A Throughput Performance Analysis Method for Multimode Underwater Acoustic Communication Network Based on Markov Decision Process

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper considered the different communication capabilities of different links and proposed a decoding conflict model to support concurrent transmission scenarios. Simulations were also performed to evaluate the effectiveness of the proposed scheme. However, some concerns should be carefully addressed before its publication.

 

1. In the abstract, the authors should address the novelty and improvement of the proposed scheme and shorten the statements for the research background. And the numerical results are suggested to be provided in the abstract to verify the effectiveness of the proposed scheme.

2. The language of the article needs improvement, as in Line 23, 32, 449.

3. In the introduction, more related work are suggested to be provided for comparison so as to address the novelty of the paper.

4. The format for S_j,t should be unified. And the details of the del Bellhop( ) in Eq. 1 and the b() in Eq. 8 should be given. 

5. In the simulation results, as in Fig. 5, more numerical results should be analyzed.

6. Future work should be added in as an independent paragraph at the end of the conclusions.

Comments on the Quality of English Language

 The language of the article needs improvement, as in Line 23, 32, 449.

Author Response

Thank you for the reviewers’ comments concerning our manuscript entitled “A Throughput Performance Analysis Method for Multi-mode Underwater Acoustic Communication Network Based on Markov Decision Process” (remotesensing-3047225). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our research. We have studied the comments carefully and have made corrections which we hope meet with approval. Revised portions are marked in red on the paper. The main corrections in the paper and the responses to the reviewer’s comments are as flowing

Point 1: In the abstract, the authors should address the novelty and improvement of the proposed scheme and shorten the statements for the research background. And the numerical results are suggested to be provided in the abstract to verify the effectiveness of the proposed scheme.

Response 1: As the Reviewer suggested that we have made some changes to the abstract. The revised summary is shown below.

The details are shown in the table below

Serial number	goal	Original content	Modified content
1	Address the novelty and improvement of the paper method	This paper takes into account the actual transmission capabilities at the physical layer and proposes a decoding conflict model to support concurrent transmission scenarios. Furthermore, an analysis model for evaluating performance in multi-mode underwater acoustic networks is established to determine throughput performance limits that align with real-world underwater acoustic environments	Line 15, “This paper investigates the multimode communication of the physical layer, considering factors such as the marine environment, the node transmitting sound source level, and the transmitting distance. A decoding conflict model is proposed to support multimode concurrent transmission scenarios. The communication mode is designed to be compatible with the channel and node characteristics. Additionally, using a Markov decision process, this paper establishes a performance evaluation and analysis model for multimode underwater acoustic networks to determine throughput performance limits in real underwater environments.” is added.
2	shorten the statements for the research background	Delete ”The presence of a large propagation delay significantly impacts the performance of underwater acoustic communication networks. However, recent studies have indicated that the adoption of optimal transmission scheduling can result in the exploitation of propagation delays to significantly increase throughput. Nevertheless, existing research and analyses have often oversimplified the physical layer communication process and assumed uniform transmission capabilities for all task nodes, making it challenging to directly apply these findings to multi-mode underwater acoustic networks.”	Line 13, “Current performance analysis methods are primarily applied to single-mode networks and assume uniform communication capability across all nodes, making them unsuitable for multimode networks.” is added.
3	Provide numerical results	Through simulations across various scenarios, we validate that the throughput performance limits obtained using our proposed method are more accurate within multi-mode networks than previously achieved	“Simulations across various scenarios validate that the throughput performance limits obtained by this method are more accurate under multimode networks, with an improvement in accuracy of over 67.5% compared to existing methods.” is added.

 

Point 2: The language of the article needs improvement, as in Line 23, 32, 449.

Response 2: We were really sorry for our careless mistakes. Thank you for your remind. We have corrected this problem in the original text and rechecked the original text.

Change the original 23 lines to “Simulations across various scenarios validate that the throughput performance limits obtained by this method are more accurate under multimode networks, with an improvement in accuracy of over 67.5% compared to existing methods.”

Change the original 32 lines to " This technology has been extensively applied in marine resource exploitation, marine environment monitoring, and related fields[4–6]. As a result, this topic has emerged as a significant area of research."

Change the original 449 lines to “We have conducted simulations to demonstrate that considering the differences in the communication capabilities of different links can lead to more accurate throughput limits for multimode networks.”

Point 3: In the introduction, more related work are suggested to be provided for comparison so as to address the novelty of the paper.

