Design and Evaluation of Dynamic Topology for Mega Constellation Networks

Round 1

Reviewer 1 Report

Reviewer #

In the mega constellation network, recent studies proved its limitations in static topology to support the various communication between devices and impose cost overhead. The study aimed to overcome the challenge by employing two different versions of communication protocols of the Datagram Transport Layer Security 1-2 (DTLS1 and DTLS 2). The authors proposed a dynamic link allocation method based on total delay and hop counts between sender and receiver through the Dijkstra algorithm.

The research can appear successful in employing Mega constellation network benefits via solving the challenge of the static algorithm. Meanwhile, I have some concerns about the manuscript to publication, which are included:

In abstract

(1) The authors have to follow the standard format of problem definition, challenge clarification, and idea presentation in setting concepts of the abstract.

(2) Please, describe all abbreviations before employing them such as "DTLS 1" and "DTLS 2".

(3) I faced many typo and grammatical problems such as "the Dijkstra algorithm is used to obtain the random The average call distance of transmitted packets, the number of hops of packets forwarded and the total time delay are obtained in 66 time slices.".

(4) The outcomes of the research reflect a hesitation in the efficiency of improving the performance of the networks. Please, point out the role of partial improvements of delay, hop count, and distance in increasing the networks' efficiency.

(5) The presented sentences followed a complicated and obscure structure to the interpretation of the study's purposes. Please, utilize "The study" or "This work", etc to point out the idea for the first time.

In introduction

(6) Please, separate the point number and word in "1 Introduction" by marks such as ".", ")", etc.

(7) Please, describe all abbreviations before employing them such as "LEO" (low Earth orbit (LEO) of the van allen radiation belt), etc.

(8) I faced some typo and grammatical problems such as "to enhance collaboration between different networks[2].", "The simulation performance of the designed walker constellation network topology is mainly evaluated and compared in three aspects and the contributions are as follows.", etc.

(9) The sentences with complicated structures confuse the researchers about their concepts such as "For mega constellations, the large number of satellites and their high speed operation, as well as the constant changes with time, make the satellite topology very complex and require urgent analysis, optimization and evaluation.", etc.

(10) Please, reorganize the structure of the introduction section based on the standard form of problem definition, challenge recognition, and idea presentation to solve them. The authors presented a short explanation of the satellite problems in the recent era and pointed out the steps of the study. Meanwhile, their analysis is invisible to overcome the challenges.

(11) The authors referred to only two references for explaining the problem definition in the research era, which seems inappropriate to justify the challenges of satellite networks in the LEO range.

(12) Please, introduce the remaining sections of the manuscript in the last paragraph.

In related works

(13) Please, present an introduction of the section before starting subsections.

(14) I faced some grammatical problems such as "The typical dynamic link assignment policies that have been available can be summarized as the following two, which are generated based on the shortest distance policy and the longest visible time policy, respectively[5].", etc.

(15) Please, re-check and revise the reference number to adapt the resource. I faced some contradictions such as "NOAKES" and "[6]", etc. NOAKES et al. are related to [9] reference.

(16) Please, utilize a standard format (such as "Alhussein et al. [8] adapted")to refer to the references.

(17) The number of references is not enough for a research paper for publishing in a journal.

(18) The related work section has to review different studies to analyze their weaknesses and strong points in a research area. The authors presented the section as a background of the research study.

In problem analysis

(19) Please, separate the point number and word in "3 Problem analysis" by marks such as ".", ")", etc.

(20) Please, present an introduction of the section before starting its subsections.

(21) I faced some typo problems and complicated sentences such as "Based on the interstellar distance variation, a time slice division method based on the number of satellites per orbit can be constructed, which corresponds to the following Figure 1 , where S(2, x) represents the x satellite on 2 P and the core idea is summarized as follows.", etc.

(22) Please, define all parameters in Figure 1 such as "n", "x", etc.

(23) Due to the presented concepts, n described the total number of satellites, and x depicted the satellite index. I think that (x-(n-1)) is not correct if the authors followed the mentioned definitions of "n" and "x".

(24) Please, clarify that the matrix of the relationship between the vertices of the Graph consists of 65 elements (65*65).

(25) Please, describe all abbreviations before employing them such as " ISL", etc.

(26) Please, determine the related explanation to Figures 2 (a)-(b).

