The Analysis of Resource Efficiencies for the Allocation Methods Applied in the Proposed OAM&WDM-PON Architecture

Round 1

Reviewer 1 Report (Previous Reviewer 2)

Comments and Suggestions for Authors

For detailed reference, please refer to the attachment.

Comments for author File: Comments.pdf

Author Response

Round 1 - Reviewer #1:

Manuscript Summary

This manuscript proposes a novel OAM&WDM-PON network architecture with a P2MP topology and three resource allocation methods (static, dynamic, dynamic customized) to minimize working wavelengths and OAM channels while meeting user bandwidth requests. The approach leverages MATLAB-based simulation to evaluate resource efficiencies (e.g., channel utilization ηη and savings σσ) for standalone WDM, standalone OAM, and hybrid OAM/WDM operating technologies.

I appreciate the Reviewer’s opinion, comments and remarks. Detailed responses are provided below. Changes made to the article are highlighted (a red color). I'd like to thank the respected Reviewer for his comments and remarks that make this paper better.

 

Here, publication could be possible after addressing the following revisions:

Major Revisions Required

1. Literature Context and References

The background section adequately introduces OAM/WDM basics but omits critical recent advances (e.g., 2023–2024 OAM-PON experiments). Revise by:

o Adding comparisons with PD-NOMA-OAM systems (Shukla & Gupta 2023, Ref. 11) and MIMO-FSO integrations (Singh et al. 2023, Ref. 10).

o Discussing alignment/divergence with ITU-T standards (e.g., G.989.3for 40G-PON wavelength allocation).

Response: I appreciate the Reviewer’s comments. The comments are accepted; the State-of-the-art section is arranged. Also, the Discussion section is added where results are discussed in detail and other published works and ITU-T standards are appropriately referred.

 

2. Experimental Design and Validation

The simulation-only methodology lacks real-world validation. Revise by:

o Incorporating practical constraints (e.g., OAM crosstalk noise based on §2’s MIMO compensation; SLA-driven cost models for operators).

o Benchmarking against existing PON resource allocation schemes (e.g., DBA in XGS-PON).

Response: I respect the Reviewer’s comments. A simulation model is determined for analyzing and evaluation of considered allocation methods primarily. Mentioned practical constraints can be incorporated into this model at its future extension. In the Discussion section, existing PON resource allocation schemes are also appropriately referred.

 

3. Clarity of Results Presentation

Figure 3 (efficiency comparison) is qualitative and lacks numerical evidence. Revise by:

o Replacing schematic plots with quantitative bar charts (e.g., ηCh-WDMηCh-WDM values with error bars for 16/64/256 ONUs).

o Adding a table summarizing statistical significance (e.g., p-values for dynamic vs. static methods).

Response: I respect the Reviewer’s comments. In this manuscript, I selected a presentation of output parameters for the number of ONU units equal to 16 (Section 5). Results for higher numbers of ONU units can be involved in the next contribution. For presented development environment and real network traffic loading, there is considered no statistical hypothesis.

 

4. Technical Justification and Discussion

Key assumptions (e.g., zero OAM interference in simulations) weaken conclusions. Revise by:

o Quantifying how OAM crosstalk impacts dynamic allocation efficiency (e.g., "At 15 dB crosstalk, ηCh-OAMηCh-OAM drops by 18%").

o Analyzing SLA feasibility (e.g., cost per SLA level via operator expenditure models).

Response: I respect the Reviewer’s comments. A simulation model is determined for analyzing and evaluation of considered allocation methods primarily. OAM channels are considered in operation, e.g. OAM crosstalk impacts are not destructional. Mentioned OAM crosstalk impacts can be incorporated into this model at its future extension. The SLA feasibility can be analyzed only with the operator. In this manuscript, it is not its aim.

 

5. Algorithm Implementation Details

Inconsistent pseudocode formatting hinders reproducibility (e.g., mixed "EndIf"/"End If"). Revise by:

o Standardizing pseudocode syntax (§4.1–4.3) and fixing terminology errors (e.g., "auxilliary" → "auxiliary" in §3.4).

o Clarifying hyperparameter selection (e.g., why SLA=1–6? How was 50 GHz default channel spacing chosen?).