Response 3: As suggested by the  reviewer, we have checked the literature carefully and added more references to support the novelty of the paper. This is shown in the following table

Serial number	Newly added articles		Related content	Relationship with our manuscript
	New article title	Time of public-ation
1	15: An Adaptive Multi-Mode Underwater Acoustic Communication System Using OSDM and Direct Sequence Spread Spectrum Modulation	2021	Adaptive choice of communication mode according to the SNR	In this paper, the optimal performance of the whole network is not considered, only the optimal transmission performance of the node itself is considered. As a comparison, we analyze the optimal network performance.
2	19: Throughput Performance of Half-Duplex Underwater Acoustic Communication Network	2017	The network performance is analyzed based on the different packet sizes of different nodes	The analysis process does not take into account the physical layer transmission characteristics, resulting in inaccurate results. As a comparison, we re-model the performance of the multi-system underwater acoustic network, which not only considers the transmission characteristics of each node in the physical layer, but also analyzes the transmission requirements of the application layer and other factors
3	20 A new acoustic channel interference model for 3-D underwater acoustic sensor networks and throughput analysis	2020	used the signal-to-noise ratio to describe whether the physical layer underwater acoustic communication signal is successfully received	These papers describe interference conflicts with a fixed SNR. In contrast, we propose a decoding conflict model to describe the conflict, which takes into account the factors of Doppler, multipath and decoding algorithm, so the interference conflict description will be more accurate.
4	22：A Distributed Scheduling Algorithm for Underwater Acoustic Networks With Large Propagation Delays	2021
5	23 Joint Channel and Power Assignment for Underwater Cognitive Acoustic Networks on Marine Mammal-Friendly	2023

 

 

Point 4:The format for S_j,t should be unified. And the details of the del Bellhop( ) in Eq. 1 and the b() in Eq. 8 should be given. 

Response 4: In lines 121 to 126 of the original manuscript, the format of S_j,t  is not consistent. We are very sorry for our negligence. We have corrected this problem in the original text and rechecked the original text.

In formula 1,  represents the propagation delay calculated by the Bellhop model under the current environment and network node location. Bellhop model is a mathematical model used to describe underwater sound field, which can calculate propagation time, energy attenuation and other characteristics by means of search. There are many influencing factors in the process of analysis, which cannot be directly described by analytical expression. The related literature of Bellhop model is added to the reference literature 26, which introduces the use method of Bellhop in detail.

In formula 8, The coupling relationship of input factors in  is complex and cannot be described by analytical expression. The output value of b() is obtained by Monte Carlo simulation. In line 10, an explanation is added.

 

Point 5: In the simulation results, as in Fig. 5, more numerical results should be analyzed.

Response 5: As suggested by the reviewer, we have added more numerical results in figure 5. We also added numerical analysis in Figures 6 and 8.

Serial number	Figure	Increased numerical analysis results
1	5	When comparing the throughput performance limits under different sound source levels, the results of the two methods are similar for small and large sound sources. The largest disparity between the two methods appears when the sound source level is 179 dB, at which point the method proposed in this paper achieves a 1.5 kbps per slot higher throughput compared to the method in [16]. On average, the performance is improved by 68%.
2	6	The propagation loss under hydrologic condition 1 is 0.48 dB and 1.31 dB smaller than that under hydrologic conditions 2 and 3, respectively.
3	8	Similar to Figure 5, the throughput results under different hydrological conditions are consistent for smaller and larger sound source levels. This is because when the sound source level is large enough, all links support multimode communication, whereas when the sound source level is small, no communication is possible. The maximum difference between the throughput upper limits of the three hydrologic conditions is 0.5 kbits/slot. Compared to the traditional method, the average throughput performance is improved by 67.5%, 78.3%, and 67.5%, respectively, under the three hydrological conditions.

 

Point6:  Future work should be added in as an independent paragraph at the end of the conclusions.

Response 6: As suggested by the reviewer, we have supplemented the future work plan in lines 503 to 511.

Thanks to the professional comments again that point out the above problems. The authors hope these explanations would answer your doubts.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The article is devoted to an urgent topic and contains important results. The reviewer has a number of questions and comments: 1. Although the problem statement is very relevant, the article lacks experiments. The results can be improved by analyzing and comparing the results of the proposed method and similar ones with each other. 2. Are there other complex network topologies where the proposed method could be equally useful? 3. Have studies been carried out under real conditions in water? If not, do the authors plan to do so?

Comments on the Quality of English Language

Minor editing of English language required

Author Response

Thank you for the reviewers’ comments concerning our manuscript entitled “A Throughput Performance Analysis Method for Multi-mode Underwater Acoustic Communication Network Based on Markov Decision Process” (remote sensing-3047225). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our research. We have studied the comments carefully and have made corrections which we hope meet with approval. Revised portions are marked in red on the paper. The main corrections in the paper and the responses to the reviewer’s comments are as flowing

Point 1: 1. Although the problem statement is very relevant, the article lacks experiments. The results can be improved by analyzing and comparing the results of the proposed method and similar ones with each other.  

