposed research is not mentioned in the conclusion section.
Response: Thank you very much for your advice. In the conclusion of the revised manuscript, we emphasize that the present results apply only to weak turbulence and do not take into account the effect of sea water scattering.
- Please do not use Fig. instead of Figure.
Response: Thank you very much for your advice. We have modified the Fig. to be Figure in the revised manuscript.
- Please use italic letter if authors used that before.
Response: Thank you very much for your advice. We have modified the parts of the paper that used italics at the beginning but not at the end.
- Are there any simulated data for BER ?
Response: That's a good question. In this paper, we study the channel capacity variation caused by the absorption of turbulent seawater and the optical system, so we use the theoretical model of channel capacity to analyze directly, without calculating the BER of the link separately.
- In abstract section, authors must provide some important simulated data.
Response: Thank you very much for your advice. We have added important simulation data to the abstract of the revised manuscript. The following describes the data to be added that is “The link with the carrier signal , , corresponds to the highest information capacity.”.
- In Figure 1, capacity has no unit. How to determine that capacity?
Response: Thank you very much for your advice. According to your comment, we have added units of capacity to the figure in the revised manuscript.
Author Response File: Author Response.pdf