Response: I respect the Reviewer’s comments. I agree some typing errors can be present in the manuscript. I hope that they are eliminated in this version of the manuscript. The SLA values from 1 up to 6 are provided by the operator. The default 50 GHz channel spacing is established by the standard ITU-T G.694.1.

 

 

 

Additional Recommendations

• Extend validation: Test dynamic methods under traffic bursts (e.g., using real GPON traces from Fig. 2).
• Discuss limitations: Address scalability of OAM channels beyond 16 modes (e.g., vortex fiber constraints in §3.3).
• Enhance figures: Label axes in Fig. 1 (signal flow) and Fig. 2 (time units for GPON load).

Response: I respect the Reviewer’s comments. Additional recommendations can be incorporated into this model at its future extension. A signal flow is added into Fig. 1. In Fig. 2, the flow of real GPON network traffic loading is displayed as imported from the real GPON OLT terminal. Time units are at their disposal from the GPON OLT workplace.

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

In this manuscript, the authors give the analysis of resource efficiencies for the allocation methods applied in the proposed OAM&WDM-PON network architecture. These WDM and OAM channel allocation methods are oriented towards minimizing a number of working wavelengths and OAM channels that will be used for compliance of customers’ requests for data transmitting in the proposed point-to-multipoint OAM&WDM-PON network architecture. For analyzing and evaluation of considered allocation methods, a simulation model related to the proposed P2MP OAM&WDM-PON network design realized in the MATLAB programming environment is presented with acquired simulation results. Finally, resource efficiencies of the presented novel allocation methods are evaluated from a viewpoint of application in future OAM&WDM-PON networks. I don't think this manuscript is ready yet. Therefore, I cannot recommend the publication of this manuscript.

1. The first and most core issue is that the author seems not to have prepared this manuscript well. There are a great many revised contents marked in red in the manuscript.
2. The same Figure 2 appears twice and the data is very blurry.
3. A large number of algorithms appeared in the manuscript. It doesn't look like an article but a technical report.

Author Response

Round 1 - Reviewer #2:

In this manuscript, the authors give the analysis of resource efficiencies for the allocation methods applied in the proposed OAM&WDM-PON network architecture. These WDM and OAM channel allocation methods are oriented towards minimizing a number of working wavelengths and OAM channels that will be used for compliance of customers’ requests for data transmitting in the proposed point-to-multipoint OAM&WDM-PON network architecture. For analyzing and evaluation of considered allocation methods, a simulation model related to the proposed P2MP OAM&WDM-PON network design realized in the MATLAB programming environment is presented with acquired simulation results. Finally, resource efficiencies of the presented novel allocation methods are evaluated from a viewpoint of application in future OAM&WDM-PON networks. I don't think this manuscript is ready yet. Therefore, I cannot recommend the publication of this manuscript.

I appreciate the Reviewer’s opinion. After reading the comments, I think there is a big misunderstanding probably. At the re-submission, there is a demand for two files – the revised manuscript and the revised manuscript with highlighted changes.

1. The first and most core issue is that the author seems not to have prepared this manuscript well. There are a great many revised contents marked in red in the manuscript.

It seems that the Reviewer worked with a previously revised version of the manuscript where changes were tracked in the docx file. If all changes are accepted, then the final revised manuscript will be finished.

1. The same Figure 2 appears twice and the data is very blurry.

There is also a change in Fig. 2 comparing to the previous version – from 96 dpi resolution up to 600 dpi resolution concretely. After accepting this change, then only one Fig. 2 will be present.

1. A large number of algorithms appeared in the manuscript. It doesn't look like an article but a technical report.

I appreciate the Reviewer’s opinion. Generally, algorithms differ in types of the PON network and above all in allocation methods. For their clear definition and interpretation, they are presented separately if possible and meaningfully. These algorithms are trained in the simulation model where different channel allocation methods can be analyzed.

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

Dear Author,

the manuscript deals with the efficiency of resource allocation methods in a proposed OAM&WDM-PON (Orbital Angular Momentum & Wavelength Division Multiplexed Passive Optical Network) network architecture.