(27) Figure 2 (a) and Figure 2 (b) seem to be similar. Please, highlight their distinguish.

(28) Please, describe all existing parameters and variables in Table 2 such as "R", "T", etc.

(29) In the study, the authors updated the initial information of the network by any variations of its characteristics and set up a routing table to decide on link assignment. It seems to increase the memory capacity for storing network information. Please, justify the issue.

In modeling system approach

(30) Please, separate the point number and word in "4 Modeling system approach" by marks such as ".", ")", etc.

(31) Please, present an introduction of the section before starting its subsections.

(32) I faces some grammatical problems and complicated sentences such as "When a new service request is sent, there is no free channel in the whole satellite communication network, and there is bound to be a window where the service can be provided without the service system having to wait.", etc.

(33) The start and end points of the flowchart are invisible though some links are presented without pointers. Also, I faced an instruction and condition that pointed out "access to new call", which seems incorrect for a flowchart structure. Please, revise Figure 4.

(34) Why the authors aimed at the Manhattan mesh topology (as a partial mesh network) to specify the distance benchmark? Please, present its reason.

In performance evaluation

(35) Please, separate the point number and word in "5 Performance evaluation" by marks such as ".", ")", etc.

(36) Please, present an introduction of the section before starting its subsections.

(37) Please, describe all abbreviations before employing them such as "STLS", "MHD", etc.

(38) Please, report the delay based on its average value in Figure 8. I found overtaking its value for DTLS 1 compared to DTLS 2 where the authors claimed improving delay and performance for DTLS 1. Since I think proves the issue by reporting average value.

(39) I faced some typo and grammatical problems such as "Since the smaller the average call distance of data transmission packets, the better the network performance, DTLS1 performs better.", etc.

In finally,

Please, justify the idea of comparing Q-learning in adopting routing algorithms of the mega constellation networks.

Please, revise the manuscript in technical writing with high accuracy.  

 

 

 

 

 

 

Comments for author File: Comments.pdf

Author Response

Reviewer #1:

[General] As requested by the reviewers, we have reorganized the text parts of the abstract and introduction to highlight the key points, innovations, and shortcomings of previous work. And an introductory paragraph was added at the beginning of each subsection to make the text more readable. Some grammatical errors have been corrected, and the language of the whole article has been touched up. The modified parts of the diagrams are explained accordingly to make the method section more rigorous. Some references have been added to make the article more justifiable. Finally, the reviewers' questions were answered one by one, and all the revised parts were marked in red font.

 

In abstract

1. Response to comment: The authors have to follow the standard format of problem definition, challenge clarification, and idea presentation in setting concepts of the abstract.

Response: We have reworked the logic of the abstract based on the reviewers' suggestions. The problem is first presented to clarify the limitations of the static network topology of the constellation. Then, the topologies of several types of designs are defined, the simulation work of this study is summarized and the corresponding conclusions are obtained. The abstract is more clearly organized and focused after the revision.

 

2. Response to comment: Please, describe all abbreviations before employing them such as "DTLS 1" and "DTLS 2".

Response: Considering the Reviewer’s suggestion, we have added descriptions before all team abbreviations. For example, in line 11, ISLs is an abbreviation for inter-satellite links; the same is done for STLS in line 13 and DTLS in line 14.

 

3. Response to comment: I faced many typo and grammatical problems such as "the Dijkstra algorithm is used to obtain the random The average call distance of transmitted packets, the number of hops of packets forwarded and the total time delay is obtained in 66-time slices."

Response: We’re sorry that this is a writing error caused by a lack of careful checking. The sentences mentioned in the comment have been modified accordingly to correspond to this part of the summary " the Dijkstra algorithm is used to obtain the random paths between any 10,000 pairs of urban ground stations, and the time slice division strategy is adopted. Finally, three indexes, namely the average call distance of transmitted packets, the number of hops of packet forwarding and the total delay are obtained within 66 time slices.", Lines 16~18 in red.

 

4. Response to comment: The outcomes of the research reflect a hesitation in the efficiency of improving the performance of the networks. Please, point out the role of partial improvements of delay, hop count, and distance in increasing the networks' efficiency.

Response: In lines 20 to 22, based on the simulation results, it is added that the DTLS1 integrated network has the best performance and can transmit traffic quickly in any direction through the reverse track, which verifies the relevant assumptions in applications.

