Research on Key Technologies of Elastic Satellite Optical Network Based on Optical Service Unit

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The article is well written and the text flows in a way that is easy to follow; however, it lacks a clear focus, which complicates the reader’s understanding of the authors’ main contribution. Upon finishing the paper, I was left wondering what the authors aimed to achieve with this work, an indication of the aforementioned lack of clarity. 

Although the authors outline the article’s contributions in the final paragraph of section 1 the characteristics mentioned (e.g. deterministic quality-of-service, guaranteed bandwidth allocation, bounded latency transmission, fault-tolerant reliability, and cryptographic) are not supported convincingly throughout the text. The mentioned attributes are neither evident in the formulation/methodology/proposal nor in the results of the study. 

There appears to be a disconnection between the article’s title, the listed contributions, and the written proposal itself, these elements do not align coherently. 

The paper lacks a section that adequately reviews the relevant literature, which further complicates efforts to identify its specific contributions. 

From what I could interpret, the authors are proposing a new layered architecture for the network. If that is the case, I would expect a more in-depth investigation of the implications of this new stack, which is not delivered in the current version. 

The explanation of the experimental setup is also unclear, specifically, it is difficult to understand how the setup in Figure 5 is used to emulate the architecture shown in Figure 4, or how satellite links are emulated in this configuration (Fig. 5). 

Finally, several results are presented using digital signal plots (e.g., Figure 6), but the accompanying explanations are insufficient, making it hard to follow the authors’ reasoning and the conclusions drawn from these figures.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The following is the detailed comments and suggestions:

The manuscript proposes optical service unit-based optical inter-satellite links (OISL-OSU) to overcome current limitations in fine-grained service bearing. This approach is particularly significant for optical transport networks (OTNs), which serve as the backbone for many communication infrastructures. Through experimental validation, the authors demonstrate that OISL-OSU achieves improvements in transmission delay, resource utilization efficiency, and hard-pipe connection capabilities. The proposed enhanced fine-grained optical transport network (fgOTN) is shown to be more efficient in utilizing network resources and applicable to various satellite optical network topologies, including those in inclined geosynchronous orbit, medium earth orbit, low earth orbit, and both user and network interfaces (Fig. 4).

The topic is relevant and timely, addressing a gap in the development of 6G networks—particularly in enhancing hard-channel communication, deterministic delay, and reliability. The experimental results support the claim that OISL-OSU aligns well with these emerging requirements, potentially becoming a core transmission technology for future 6G space-terrene-sea integrated networks and industrial internet applications.

Compared to existing solutions, the manuscript contributes by providing a detailed implementation setup (Fig. 5(a)) and by benchmarking OISL-OSU against OISL-235 MPLS. The experimental data indicates that OISL-OSU outperforms the latter in bandwidth utilization, delay, jitter, and burst processing performance.

Methodologically, the paper presents several performance evaluations:

Fig. 10 demonstrates that OISL-OSU is well-suited for time-sensitive business scenarios.

Fig. 11 shows that OISL-OSU reduces jitter by up to 75% across different frame lengths (68B to 1522B), with consistent improvements over OISL-MPLS.

Fig. 12 highlights significant reductions in average burst frames, with improvements exceeding 80% across the same range of frame lengths.

The conclusions are consistent with the presented evidence and align well with the research questions posed. Experimental validation from Figures 6 to 12 substantiates the claims and is adequately summarized in the conclusion section.

The references cited are appropriate and relevant to the study. Additionally, the figures are clearly presented and effectively support the evaluation of OISL performance, following common assessment criteria in this domain.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This is a good paper and has potential for publication; however, several issues need to be addressed to improve its clarity and overall quality:

-The figures are dense and would benefit from simplified annotations and clearer legends. Some figures also require more detailed explanation within the text.
-Acronyms should be defined the first time they appear in the document to ensure clarity for all readers.
-While the section structure is generally well organized, it would benefit from intuitive subheadings to guide the reader through key technical aspects such as encoding, multiplexing, and performance optimization.
-Consider using more schematic diagrams or flowcharts to clearly illustrate protocol stacks, encapsulation processes, and frame transitions.
-Although relevant references are included, the literature review is brief. It should be expanded, especially in relation to optical inter-satellite networking and 6G architectures, with updated references to recent works.
-The paper should clearly state its novelty, particularly in comparison to M-OTN and other existing OTN enhancements.
-While formulas and derivations are provided, some lack sufficient explanation. These should be better contextualized, ideally with examples or step-by-step walkthroughs.
-The paper should address potential scalability challenges, such as resource allocation, FEC overhead at scale, and cross-orbit traffic scheduling.
-Please include a quantitative analysis of key performance metrics, especially latency, as it is a critical factor for time-sensitive satellite communication systems.

Author Response

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Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

I generally felt the manuscript was well written, well-organized, and made a cohesive presentation of how the approach could potentially improve the performance of data transfer between the nodes of a multi-layer network with space-based assets, particularly where, in such a network, the availability of nodes can vary and the quality of the optical channel can vary with time (i.e. weather, turbulence, line-of-sight). Works such as that provided in the article are important for exploring different methods for making such networks more reliable and improving throughput. I appreciated that the authors included some hardware-in-the-loop elements to add more realistic components in the system, rather than completing the analysis entirely by simulation. Too many of the current articles I read are simulation based and struggle to accommodate some of the challenges and limitation imposed by physical hardware and channels.

My one and only criticism of the manuscript is the font sizes in some of the figures (Figures 4, 6, 7, and 8 specifically). If there is a way to make the text in these figures more readable without needing to use a Zoom feature online, it would be most helpful.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

After the authors make the necessary changes, it is ready to be published.