 

I suggest adding the sentence "The paper is organized as follows:" as a new paragraph to clearly introduce the paper structure.

Line 130: The author uses "we are focusing," but since there is only one author, this should be corrected to "I am focusing" or rephrased in a passive voice.

The Introduction section should be split into two separate sections: "Introduction" and "State of the Art."

I highly appreciate that the author systematically compares several allocation methods and provides quantitative results along with clear conclusions.

The use of real traffic data from a Slovak telecom operator significantly enhances the practical relevance of the simulations.

Please use only vector graphics for all figures to improve their quality and readability.

Lines 226 and 227: There is a typographical error; the hyphen ("-") should be replaced with an dash ("–").

Please use decimal points instead of commas in numerical values.

The description of the algorithms should be supported with diagrams. While it is not necessary for every algorithm, including diagrams for some of them would be beneficial. Additionally, the definitions of parameters could be presented in a table for better clarity.

The paragraph beginning on line 552 should be included in the discussion of results, not in the conclusions section.

Figure 3 is of very low quality and should be improved.

I recommend that the author consider including additional references, particularly recent publications in the field of OAM-PON and resource allocation in optical networks, to further strengthen the background and state-of-the-art sections of the paper.

10.1109/ICRITO61523.2024.10522168, 10.1109/ICACIC59454.2023.10435268, 10.3390/electronics9071081, 10.3390/electronics8070762, 10.23919/PS.2019.8817727, 10.1109/OECC54135.2024.10975536, 10.1109/FOAN63517.2024.10765772

 

However, I have several suggestions for improving the paper. The proposed model, which is based on real data, is highly impactful for the research field and will be very welcome in Photonics Journal. Overall, the paper is highly relevant and makes a valuable contribution.

Author Response

Round 1 - Reviewer #3:

Dear Author,

the manuscript deals with the efficiency of resource allocation methods in a proposed OAM&WDM-PON (Orbital Angular Momentum & Wavelength Division Multiplexed Passive Optical Network) network architecture.

I am very pleased to have received Reviewer’s comments and remarks. Detailed responses are provided below. Changes made to the article are highlighted (a red color). I'd like to thank the esteemed Reviewer for his comments and remarks that make this paper better.

 

I suggest adding the sentence "The paper is organized as follows:" as a new paragraph to clearly introduce the paper structure.

Line 130: The author uses "we are focusing," but since there is only one author, this should be corrected to "I am focusing" or rephrased in a passive voice.

The Introduction section should be split into two separate sections: "Introduction" and "State of the Art."

Response: I appreciate the Reviewer’s comments. The comments are accepted; the State of the Art section is arranged. Also, the Discussion section is added where results are discussed in detail and other published works are appropriately referred.

I highly appreciate that the author systematically compares several allocation methods and provides quantitative results along with clear conclusions.

The use of real traffic data from a Slovak telecom operator significantly enhances the practical relevance of the simulations.

Please use only vector graphics for all figures to improve their quality and readability.

Lines 226 and 227: There is a typographical error; the hyphen ("-") should be replaced with an dash ("–").

Please use decimal points instead of commas in numerical values.

Response: I appreciate the Reviewer’s comments. The comments are accepted.

The description of the algorithms should be supported with diagrams. While it is not necessary for every algorithm, including diagrams for some of them would be beneficial. Additionally, the definitions of parameters could be presented in a table for better clarity.

Response: I respect the Reviewer’s comments. For the definitions of parameters, I prefer a way involved in the manuscript – subsections 4.3 and 4.5, where parameters can be presented with more necessary details for more precise presentation and understanding.

The paragraph beginning on line 552 should be included in the discussion of results, not in the conclusions section.

Figure 3 is of very low quality and should be improved.

Response: I appreciate the Reviewer’s comments. The comments are accepted; the Discussion section is added. There is also a change in Fig. 3 – from 96 dpi resolution up to 600 dpi resolution.

I recommend that the author consider including additional references, particularly recent publications in the field of OAM-PON and resource allocation in optical networks, to further strengthen the background and state-of-the-art sections of the paper.