 

5. Response to comment: The presented sentences followed a complicated and obscure structure to the interpretation of the study's purposes. Please, utilize "The study" or "This work", etc to point out the idea for the first time.

Response: Some of the sentence structures in the abstract do seem a bit complex and vague. A more rigorous statement is used to illustrate the point, replacing the subject with "this study" in line 13.

 

In introduction

6. Response to comment: Please, separate the point number and word in "1 Introduction" by marks such as ".", ")", etc.

Response: The word in "1 Introduction" is already separated by marks ".".

 

7. Response to comment: Please, describe all abbreviations before employing them such as "LEO" (low Earth orbit (LEO) of the van allen radiation belt), etc .

Response: The words designed to be abbreviated in the article have been described where they first appear, and a summary of the abbreviations is given at the end of the article.

 

8. Response to comment: I faced some typo and grammatical problems such as "to enhance collaboration between different networks[2].", "The simulation performance of the designed walker constellation network topology is mainly evaluated and compared in three aspects and the contributions are as follows.", etc.

Response: The typos and grammatical parts listed by the reviewer have been corrected in the new version of the article, please check lines 38~39 in the text.

 

9. Response to comment: The sentences with complicated structures confuse the researchers about their concepts such as "For mega constellations, a large number of satellites and their high-speed operation, as well as the constant changes with time, make the satellite topology very complex and require urgent analysis, optimization and evaluation.", etc.

Response: The sentences listed by the reviewer as structurally complex have been revised in the new version of the article， please check lines 49 to 51 in the text.

 

10. Response to comment: Please, reorganize the structure of the introduction section based on the standard form of problem definition, challenge recognition, and idea presentation to solve them. The authors presented a short explanation of the satellite problems in the recent era and pointed out the steps of the study. Meanwhile, their analysis is invisible to overcome the challenges.

Response: We have reworked the introduction based on the reviewers' suggestions. Firstly, we present the background of the integrated air, space, and ground network and the characteristics of mega-constellations. Next, we define the constellation network topology and point out the challenges in the development of related work. Finally, we summarize the simulation work of this study and illustrate the contributions of the article. The revised introduction is more clearly organized and focused.

 

11. Response to comment: The authors referred to only two references for explaining the problem definition in the research era, which seems inappropriate to justify the challenges of satellite networks in the LEO range.

Response: The introduction has been revised, and some additional text has been added to explain the challenging and contemporary context, as well as three references, making it more informative and easier to read and understand.

 

12. Response to comment: Please, introduce the remaining sections of the manuscript in the last paragraph.

Response: As you suggested, we have introduced the remaining sections of the manuscript in the last paragraph. For details, please refer to lines 77~82 in the text.

 

In related works

13. Response to comment: Please, present an introduction of the section before starting subsections.

Response: As suggested by the reviewers, we have presented an introduction to the section before starting subsections.

 

14. Response to comment: I faced some grammatical problems such as "The typical dynamic link assignment policies that have been available can be summarized as the following two, which are generated based on the shortest distance policy and the longest visible time policy, respectively[5].",etc.

Response: The typos and grammatical parts listed by the reviewer have been corrected in the new version of the article, please check lines 100~102 in the text.

 

15. Response to comment: Please, re-check and revise the reference number to adapt the resource. I faced some contradictions such as "NOAKES" and "[6]", etc. NOAKES et al. are related to [9] reference.

Response: We have revised the reference number to adapt the resource, etc. NOAKES et al. are related to [9] reference, please check line 117.

 

16. Response to comment: Please, utilize a standard format (such as "Alhussein et al. [8] adapted")to refer to the references.

Response: All references in the article have been in a standard format, such as "Alhussein et al. [8] adapted" in line 126.

 

17. Response to comment: The number of references is not enough for a research paper for publishing in a journal.

Response: The revised version of the article has made up for the quantitative shortfall in the number of references, added relevant citations to the new content, and added sentences that lacked citations in the original text. Two works of literature related to dynamic network topologies are added and the shortcomings of these works are analyzed.

 

18. Response to comment: The related work section has to review different studies to analyze their weaknesses and strong points in a research area. The authors presented the section as a background of the research study.

