A Realistic, Flexible and Extendible Network Emulation Platform for Space Networks

Round 1

Reviewer 1 Report

This paper presents a space network emulation platform that has to be focused on innovating a series of key networking technologies and protocols because of its differences compared to terrestrial networks. In order to pursue the three objectives: authenticity, extendibility and flexibility, the platform must be built on 4 levels.

The information in this paper is well presented and structured. The document contains mathematical equations and computer science concepts that could be hard to understand for someone with no background in the field. the pictures are big enough and help in the process of understanding the concepts. Fig. 5 a) should update the caption "Geometry of Ground Statio..." I would suggest increasing the space between the figure description and the rest of the text and centering all the pictures in line with the text.

The article presents an emulation platform for testing the behavior of specific space networks architectures. Space networks start to become bigger and more complex. In order to facilitate research and make relevant testing at the lab level a platform formed from 4 planes is proposed. After the initial introduction, current solutions for simulating space networks are presented and weak areas that are addressed by the paper are highlighted. With the context set, the actual architecture of the  platform is described, one layer at a time. An example of the use of the platform is presented and some data is discussed. In the end conclusions are drawn.

While an actual problem, the proposed solution is presented in a context where many others such solutions already exist. That being said, the design of the platform (while not necessarily very novel) is a strong one, and it opens the way for future research directions, but it focuses too much on classical theoretical aspects.

The overall structure of the paper is excellent, hitting all the important aspects of an article. The fonts used are appropriate, the language is clear and ideas are well connected one with another. The data offered is relevant to the subject discussed. Too little emphasis is put on the innovative aspects of the paper. While the solution is presented in detail, the problems that it addresses, that are not addressed by the state of the art, are only glossed over at the beginning, with too little mention later on. For example, classically, virtualization can’t offer a large domain of testing scenarios from a hardware perspective, being able to help in identifying major points of failure that would appear in 100% of real life cases, but more elusive problems, that might appear only sometimes (and that are a much bigger problem in larger, complex, systems) aren’t so well detected. How the proposed solution addresses that is not made clear.

More emphasis on the innovative elements should be put either in the beginning where a birds eye view of the architecture is presented, making it clear where those innovations lay in the design (with references later on in the more detailed descriptions), or these elements should be more clearly highlighted in sections III and IV.

The references should be more updated (i.e. 2020-2022) and include more details about 5G and practical use cases, for example white spaces:

- Lin, Xingqin, et al. "5G from space: An overview of 3GPP non-terrestrial networks." IEEE Communications Standards Magazine (2021).

- Martian, Alexandru, et al. "Access to RF white spaces in Romania: Present and future." Wireless Personal Communications 87.3 (2016): 693-712.

- Stancu, Alexandru L., et al. "A comparison between several software defined networking controllers." 2015 12th international conference on telecommunication in modern satellite, cable and broadcasting services (TELSIKS). IEEE, 2015.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper provides an approach to develop a laboratory testing platform for the fundamental problems with the SN and its applications. Based on SDN and virtualization technologies, the proposed platform has an extensible network emulation architecture, and owns the ability to extend a large-scale emulation with less costs. The work is very good. However, it can be improved by:

Check English mistakes

Add a comparison table between different tools.

Improve presentation few figures are out of margins 

Extend conclusions with numerical resultats and with similar works (state of the art)

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

The authors focus their study on the space networks and they introduce the design of an emulation platform that can support a realistic, flexible, and extensible experimental environment to support the study in space networks.

The manuscript is overall well written and easy to follow and the authors have well thought out their main contributions. The provided discussion and analysis of the design of the emulation platform is detailed and concrete.

The authors should consider the following suggestions provided by the reviewer in order to improve the scientific depth of their manuscript, as well as they need to address the following comments in order to improve the quality of presentation of their manuscript.

Initially, in Section 1, the authors should present the provided related work by using more summative language in order to better identify the research gap in the existing literature and how they aim to address it.

In Section 2, the authors should discuss existing research works that deal with the space networks, such as Ad-Hoc, Mobile, and Wireless Networks: 19th International Conference on Ad-Hoc Networks and Wireless, ADHOC-NOW 2020, Bari, Italy, October 19–21, 2020, Proceedings, mainly discussing and examining their ad hoc nature.

In section 4, the authors should include an additional subsection providing the implementation cost of the design of the proposed relation platform, as well as, they need to discuss its computational cost in order to perform the emulations.

In Section 5, the authors should provide a comparative analysis discussion in order to showcase the drawbacks and benefits of the proposed platform compared to the state of the art.

Finally, the overall manuscript should be checked for typos, syntax, and grammar errors in order to improve the quality of its presentation.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

The authors have addressed the reviewers' comments.