10.1109/ICRITO61523.2024.10522168

10.1109/ICACIC59454.2023.10435268

10.3390/electronics9071081

10.3390/electronics8070762

10.23919/PS.2019.8817727

10.1109/OECC54135.2024.10975536

10.1109/FOAN63517.2024.10765772

Response: I appreciate this Reviewer’s comment. The comment is accepted; the Discussion section is added where results are discussed in detail and other published works are appropriately referred to additional references.

 

However, I have several suggestions for improving the paper. The proposed model, which is based on real data, is highly impactful for the research field and will be very welcome in Photonics Journal. Overall, the paper is highly relevant and makes a valuable contribution.

Round 2

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

Can be published.

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

The author has addressed all of my comments by incorporating relevant annotations and textual revisions into the research paper. I am pleased to recommend that the paper be accepted in its current form.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The article "The Analysis of Resource Efficiencies for the Allocation Methods Applied in the Designed OAM&WDM-PON Network Architecture" proposes an analysis of the efficiency in the use of resources in a passive optical network (PON) architecture based on orbital angular momentum multiplexing (OAM) and wavelength division multiplexing (WDM). The author compares static, dynamic, and customized allocation methods implemented via simulation in MATLAB, aiming to reduce the number of active channels required for transmission. The approach is interesting, as it uses emerging technologies like OAM for optical networks, potentially helping the development of advanced networks.

However, the manuscript must undergo significant improvement. Upon review, I have identified several critical issues that need to be addressed:
a) The manuscript suffers from a lack of clarity and coherence in its writing. Several sentences are grammatically incorrect, excessively long, or poorly structured, making comprehension hard. Some technical terms are introduced without proper definitions, and the general narrative lacks fluidity. Maybe the free service of Grammarly.com or even ChatGPT can help the author improve the text.
b) The pseudocodes in the manuscript are poorly formatted and inadequately explained. Key algorithmic steps are unclear, variable names are not defined, and it isn't easy to understand how the code relates to the simulation results. A thorough reformulation with a more transparent structure and comments is recommended.
c) The methodology section lacks critical detail. Important simulation parameters are missing, such as information on the network topology, traffic models, number of connections, and how resource efficiency was measured. This lack of information significantly limits the reproducibility of the results and undermines the credibility of the evaluation.
d) Although some comparative results are presented, there is a noticeable lack of in-depth analysis. The performance differences between the proposed allocation methods are described vaguely (e.g., stating they are "better in all cases") without rigorous interpretation or benchmarking against related work. Additionally, the results shown in the tables are not adequately discussed.
e) Finally, the manuscript does not sufficiently cite or compare its approach to the recent literature. Several assertions about the novelty and efficiency of the proposed methods are not backed by comparisons to prior work, raising concerns about this contribution's originality and relevance.

Comments on the Quality of English Language

It has been mentioned previously.

Author Response

Reviewer #1:

The article "The Analysis of Resource Efficiencies for the Allocation Methods Applied in the Designed OAM&WDM-PON Network Architecture" proposes an analysis of the efficiency in the use of resources in a passive optical network (PON) architecture based on orbital angular momentum multiplexing (OAM) and wavelength division multiplexing (WDM). The author compares static, dynamic, and customized allocation methods implemented via simulation in MATLAB, aiming to reduce the number of active channels required for transmission. The approach is interesting, as it uses emerging technologies like OAM for optical networks, potentially helping the development of advanced networks.

I am very pleased to have received Reviewer’s comments and remarks. Detailed responses are provided below. Changes made to the article are highlighted (a blue color). I'd like to thank the esteemed Reviewer for his comments and remarks that make this paper better.

However, the manuscript must undergo significant improvement. Upon review, I have identified several critical issues that need to be addressed:
a) The manuscript suffers from a lack of clarity and coherence in its writing. Several sentences are grammatically incorrect, excessively long, or poorly structured, making comprehension hard. Some technical terms are introduced without proper definitions, and the general narrative lacks fluidity. Maybe the free service of Grammarly.com or even ChatGPT can help the author improve the text.