Response: The section on related work provides an overview of various studies, highlighting their respective focuses. Subsequently, the limitations of these studies are analyzed and summarized. This analysis is followed by a discussion of the implications that arise from these shortcomings, as well as a demonstration of the strengths and innovations of this present article. For a comprehensive summary of the deficiencies in previous works, please refer to lines 139-143 in the revised version of this paper.

 

In problem analysis

19. Response to comment: Please, separate the point number and word in "3 Problem analysis" by marks such as ".", ")", etc.

Response: The word in "3 Problem analysis " is already separated by marks ".".

 

20. Response to comment: Please, present an introduction of the section before starting its subsections.

Response: As suggested by the reviewers, we have presented an introduction to the section before starting the subsections. Please refer to lines 152~157.

 

21. Response to comment: I faced some typo problems and complicated sentences such as "Based on the interstellar distance variation, a time slice division method based on the number of satellites per orbit can be constructed, which corresponds to the following Figure 1, where S(2, x) represents the x satellite on 2 P and the core idea is summarized as follows.", etc.

Response: The typos and grammatical parts listed by the reviewer have been corrected in the new version of the article, please check lines 189~194in the text.

 

22. Response to comment: Please, define all parameters in Figure 1 such as "n", "x", etc.

Response: All parameters appearing in Figure 1 have been defined. "n" is the number of satellites per orbit, which is also the number of time slices divided, and "x" represents the satellite x in a given orbit. Please refer to lines 191~194 of the revised paper.

 

23. Response to comment: Due to the presented concepts, n described the total number of satellites, and x depicted the satellite index. I think that (x-(n-1)) is not correct if the authors followed the mentioned definitions of "n" and "x".

Response: All parameters appearing in Figure 1 have been defined. "n" is the number of satellites per orbit, which is also the number of time slices divided, and "x" represents the satellite x in a given orbit. Explained by such a definition, (x-(n-1)) makes sense.

 

24. Response to comment: Please, clarify that the matrix of the relationship between the vertices of the Graph consists of 65 elements (65*65).

Response: The satellite nodes next to each other are not relationship matrices, but are numbered for ease of description. As explained above, S(65, 65) represents the 65h satellite in the 65h orbit, so there is no contradiction.

 

25. Response to comment: Please, describe all abbreviations before employing them such as " ISL", etc.

Response: The words designed to be abbreviated in the article have been described where they first appear, and a summary of the abbreviations is given at the end of the article. For example, the abbreviation for inter-satellite link is ISL.

 

26. Response to comment: Please, determine the related explanation to Figures 2 (a)-(b).

Response: Please refer to line 233 of the revised article, where Figure 2-(a) is defined as two intra-OP ISLs plus one AOPL, and Figure 2-(b) is defined as one intra-OP ISL plus two AOPLs. The relevant abbreviations are explained in detail in lines 207~211.

 

27. Response to comment: Figure 2 (a) and Figure 2 (b) seem to be similar. Please, highlight their distinguish.

Response: The specific differences between the two methods are defined in lines 209 ~ 211.

 

28. Response to comment: Please, describe all existing parameters and variables in Table 2 such as "R", "T", etc.

Response: In Table 2, there are some parameters that did have missing descriptions before. In the revised version of the study, the parameters used are specified, and the documentation of the source of the calculations has been added to make the analysis process of the problem method more transparent and understandable. Please refer to lines 256~261 of the article.

 

29. Response to comment: In the study, the authors updated the initial information of the network by any variations of its characteristics and set up a routing table to decide on link assignment. It seems to increase the memory capacity for storing network information. Please, justify the issue.

Response: Firstly, the paper does not update the initial information based on arbitrary changes in network features; instead, it focuses on the relevant parameters of the time-slice division strategy mentioned earlier. Secondly, the dynamic link selection algorithm does not increase network storage, as the link information in the satellite routing is updated in real-time and only retains the corresponding data from the previous and current time slices without adding redundancy.

 

In modeling system approach

30. Response to comment: Please, separate the point number and word in "4 Modeling system approach" by marks such as ".", ")", etc.

Response: The word in "4 Modeling system approach" is already separated by marks ".".

 

31. Response to comment: Please, present an introduction of the section before starting its subsections.

Response: As suggested by the reviewers, we have presented an introduction to the section before starting the subsections. Please refer to lines 264~269.

