Flying Base Station Channel Capacity Limits: Dependent on Stationary Base Station and Independent of Positioning^†

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

• In Section 4.1.2 (Proof of Theorem 1), consider providing a more detailed explanation or visual representation of Jensen's Inequality application to aid reader comprehension.
• In Section 5.2 (Capacity Gain in Full-Duplex Case), highlight the specific algebraic steps and derivations for the proof of Theorem 4, as they are omitted in the current version.
• Section 6.3 (Beneficial Region and Transmission Power Requirement) could benefit from additional visual aids (e.g., graphs or diagrams) to better illustrate the beneficial region thresholds and their dependencies on various parameters. Cross-ref this https://doi.org/10.1016/j.adhoc.2024.103463
• Consider expanding the discussion on the practical implications and potential challenges of implementing flying base stations, particularly concerning mobility constraints, energy efficiency, and hardware limitations. Cross-ref this https://doi.org/10.1016/j.geits.2023.100130

Author Response

We thank the anonymous reviewers for their invaluable feedback and comments. We revised and improved our manuscripts thanks to them. In the manuscript, we highlight the additions and changes in blue-color font. The following provides a point-to-point response to describe how each comment (italicized in this note) informed our revisions.

 

• In Section 4.1.2 (Proof of Theorem 1), consider providing a more detailed explanation or visual representation of Jensen's Inequality application to aid reader comprehension.

We added more detailed explanation in the Theorem 1 proof.

 

• In Section 5.2 (Capacity Gain in Full-Duplex Case), highlight the specific algebraic steps and derivations for the proof of Theorem 4, as they are omitted in the current version.

We added Appendix A and revise Section 5.2 to provide the full proof including the algebraic steps and derivations.

 

• Section 6.3 (Beneficial Region and Transmission Power Requirement) could benefit from additional visual aids (e.g., graphs or diagrams) to better illustrate the beneficial region thresholds and their dependencies on various parameters. Cross-ref this https://doi.org/10.1016/j.adhoc.2024.103463

We added Figure 5(b) and made the relevant revisions in Section 6.3. Figure 5(b) focuses on one case of the previously existing Figure 5(a) but provides different visualization to show the beneficial region by coloring it.

This paper citation has been added in Sections 2 and 7.2. It is [17] in the updated manuscript.

 

• Consider expanding the discussion on the practical implications and potential challenges of implementing flying base stations, particularly concerning mobility constraints, energy efficiency, and hardware limitations. Cross-ref this https://doi.org/10.1016/j.geits.2023.100130

We revised Section 7.2 and included the citation of this paper, [34] in the updated manuscript. We also explicitly stated that Section 7 is largely driven by the challenges and limitations in the Section 7 header, as our future directions are motivated by them.

Reviewer 2 Report

Comments and Suggestions for Authors

 

Paper title: Flying Base Station Channel Capacity Limit: Dependent on Stationary Base Station and Independent of Positioning

 

 

 

My decision is major revision.

 

 

This paper focused on the flying base station channel capacity to build on the Shannon channel capacity, which quantifes the upper-bound limit of the rate at which information can be reliably transmitted using the communication channel regardless of the modulation and coding techniques used. I have some questions:

 

-        In Introduction part, authors did not compare with another paper much. Authors should include more references.

-        The contributions did not mentioned clearly in Introduction part.

-        In manuscript, authors mentioned about mobility effect, however, it did not shows in results. Authors may show implementation/simulation results, figure, table, or equations related about the effect of mobility for Flying Base Station Channel Capacity (not only path loss exponent). With flying channel, results are not enough because you did not include mobility effect in the simulation results in figure 2, 3, 4, and 5.

-        Figure 1 (shows the scenario of architecture) should be explain more. What shows between BS and Core network? In manuscript, authors just mention about  user (U), flying base station (F), and stationary terrestrial base station (S). If not necessary, you may delete Core network.

-        Title of section 7 should be changed. Such as: Discussion and Future works.

-        Conclusion part shoud write more about results and future works.

 

Finally, I hope you will solve all the issues that I mentioned above to make your paper better.

 

 

Comments on the Quality of English Language

No comment.

Author Response

We thank the anonymous reviewers for their invaluable feedback and comments. We revised and improved our manuscripts thanks to them. In the manuscript attached, we highlight the additions and changes in blue-color font. The following provides a point-to-point response to describe how each comment (italicized in this note) informed our revisions.

 

This paper focused on the flying base station channel capacity to build on the Shannon channel capacity, which quantifes the upper-bound limit of the rate at which information can be reliably transmitted using the communication channel regardless of the modulation and coding techniques used. I have some questions:

-        In Introduction part, authors did not compare with another paper much. Authors should include more references.

We added more survey/review paper references [6,7] in the Introduction section to better establish the importance of flying base station; these references will supplement the existing ones to further support that flying base station is an active research field and its use will expand in future networking.

For the research papers which are more precisely related to our research contribution, we revise the sentence to explicitly state that we discuss them in the following Related Work section, Section 2. The Introduction section provides an overview of our research vs. previous research; however, we provide more details in describing the previous work and comparing them with our work in Section 2.

 

-        The contributions did not mentioned clearly in Introduction part.

We introduced subsubsections to better highlight our contributions and divide the paragraph describing them. The subsection titled “Our Contributions” is followed by another titled “Paper Organization” to avoid having just one subsubsection.

 

-        In manuscript, authors mentioned about mobility effect, however, it did not shows in results. Authors may show implementation/simulation results, figure, table, or equations related about the effect of mobility for Flying Base Station Channel Capacity (not only path loss exponent). With flying channel, results are not enough because you did not include mobility effect in the simulation results in figure 2, 3, 4, and 5.

We assume a connectivity-provision-dedicated flying base station which uses its mobility to position itself for the optimal/maximum channel capacity. The ideal transmission-optimal location, enabled by the mobility, achieves the flying base station channel capacity, as we define and introduce in this research paper. The flying base station channel capacity addresses the following question: Given the user and the stationary base station, what is the channel capacity a flying base station can provide using its mobility and transmission-optimal positioning? We revised Section 3.2 to better explain that the mobility materializes in the distances. We also revised Section 4 header to reiterate the flying base station’s objective, to motivate our analysis of the transmission-optimal location, and to provide the base for focusing on the transmission-optimal location for the flying base station channel capacity.

 

-        Figure 1 (shows the scenario of architecture) should be explain more. What shows between BS and Core network? In manuscript, authors just mention about  user (U), flying base station (F), and stationary terrestrial base station (S). If not necessary, you may delete Core network.

Figure 1 is described in Section 3.1 to provide the relevant entities in mobile networking. Figure 1 also depicts why flying base station inherently cannot be a standalone and relies on the stationary base station serving as the bridge gateway between wireless vs. wired, e.g., the base stations alone cannot provide the remote access and connectivity. The reliance is important because our research focuses on the reliance/dependency of the flying base station on the stationary base station. We added a clarification sentence in the Figure 1 caption to better describe this.

 

-        Title of section 7 should be changed. Such as: Discussion and Future works.

We changed the title of Section 7 to “Discussions and Future Directions.”

 

-        Conclusion part shoud write more about results and future works.

We revised the Conclusion section to highlight the key takeaways of our analyses results and explicitly stated that we include the discussions for future directions.

 

Finally, I hope you will solve all the issues that I mentioned above to make your paper better.

Thank you for your comments and feedback.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The substantial revisions you have made have significantly improved the quality of the manuscript.

Thank you for your diligent efforts in improving the manuscript and incorporating the original feedback provided.

 

Reviewer 2 Report

Comments and Suggestions for Authors

All comments were revised clearly.