Response: I'd like to thank the Reviewer for a mentioned comment that makes this paper better. The comment is accepted; based on the recommendation, I realized extensive English revisions of substantial parts in the manuscript. I eliminated typing errors and some inaccuracies. I also reformulated any sentences, expressions and formulations to be more accurate. In the revised version of the manuscript, many sentences were shortened and re-written. Definitions of some technical terms were complemented.

In the manuscript, a theme is very extensive and complex (optical networks, multiplexing techniques, allocation methods, resource efficiencies, …). So, it is sometimes difficult to find a simplified verbalization without loss of the meaning. Moreover, I prefer to express main ideas by my words and I’d like to avoid using common English editor services that can change the meaning of the original ideas. Because of the of the manuscript’s originality and the novelty, I try to improve the text in other way.

b) The pseudocodes in the manuscript are poorly formatted and inadequately explained. Key algorithmic steps are unclear, variable names are not defined, and it isn't easy to understand how the code relates to the simulation results. A thorough reformulation with a more transparent structure and comments is recommended.

Response: I appreciate the Reviewer’s comments. The comments are accepted; the pseudocodes are re-formulated and re-written; key algorithmic steps are improved, supplemented and adjusted; variable names are defined in the revised version of the manuscript.

The simulation model is described in Section 3 in details. It is very complex tool for analyzing allocation methods where all its parts (development environment, algorithms with input and output parameters, calculations, …) must be properly processed to acquire desired simulation results. I agree that the full understanding of all these parts is not fast and easy.

c) The methodology section lacks critical detail. Important simulation parameters are missing, such as information on the network topology, traffic models, number of connections, and how resource efficiency was measured. This lack of information significantly limits the reproducibility of the results and undermines the credibility of the evaluation.

Response: I respect the Reviewer’s comments. Mentioned simulation parameters are already present in the manuscript. Concretely, the network topology (Section 2), traffic models (Subsection 3.1), the number of connections (Section 4), and how a resource efficiency was measured (Subsection 3.5).

d) Although some comparative results are presented, there is a noticeable lack of in-depth analysis. The performance differences between the proposed allocation methods are described vaguely (e.g., stating they are "better in all cases") without rigorous interpretation or benchmarking against related work. Additionally, the results shown in the tables are not adequately discussed.

Response: I respect the Reviewer’s comments related to mentioned Subsections 4.1, 4.2 and 4.3. The comments are accepted; enhanced discussions to simulation results shown in tables are added. Based on simulation results, many various interpretations and evaluations can be realized. As an example, a comparison of efficiencies of channel utilization for proposed allocation methods is added in Section 5. A graphical presentation of all realized interpretations and evaluations of simulation results can lead to a massive extension of the manuscript’s volume. Instead, a summary of obtained relevant findings is realized in the Conclusions.

e) Finally, the manuscript does not sufficiently cite or compare its approach to the recent literature. Several assertions about the novelty and efficiency of the proposed methods are not backed by comparisons to prior work, raising concerns about this contribution's originality and relevance.

Response: I respect the Reviewer’s comments. The most related works are included in the Introduction. In this manuscript, a new approach is presented (the proposed OAM&WDM-PON Network Architecture / Wavelength and OAM channel allocation methods), so there are no works with similar results (resource efficiencies and channel savings) to be compared. This evidences the originality and relevance of the contribution. Each part of the Introduction is richly referenced to indicate that the applied research aim of this manuscript is original and there are no known papers suitable for a near comparison. So, the analyses of the resource efficiencies in passive optical networks utilizing the hybrid OAM/WDM multiplexing presents a groundbreaking study.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Please see the attached.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

The quality of English language could be improved to more clearly express the research.

Author Response

Reviewer #2:

This manuscript proposes a hybrid OAM&WDM-PON network architecture with static, dynamic, and dynamic customized resource allocation methods to minimize the consumption of wavelengths and OAM channels in point-to-multipoint passive optical networks. The study evaluates resource efficiencies via MATLAB simulations under 16 ONU scenarios and compares performance across WDM, OAM, and hybrid OAM/WDM technologies. Publication of this manuscript could be possible after addressing the following revisions.

I appreciate the Reviewer’s opinion, comments and remarks. Detailed responses are provided below. Changes made to the article are highlighted (a blue color). I'd like to thank the respected Reviewer for his comments and remarks that make our paper better.