 

32. Response to comment: I face some grammatical problems and complicated sentences such as "When a new service request is sent, there is no free channel in the whole satellite communication network, and there is bound to be a window where the service can be provided without the service system having to wait.", etc.

Response: The typos and grammatical parts listed by the reviewer have been corrected in the new version of the article, please check lines 272~274 in the text.

 

33. Response to comment: The start and end points of the flowchart are invisible though some links are presented without pointers. Also, I faced an instruction and condition that pointed out "access to new call", which seems incorrect for a flowchart structure. Please, revise Figure 4.

Response: The main flowchart in Figure 4 is the overall simulation framework, which is the flowchart on the right side, and the call access process on the left side is a complementary description of the call formation process. After the modification, the "new call" frame is no longer the end of the flowchart, but an intermediate process. The command "access to new call" has been removed to make the structure of the flowchart more accurate and clearer.

 

34. Response to comment: Why the authors aimed at the Manhattan mesh topology (as a partial mesh network) to specify the distance benchmark? Please, present its reason.

Response: Manhattan network(MHD) defines a mesh connection distinguished by high stability, low latency, and strong resistance to damage. Among the static topologies discussed in Section 2.1, the mesh topology is most commonly utilized in the static structure of LEO satellite constellations. For instance, the OneWeb constellation's fixed topology adopts a mesh configuration, rendering MHD a more representative choice. The corresponding explanation is given in lines 360 to 364 of the paper.

 

In performance evaluation

35. Response to comment: Please, separate the point number and word in "5 Performance evaluation" by marks such as ".", ")", etc.

Response: The word in "5 Performance evaluation" is already separated by marks ".".

 

36. Response to comment: Please, present an introduction of the section before starting its subsections.

Response: As suggested by the reviewers, we have presented an introduction to the section before starting the subsections. Please refer to lines 373~377.

 

37. Response to comment: Please, describe all abbreviations before employing them such as "STLS", "MHD", etc.

Response: The words designed to be abbreviated in the article have been described where they first appear, and a summary of the abbreviations is given at the end of the article.

 

38. Response to comment: Please, report the delay based on its average value in Figure 8. I found overtaking its value for DTLS1 compared to DTLS 2 where the authors claimed improving delay and performance for DTLS1. Since I think proves the issue by reporting average value.

Response: The total delay is a combination of propagation delay and processing delay. In Figure 8, the data analysis part is based on the average of the values of this topology. The postponement of DTLS1 fluctuates and is indeed larger than DTLS2 at some times. However, from the overall point of view, the average value of DTLS1 is still smaller than that of DTLS2, which is more explanatory.

 

39. Response to comment: I faced some typo and grammatical problems such as "Since the smaller, the average call distance of data transmission packets, the better the network performance, DTLS1 performs better.", etc.

Response: The typos and grammatical parts listed by the reviewer have been corrected in the new version of the article, please check lines 400~401 in the text.

 

Finally, the English of this paper has been revised. The language has been greatly improved from the previous version, and the incoherencies pointed out by the reviewers have been corrected. Thank you for the detailed review, I found the reviewer’s comments quite helpful, and I revised my paper point-by-point.

Author Response File: Author Response.pdf

Reviewer 2 Report

I consider the manuscript is novelty and it presents an interest about the mega constellation networks.
Some observations:
The paper is properly structured. The problem is clearly defined The proposal is developed consistently The conclusions I think could be strengthened

 

Author Response

Reviewer #2:

 Response to comment: The conclusions I think could be strengthened.

Response: The conclusion has been adjusted to make it more focused and organized than before.

 

Thank you very much for your comments and suggestions.

Reviewer 3 Report

Please see the attached file.

Comments for author File: Comments.pdf

Author Response

Reviewer #3:

1. Response to comment: The abbreviations in the paper seem to be less standardized and should be stated in parentheses after the words when they appear the first time.

Response: The words designed to be abbreviated in the article have been described where they first appear, and a summary of the abbreviations is given at the end of the article. For example, the abbreviation for an inter-satellite link is ISL.

 

2. Response to comment: The introduction part should be revised carefully to make the motivation and contribution clearer.

Response: We have reworked the introduction based on the reviewers' suggestions. Firstly, we present the background of the integrated air, space, and ground network and the characteristics of mega constellations. Next, we define the constellation network topology and point out the challenges in the development of related work. Finally, we summarize the simulation work of this study and illustrate the contributions of the article. The revised introduction is more clearly organized and focused.