Response 1: The authors agree with the reviewer that the experimental results would be useful to understand. Underwater acoustic network experiment needs a lot of equipment, manpower and funds, we do not have the conditions to carry out underwater acoustic network experiment at sea. However, we have started to prepare the relevant experiments of the paper, and we plan to carry out the verification and improvement experiments related to the content of the paper next year.

   The results of comparison with the method in reference [16] are added in Figure 8, and related explanations are given.

Point 2: 2. Are there other complex network topologies where the proposed method could be equally useful?

Response 2: The throughput model of multi-mode network based on Markov decision process proposed in this paper can be applied to complex environment and complex network topology. However, if the number of network nodes is large or the maximum transmission distance is large, the scale of state matrix and action matrix will be very large, and the solution algorithm based on the combination of dynamic programming and greedy algorithm proposed in this paper will not be realized. At this time, the paper plans to improve the solution method and propose a new method to meet the application needs of any network topology and the farthest transmission distance.

Point 3:3. Have studies been carried out under real conditions in water? If not, do the authors plan to do so?

Response 3: The content of this paper is proposed for the first time and has not been verified in the real Marine environment. We plan to carry out experimental verification and improvement of the content of this paper next year.

In line 503, the paper adds the prospect of the next work, including the future experimental verification and the study of the solution method under the complex network topology.

Thanks to the professional comments again that point out the above problems. The authors hope these explanations would answer your doubts.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

The authors shold compare the performance of the proposed method with other methods.

 

What's purpose of the figure 5?

In algorithm 1, for step 4, why does obtain the optimal policy when pi' is equal to pi?

In algorithm 2, "Calculate the throughput of X (u ) according to the formula (12)"， however, we can not get the X(u) from (12).

In algorithm 2, if M(u) is X(u), why does use two variable?

What's mean the sentence "Figures should be placed in the main text near to the first time they are cited" in the caption of fig. 5?

What is mean the phrase " signal dry-noise ratio "?

In page 5, the sentence "If the bit error rate of receiving node 𝑖 exceeds a certain threshold, then node 𝑖 can successfully receive data packets from node 𝑗"  should be the BER lower a certain threshold.

Comments on the Quality of English Language

The presentation of the manuscript should be improved.

Author Response

Thank you for the reviewers’ comments concerning our manuscript entitled “A Throughput Performance Analysis Method for Multi-mode Underwater Acoustic Communication Network Based on Markov Decision Process” (remote sensing-3047225). We are sorry for our carelessness. Based on your comments, we have made the corrections to make the word harmonized within the whole manuscript. The manuscript has also been checked and revised by a professional English essay polishing agency.

Point 1: What's purpose of the figure 5?

Response 1: We have reordered the drawings in the manuscript so that Figure 5 in the original manuscript becomes Figure 6. Part (a) of the figure is the sound velocity profile of the simulation process, and (b) is the propagation loss under the current sound velocity profile. These two parts are related to the results of section 4.3 below. The purpose of this diagram is to make the simulation parameters clearer.

 

Point 2: In algorithm 1, for step 4, why does obtain the optimal policy when pi' is equal to pi?

Response 2:  pi' is the strategy obtained in the current iteration, and  pi is the strategy obtained in the last iteration. The iterative solution method based on the combination of greedy algorithm and dynamic programming algorithm has the same iteration termination condition as the strategy obtained in the last two iterations. In algorithm 1, when  pi'= pi, it means that the strategy obtained by the last two iterations is the same, and the termination condition is satisfied, and the algorithm reaches the final state of convergence.

 

Point 3: In algorithm 2, if M(u) is X(u), why does use two variable?

Response 3: In algorithm 2，M(u) is the throughput of X(u). X(u) is the scheduling matrix of the network, M(u) is the throughput calculation result and they are not the same.

 

Point 4: What's mean the sentence "Figures should be placed in the main text near to the first time they are cited" in the caption of fig. 5?  What is mean the phrase " signal dry-noise ratio "?

Response 4: Thanks for your careful checks. We are sorry for our carelessness.  "Figures should be placed in the main text near to the first time they are cited" is the content of the paper template, which we forgot to delete due to our carelessness. This has now been removed in Figure 5.

 " signal dry-noise ratio " is a wrong way of writing, which has been corrected to " signal to interference plus noise ratio " in the original text.

We conducted a detailed examination of the full text and found a professional polishing agency to check and revise the paper.

 

 

Point 5: In page 5, the sentence "If the bit error rate of receiving node ? exceeds a certain threshold, then node ? can successfully receive data packets from node ?"  should be the BER lower a certain threshold.

Response 5: We are sorry for our carelessness again. There is a representation error here, which has been corrected in the new manuscript.

Thanks to the professional comments again that point out the above problems. The authors hope these explanations would answer your doubts.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

All my concerns have been addressed.

Reviewer 3 Report

Comments and Suggestions for Authors

The comments of the first round review are responded.

Comments on the Quality of English Language

The writtings have been improved.