 1. Trade-off between resource efficiency and practicality

The dynamic customized allocation method relies on SLA-based prioritization, but its implementation complexity (e.g., real-time SLA negotiation and resource reallocation) is not thoroughly analyzed. While the authors emphasize resource savings, a discussion on trade-offs-such as latency introduced by dynamic adjustments or hardware compatibility with existing WDM-PON infrastructures-would clarify its practicality for real-world deployment.

Response: I respect the Reviewer’s comments related to the Section 3. This manuscript is oriented on the allocation methods of wavelength and OAM channels in the proposed network architecture. For these allocation methods, the network layer is the main functional layer. Moreover, these allocation methods are analyzed on the proposed OAM&WDM-PON network architecture. For specification, there is no real-time SLA negotiation in the allocation methods. The SLA values are determined before application of allocation methods based on the customer’s contract of service provision.

2. Experimental design and results

Simulation scope: The current results are limited to 16 ONU units. Extending simulations to larger scales (e.g., 256 ONU units) and dynamic traffic patterns (e.g., bursty or time-varying loads) would strengthen the generality of conclusions. Parameter justification: Key parameters (e.g., wavelength range 850–1625 nm, guard time values) need explicit justification based on industry standards or prior experimental studies (e.g., ITU-T G.694.1 for WDM channel spacing).

Response: I appreciate the Reviewer’s comments related to the Section 3. The comments are accepted; key parameters related to the number of WDM channels (Subsection 3.3) were supplemented and improved. Possible extending simulations (larger scales, dynamic traffic patterns) are added to future challenges.

 3. Clarification of allocation algorithms

Mathematical formalism: The algorithms (e.g., Algorithm 1–6) lack formal mathematical definitions. Adding equations for resource allocation objectives (e.g., minimizing wavelengths/OAM channels under SLA constraints) would improve reproducibility. SLA implementation: The mapping between SLA levels (1–6) and resource allocation logic (e.g., bandwidth throttling or priority weights) requires detailed explanation.

Response: I appreciate the Reviewer’s comments related to the Section 3. The comments are accepted; formal mathematical definitions related to resource channel utilization and savings (Subsection 3.5) were added. supplemented and improved. Also, the SLA value specification were supplemented and explained in detail (Subsection 3.3). I must emphasize that there is no real-time SLA negotiation involved in allocation methods.

4. Comparison with related work

While existing WDM-PON resource allocation methods are cited, the manuscript does not directly compare the proposed methods with state-of-the-art approaches (e.g., machine learning-based allocation or TDM/WDM hybrids). A quantitative comparison in terms of wavelength savings, latency, or scalability would highlight the novelty of the hybrid OAM/WDM approach.

Response: I respect the Reviewer’s comments. The most related works are included in the Introduction. In this manuscript, a new approach is presented (the proposed OAM&WDM-PON Network Architecture / Wavelength and OAM channel allocation methods), so there are no works with similar results (resource efficiencies and channel savings) to be compared. This evidences the originality and relevance of the contribution. Each part of the Introduction is richly referenced to indicate that the applied research aim of this manuscript is original and there are no known papers suitable for a near comparison. So, the analyses of the resource efficiencies in passive optical networks utilizing the hybrid OAM/WDM multiplexing presents a groundbreaking study.

The TDM technology separately or in hybrid combinations is involved in future challenges.

5. Further validation

Real-world performance metrics: The simulation focuses on resource efficiency but omits critical physical-layer metrics (e.g., BER degradation due to OAM crosstalk, transmission distance limitations). Adding these would validate the technical feasibility.

Hardware constraints: The impact of passive components (e.g., splitters, filters) on OAM mode purity and wavelength stability should be discussed, especially for dynamic allocation scenarios.

Response: I appreciate the Reviewer’s comments that are very interesting from my viewpoint. This manuscript is oriented on the allocation methods of wavelength and OAM channels in the proposed network architecture. For these allocation methods, the network layer is the main functional layer. For this main aim of this contribution, I realized an appropriate simulation model.