 

3. Response to comment: References should be added for the statistical introduction. For example, “The global population data as of 2020 is about 7.970 billion, the per capita broadband demand is

about 10 Mbps, and the total transmission rate demand is about 796.96 Tbps.” Please include citations to support those statements.

Response: For that part of the sentence references to the literature have been added to the citation. Please check line 282.

 

4. Response to comment: It is suggested to introduce the following recent works in satellite network [R1] field to highlight the state-of-the-art of this paper.

[R1] “Supporting IoT with rate-splitting multiple access in satellite and aerial-integrated

networks,” IEEE Internet of Things Journal, vol. 8, no. 14, pp. 11123-11134, Jul. 2021.

Response: The reference is of good value to the article and has therefore been added to the citation.

 

5. Response to comment: There are some grammatical errors and detailing issues in this article that are worth noting, such as Line 261, “path P route”- This seems to be some semantic repetition.

Response: Delete the word “route”. The typos and grammatical parts listed by the reviewer have been corrected in the new version of the article, please check line 318 in the text.

 

6. Response to comment: In this paper, MHD network is chosen as a static benchmark topology, please explain the characteristics of this type of topology.

Response: Manhattan network(MHD) defines a mesh connection distinguished by high stability, low latency, and strong resistance to damage. Among the static topologies discussed in Section 2.1, the mesh topology is most commonly utilized in the static structure of LEO satellite constellations. For instance, the OneWeb constellation's fixed topology adopts a mesh configuration, rendering MHD a more representative choice. The corresponding explanation is given in lines 360 to 364 of the paper.

 

We tried our best to improve the manuscript and made some changes in the manuscript. Besides, we have carefully and thoroughly proofread the manuscript to correct all the grammar and typos.

 

We appreciate for Editors/Reviewers’ warm work earnestly and hope that the correction will meet with approval.

 

Once again, thank you very much for your comments and suggestions.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Reviewer # 1:

The authors were well-tried to solve the mentioned problems. Meanwhile, some of them remain as the following concerns:

18. Response to comment: The related work section has to review different studies to analyze their weaknesses and strong points in a research area. The authors presented the section as a background of the research study.

Response: The section on related work provides an overview of various studies, highlighting their respective focuses. Subsequently, the limitations of these studies are analyzed and summarized. This analysis is followed by a discussion of the implications that arise from these shortcomings, as well as a demonstration of the strengths and innovations of this present article. For a comprehensive summary of the deficiencies in previous works, please refer to lines 139-143 in the revised version of this paper.

Re-comment: Please, address the main references of the mentioned topologies in Table 1 (such as star topology [x]).

21. Response to comment: I faced some typo problems and complicated sentences such as "Based on the interstellar distance variation, a time slice division method based on the number of satellites per orbit can be constructed, which corresponds to the following Figure 1 , where S(2, x) represents the x satellite on 2 P and the core idea is summarized as follows.", etc.

Response: The typos and grammatical parts listed by the reviewer have been corrected in the new version of the article, please check lines 189~194in the text.

Re-comment: The typo problem remains a challenge, again. The authors have to employ ":" instead of "." when mentioning some concepts in continue by "as follow". Please, apply the addressed comment on all parts of the manuscript.

23. Response to comment: Due to the presented concepts, n described the total number of satellites, and x depicted the satellite index. I think that (x-(n-1)) is not correct if the authors followed the mentioned definitions of "n" and "x".

Response: All parameters appearing in Figure 1 have been defined. "n" is the number of satellites

per orbit, which is also the number of time slices divided, and "x" represents the satellite x in a given orbit. Explained by such a definition, (x-(n-1)) makes sense.

Re-comment: Please, clarify that the authors defined the time slice based on the number of satellites per orbit. The authors have to explain their approach, decisively. Some words reflect the speculation and uncertain concept of the method such as "can be constructed" and “can”.

New comment: Please, clarify the relationship between "n" and "x". The mentioned definition applies when the (x ≥n) condition is met.

24. Response to comment: Please, clarify that the matrix of the relationship between the vertices of the Graph consists of 65 elements (65*65).

