Real-Life Traffic Data Based ITS-G5 Channel Load Simulations of a Major Hungarian C-ITS Deployment Site
Round 1
Reviewer 1 Report
Although it is very interesting to read the study cases developed and carried out in real-life v2x pilot and SUMO/OMNet simulation platform. I found several minor issues as follows.
1. Throughout, the term "Vehicle-to-Anything (V2X) communication" and "Vehicle-to-Everything (V2X)" should be consistant.
2. In Introduction, "especially in work zones – therefore, besides fixed R-ITS-S stations, 40 maintenance vehicles were equipped with mobile roadside units (RSU), ", do you mean the onbord unit (OBU) instead? If it is mobileRSU, what is the difference between fixed RSU and mobile RSU?
3. Throughout, the "ITS-G5" is not sufficiently explained.
4. I would like to suggest authors to extensively introduce the fully Day 1 and Day 2 C-ITS services in details. Also, the v2x payload messages have not mentioned in this work, therefore, it is hard to judge whether the capacity of v2x network would be able to support transmitting the messages between each v2x users devices.
Author Response
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Reviewer 2 Report
1. After reading your abstract one cannot have an idea on what problem do you want to solve ? what are the problems ? what did you find ?
2. I cannot see clearly what is your contribution ? what is the aim of this study ?
English part is ok.
Author Response
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Reviewer 3 Report
In this work, real-world traffic and map data of a C-Roads harmonized major Hungarian C-ITS deployment site are used to simulate the effects of various ITS-G5-based C-ITS services and V2X penetration rates on the Channel Busy Ratio (CBR) parameter of the radio access environment. The C-ITS infrastructure of the Budapest Ring Road (expressway M0) and simulated V2X messaging of cooperative services using real-world traffic data measurements in the implementation is modeled. The paper is well organized, and the contributions are sufficient for publication. I only have some small suggestions regarding the presentation of the work:
1) The quality of the figures can be improved. The existing ones such as figures 4-7 are a little blurry. Please also differentiate the curves through types of lines as well instead of just using color.
2) The abstract can be improved. Most of the context has been used to introduce the background. Please reduce the background information and enrich the context of what has been done in this work.
3) Please incorporate some most recent literature about the connected automated vehicles data collection and data processing algorithms to have the real trajectory data of the connected automated vehicles into either the introduction section or traffic data section as these data will be useful to model the interaction between the connected automated vehicles. The works include an automated driving systems data acquisition and analytics platform; hydro-3d: hybrid object detection and tracking for cooperative perception using 3D lidar; autonomous vehicle kinematics and dynamics synthesis for sideslip angle estimation based on consensus kalman filter; automated vehicle sideslip angle estimation considering signal measurement characteristic.
4) Please elaborate more on the caption of the figures for example Figure 3.
5) Please consider adding a pipeline or framework diagram into the paper for the reader to better understand the work.
Author Response
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Reviewer 4 Report
Authors comments
1. In section 2, explain if you used the Artery framework and their main components as the main tool in your simulation proposal.
2. When you talk about three unlimited variables contained in the simulation, it is not clear which was the second.
3. Figure 2 is difficult to interpret, please explain what is graphed on each axis and try a more visual way to understand the information displayed. If this is not possible, please provide a more detailed explanation about it.
4. It is convenient to elaborate on the meaning of figure 3 and briefly explain the traffic calculation process (expand the explanation given). Any comments on the accuracy of the method used to calculate traffic flow?
5. When you mention that the first section of the matrix (Equation 1) represents the number of vehicles that enter and pass after a driveway is equal to the number of vehicles at the next measurement point, don't you consider the vehicles that might stay at the intermediate points? at the entrance and exit?
6. What do the three figures in the first section one of the matrix represented as equation 1 represent?
7. In light of your previous answer, explain in detail the meaning of the right-hand side of the matrix system.
8. intrinsically, equations (2), (3) and (4) do not represent a mathematical model of integer programming
9. It is suggested to use the word equation processor or write your document in latex to unify the meaning of the variables used.
10. The objective function of model 4 is a convex function in x, therefore the minimum exists and is unique. How do you use the regularization parameter? what is it for?
11. Algorithm 1 is the heuristic mentioned at the beginning of your document?
12. It is not clear to me how the entire nonlinear programming model intervenes in the simulation model. please be more explicit
A thorough review of the spelling and style of the document is suggested
Author Response
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Round 2
Reviewer 2 Report
Summarizing the conclusion section of the article into several points and clarifying them clearly.
Simplify English expression as much as possible.
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Reviewer 4 Report
1. Authors are advised to clearly define a section for the introduction of the document and a section for the background.
2. It is also recommended to use the Word equation processor to write models (2), (3) and (4)
3. It would be desirable to make a correct separation of the syllables at the end of a line.
The style and spelling of the English language improved substantially. As a last recommendation, it is suggested to make the correct cut of syllables at the end of the lines that require it.
Author Response
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