We realized another simulation model (focused on the physical-layer metrics) for the optical layer considerations. The critical optical-layer metrics related to the wavelength multiplexing technique are presented in our previous work [18].

The impact of passive components on OAM mode purity and wavelength stability is discussed in a reference under consideration [21].

6. Visualization of results

The results are presented in tables without graphical interpretations. Including figures—such as bar charts comparing static/dynamic efficiencies, heatmaps for wavelength-OAM channel occupancy, or trendlines for scalability—would enhance readability and impact.

While the integration of OAM and WDM is interesting and aligns with next-generation PON demands, the manuscript requires significant revisions to address methodological gaps, expand experimental validation, and improve clarity. Critical additions include mathematical formalism, scalability analysis, and real-world performance metrics. After thorough revisions, the work could serve as a valuable reference for high-capacity optical access networks.

Response: I respect the Reviewer’s comments. The comments are accepted; enhanced discussions to simulation results shown in tables are added. Based on simulation results, many various interpretations and evaluations can be realized. As an example, a comparison of efficiencies of channel utilization for proposed allocation methods is added in Section 5. A graphical presentation of all realized interpretations and evaluations of simulation results can lead to a massive extension of the manuscript’s volume. Instead, a summary of obtained relevant findings is realized in the Conclusions.

We hope that the respected Reviewer understands this situation and he will agree with this reasoning.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

 

I would like to thank the Author for submitting a revised version of his manuscript and providing detailed responses to my initial concerns. While I acknowledge the effort to improve the work, many of the previously raised issues remain unresolved or only partially addressed. Below, I try to offer a detailed point-by-point analysis of the revision, now supported by direct evidence from the revised text. I hope my comments can help the Author produce a new version of his article.

 

a) Language clarity
What was requested: Improve grammar, sentence construction, and the general readability of the manuscript.
Authors' response: reported performing an extensive manual revision without automated editing tools.
Explaining my comments with evidence: despite some corrections, many expressions remain awkward, grammatically incorrect, or overly vague, like:

Example 1 (Abstract, line 11):
"The orbital angular momentum technique is very perspective for using within passive optical networks…"
Comment: "Very perspective" is ungrammatical; the proper term is "highly promising".

Example 2 (Line 44):
"It can be considered that the OAM deployment is realizable."
Comment: This is overly passive and redundant. That would be clearer: "OAM deployment is feasible with current technologies."

Example 3 (Line 49):
"(...) in the common optical FMF (Few-Mode Fiber) fiber (...)"
Comment: the term fiber is already in the acronym definition, and it sounds strange to repeat it.

Example 4 (Line 120):
"As introduced, it can be interesting to join these two multiplexing approaches."
Comment: Informal and imprecise — scientific writing demands clarity and rigor.

I still encourage the author to use available tools to help improve his English style. I'm not telling the Author to delegate the writing but to be informed about the text suggestions for possible improvements. 

b) Pseudocodes and algorithms

What was requested: Use a formal, recognizable pseudocode structure; define variables and clearly connect them to the simulation.
Authors' response: reported having rewritten the pseudocode and defined variables accordingly.
Explaining my previous comments with evidence: the structure of the algorithms is still informal and confusing, mixing natural language with ambiguous logic. Some examples:

Example 1 (Page 9):
7. If (Are all ONU served?)
8.       Then If (Are there optional functions?)
9.              Then The selection of the optional function And step 1
10.             Else EndIf
11.     Else step 3
12. EndIf

Comment:

• "Else EndIf" and "Else step 3" are nonstandard and syntactically meaningless in structured pseudocode.
• For me, indentation doesn't follow a logical block; in general, it's difficult to follow.
• The reference to "step" (e.g., "step 1" or "step 3") is not clear: does it refer to a line number? A function? A code block? This use is never clarified.

Example 2 (Line 365):
"The wavelength allocation to the ONU - the separate wavelength channel λONUi is assigned to each ONU".
Comment: Variables like λONUi (line 365) and BRONUi (line 368) appear frequently but are not introduced with sufficient context or tied to specific values or calculations.

Therefore, the pseudocode format remains informal, lacking structure, clarity, and connection with standard programming or algorithm notation. It isn't easy to understand or reproduce.