Response: The satellite nodes next to each other are not relationship matrices, but are numbered for ease of description. As explained above, S(65, 65) represents the 65h satellite in the 65h orbit, so there is no contradiction.

Re-comment: All parameters can reflect a 2D matrix when demonstrated on the 2D vector. Anyway; Please, define the range of "y" and "z", and their distinction with "x" and "n".

26. Response to comment: Please, determine the related explanation to Figures 2 (a)-(b).

Response: Please refer to line 233 of the revised article, where Figure 2-(a) is defined as two intra-OP ISLs plus one AOPL, and Figure 2-(b) is defined as one intra-OP ISL plus two AOPLs. The relevant abbreviations are explained in detail in lines 207~211.

Re-comment: Please, attend that you have to address the related explanations to the Figures by pointing out their labels such as "as shown in Figures 2 (a)-(c)" or other structures and formats. The authors presented the related explanations of Figures 2 (a)-(c) without addressing their labels.

27. Response to comment: Figure 2 (a) and Figure 2 (b) seem to be similar. Please, highlight their distinguish.

Response: The specific differences between the two methods are defined in lines 209 ~ 211.

Re-comment: Please, attend to the mentioned comment. It pointed out the Figures, not their explanations. Figures 2 (a) and (b) are similar.

28. Response to comment: Please, describe all existing parameters and variables in Table 2 such as "R", "T", etc.

Response: In Table 2, there are some parameters that did have missing descriptions before. In the revised version of the study, the parameters used are specified, and the documentation of the source of the calculations has been added to make the analysis process of the problem method more transparent and understandable. Please refer to lines 256~261 of the article.

New comment: Please, revise the "Table 2" label to "Figure" or "Algorithm". The authors presented an algorithm, not a Table.

29. Response to comment: In the study, the authors updated the initial information of the network by any variations of its characteristics and set up a routing table to decide on link assignment. It seems to increase the memory capacity for storing network information. Please, justify the issue.

Response: Firstly, the paper does not update the initial information based on arbitrary changes in network features; instead, it focuses on the relevant parameters of the time-slice division strategy mentioned earlier. Secondly, the dynamic link selection algorithm does not increase network storage, as the link information in the satellite routing is updated in real-time and only retains the corresponding data from the previous and current time slices without adding redundancy.

 

Re-comment: The authors presented a similar concept to update the "initial information" by pointing out "real-time updating". Please, add a data storage capacity report. It is an essential parameter in the research area.

Comments for author File: Comments.pdf

Author Response

[general] In response to the reviewers' new comments, we have made point-by-point changes and explanations, and all the revised parts were marked in red font.

 

18. Re-comment: Please, address the main references of the mentioned topologies in Table 1 (such as star topology [x]).

Re-response: References [6] and [7] mention relevant background information on static topologies. In view of the reviewer's suggestion, we have added literature on star topologies [8],and on mesh topologies [9]. The remaining two types of topology are described in the references and therefore, the references are not explicitly cited.

 

21. Re-comment: The typo problem remains a challenge, again. The authors have to employ ":" instead of "." when mentioning some concepts in continue by "as follow". Please, apply the addressed comment on all parts of the manuscript.

Re-response: Some of the symbols have been changed following the reviewers' comments. Please check lines 194, 307, and 386 of the revised version of the paper.

 

 

23. Re-comment: Please, clarify that the authors defined the time slice based on the number of satellites per orbit. The authors have to explain their approach, decisively. Some words reflect the speculation and uncertain concept of the method such as "can be constructed" and “can”.

Re-response:

(1)The paper begins by presenting the principles of time slice delineation. It is pointed out in section 3.1 that the large number of satellites in the giant constellation makes the algorithm's complexity high and b not conducive to the development of the routing algorithm if the time slices are not divided. Therefore, this paper proposes a time slice partitioning method based on the number of satellites per orbit, making it more applicable for different constellations. In this paper, the walker constellation is assumed to have 24 orbits and 66 satellites per orbit, so 66-time slices are divided, i.e., n = 66. This facilitates the division of the giant constellation into regular t-topologies, which can be used for link prediction and routing analysis using their unique periodicity, significantly reducing the computational effort.

(2) Some words lack certainty in their tone, which is primarily a linguistic issue that we may have overlooked in our work as English is not our mother tongue. As suggested by the reviewer, the words “can be constructed” and “can be” have been amended. Please check lines 100, 179, 189, 272, 332, and 347 in the text.