 

c) Methodology transparency/reproducibility

What was requested: Provide clear, justified simulation parameters and modeling assumptions.
Authors' response: indicated that all necessary simulation details were already present in Sections 2, 3.1, and 3.5.
Explaining my comments with evidence: Some descriptive content was added (e.g., parameter lists), but the methodology still lacks justification, modeling rationale, and clarity (for instance, where some parameters are used in the model, with the respective value/range and criteria of choice). Some examples:

Example 1 (Line 205):
"It is supposed that all utilized wavelengths have the same maximum transmission capacity."
Comment: This is a significant modeling assumption, but no value is given or justified by real-world data or literature.

Example 2 (Line 216):
"Examples of the real GPON network traffic loading of Slovak telecom operator are displayed in Figure 2."
Comment: It is not stated whether this data was used in the simulation as input, for validation, or only as a reference. Furthermore, the quality of the figure must be improved for future publication.

Example 3 (Lines 249–277):
Comment: Parameters like N_{ONU}, GC_{ONU}, N_{Ch-OAM}, among others, are defined in a list, but no discussion is provided on their influence, source, or configuration ranges (values). Some values or ranges are provided for specific parameters, but their relations to the methodology and results are not clear. I strongly suggest the author present their parameters with values (or ranges) and criteria of selection/decision. This information must be retaken for the pseudocodes and further discussion, explaining the results based on the choices.

Example 4 (Line 259):
"A number of WDM channels NCh-WDM – under consideration for WDM or OAM/WDM operating technologies; a range of wavelengths can be from 850 nm up to 1625 nm, after inserting the minimum and maximum wavelengths, a number of WDM channels is calculated based on the maximum channel transmission rate and used various channel spacing possible from 0,1 nm up to 1,6 nm. The channel spacing for DWDM applications is based on the standard ITU-T G.694.1 from 12,5 GHz to 100 GHz [18]."
Comment: Which number is considered? How is the channel spacing explicitly calculated? Maybe the pseudocodes could be referred to definitions like this, with information on the used values (ranges).

 

d) Result analysis and discussion

What was requested: Strengthen the analytical depth of the results section; interpret data and connect it to prior work.
Authors' response: You noted enhanced commentary in Sections 4 and 5, with graphical expansion omitted to avoid overlength.
Explaining my comments with evidence: The analysis remains highly descriptive, lacking rigor and critical interpretation.

Example 1 (Line 351):
"With increasing the number of ONU units, the difference between resource efficiencies (…) is also increasing."
Comment: This vague description lacks quantitative evidence and deeper insight (e.g., why does it increase? How much? In what cases?).

Example 2 (line 528):
"In Table 3, output parameters of three allocation methods analyzed in the OAM&WDM-PON network are summarized. It is obvious that a cooperation of both operation technologies brings primarily marked and expressive possible WDM channel savings σCh-WDM."
Comment: Again, why this result? What are the pros and cons of adopting such cooperation? Some behaviors are "obvious" to the Author, but I could not understand the consequences of the results based on the adopted methodology.

Example 3 (Conclusion):
Comment: all your discussions and Figures must come before the conclusions. Unfortunately, no statistical analysis, confidence intervals, benchmarks, or performance comparisons are commented on to support the presented results. Are the results statistically relevant?

 

e) Novelty and literature comparison

What was requested: Demonstrate novelty through meaningful comparisons with related work.
Authors' response: You stated that no directly comparable work exists and that the extensive referencing in the introduction demonstrates the paper's originality.
Explaining my comments with evidence: Although references are listed, no performance, conceptual, or methodological comparisons are made to related studies.

Example (Lines 65–119):
Comment: You cite studies involving OAM-PON systems [7–14] but do not contrast your method's performance or structure with theirs. Even if your exact architecture is novel, comparison with related methods (e.g., Dynamic Bandwidth Allocation, heuristic scheduling) is essential to support claims of originality and significance.

 

In conclusion, the paper still needs substantial improvement before it can be published.

Comments on the Quality of English Language

It has been mentioned previously.

Author Response

Please see attachment

Author Response File: Author Response.pdf