New comment: Please, clarify the relationship between "n" and "x". The mentioned definition applies when the (x ≥n) condition is met.

Re-response: In lines 191-195 of the document, definitions are first established for S(i,j) and Tn based on the theory of satellite numbering within constellations, and the ranges of i, j, and n are specified. Then, using S(2,x) as an example, the core idea of the method is summarized. In lines 197-199, the meanings of x, n, y, and z are explained, and their ranges are specified. While both x and n range from 1 to 66, they are not directly related. When n changes, it represents the selection of time slots, indicating temporal changes. When x changes, it means the choice of individual satellites within a time slice, demonstrating differences in the constellation's operation.

 

24. Re-comment: All parameters can reflect a 2D matrix when demonstrated on the 2D vector. Anyway; Please, define the range of "y" and "z", and their distinction with "x" and "n".

Re-response: As stated earlier, explanations for the variables used and their relationships were provided in lines 191-200 of the revised paper. Please refer to it for further details.

 

 

26. Re-comment: Please, attend that you have to address the related explanations to the Figures by pointing out their labels such as "as shown in Figures 2 (a)-(c)" or other structures and formats. The authors presented the related explanations of Figures 2 (a)-(c) without addressing their labels.

Re-response: In lines 239-240 of the paper, explanations for the labels were added at the bottom of Figure 2, addressing the label issue raised by the reviewer.

 

 

27.Re-comment: Please, attend to the mentioned comment. It pointed out the Figures, not their explanations. Figures 2 (a) and (b) are similar.

Re-response: The reason for the identical numbers is that the same satellites are involved in both figures. Figure 2 primarily focuses on the combination methods of three fixed links, which are explained below the figure. The three fixed links constitute the fundamental structure for dynamic topology design. We fully understand the reviewer's concerns about the similarity between the two figures and hope that this explanation will adequately address your questions.

 

 

28. New comment: Please, revise the "Table 2" label to "Figure" or "Algorithm". The authors presented an algorithm, not a Table.

Re-response: The "Table 2" has been changed to "Algorithm 1" in the text, and the numbering of subsequent tables has been modified to ensure accuracy. Please refer to line 267 for more information.

 

29. Re-comment: The authors presented a similar concept to update the "initial information" by pointing out "real-time updating". Please, add a data storage capacity report. It is an essential parameter in the research area.

Re-response: The software used in the network simulation section of this article is NS2, which saves the entire simulation process through Trace files. The routing protocol includes protocol entities, routing tables, timers, log recorders, and routing cache queues. The Route Cache Timer calls the “rt_purge()” function to clear expired routes in the routing table and discard related packets when it times out, then calls schedule() to set the next time it will be called. This explains the relevant questions about network storage memory, where nodes only store the required routes, reducing memory requirements.

Regarding the "data storage capacity report" mentioned by the reviewer, the bandwidth between satellites in this simulation is set to 30MB, while the bandwidth between satellites and ground stations is set to a smaller value of 4MB. The theoretical upper limit of storage capacity is related to the memory of the hard disk, and this simulation has not generated any storage capacity errors. The specific upper limit estimate requires testing the software boundary. The content of the routing table in the method mainly involves network addresses, subnet masks, and next-hop addresses, and uses a classifier as the entry point for nodes. Its function is to use the routing table to forward received packets according to certain rules. The relevant parameters are related to the research project of the research group, so the "data storage capacity report" may not be publicly disclosed, and I hope you can understand.

 

 

We tried our best to improve the manuscript and made some changes in the manuscript. Besides, we have carefully and thoroughly proofread the manuscript to correct all the grammar and typos.

 

We appreciate for Editors/Reviewers’ warm work earnestly and hope that the correction will meet with approval.

Author Response File: Author Response.pdf

Round 3

Reviewer 1 Report

The authors did not appear successful to overcome the mentioned concerns. They persisted to justify the problems instead of solving them such as a simple case:

Addressing Figure 2 on the text (no adding the additional explanations)

Author Response

Dear Editors and Reviewers:

Thank you very much for your valuable comments, which have helped a lot to improve our paper. Based on the reviewers' suggestions, we have again revised the article. Please refer to the attached document.

Author Response File: Author Response.pdf