Uplink and Downlink NOMA Based on a Novel Interference Coefficient Estimation Strategy for Next-Generation Optical Wireless Networks

Round 1

Reviewer 1 Report

1.     Eq. (5) is not clear. What is X? What is signal model?

2.     What is power allocation ratio? Definition is needed

3.     Proposed new modification of SIC algorithm is Eq. (4). BER performance comparison of convention SIC and its new modification is needed. This comparison must demonstrate an advantage of proposed modification of SIC algorithm.

Author Response

Dear Reviewer,

Thank you very much for your valuable time, efforts and remarks. Please find our response letter in the attached document. 

Author Response File: Author Response.pdf

Reviewer 2 Report

The main contribution of this work is:

“A novel successive interference cancellation detection algorithm is proposed to improve the accuracy of interference estimation by introducing interference coefficients in optical NOMA system. Collecting light based on fluorescent concentrator improves the light collection efficiency in uplink optical NOMA.”

This article's English writing, organization, and presentation quality are good. Overall the scientific contribution of this article is high. This work can easily fit into OSA or IEEE venues. I have a few minor suggestions:

1)    Both the Abstract and Conclusions are nicely written and meaningful and focus on key contributions to make them easily understandable for readers.

2)    Introduction provides sufficient reference literature and discussion.

3) Table 1 must be divided into two Tables for the Characteristics and Optical Performances of QDs.

4)    System model and Material properties are fully provided, often discussed in related articles.

5)    The key strength of this work is using two different QDs for experimental demonstration and providing analysis for both Uplink and Downlink. Usually, NOMA articles focus on single links and a single material. The article shows good scientific contributions in this domain.

6)    Experiments and results analysis are comprehensively discussed.

7)     Figures are nicely drawn, and the quality is also fine.

8)    The authors should recheck if all the abbreviations are fully defined.

9)    The authors have reported 40 mbps data rate. How to improve data rate in future works for NOMA?

10)                  It will be interesting if authors can add a Table in the end and compare their work with previously reported works. (Optional)

 

11)                  There is some inconsistency in reference writing. The authors should pay attention to it. 

Scientific language is acceptable.

Author Response

Dear Reviewer,

Thank you very much for your valuable time, efforts and remarks. Please find our response letter in the attached document. 

Author Response File: Author Response.pdf

Reviewer 3 Report

This paper gives a substantial investigation of the uplink and downlink NOMA based on a novel interference coefficient estimation strategy for next-generation optical wireless networks. The considered topic is interesting and useful. Nevertheless, the Reviewer holds some concerns about this work which you can find below. I suggest that the authors revise and improve the manuscript accordingly.

 

The clarity of writing should be improved to explain the key insights and significance of the analytical results. In the introduction, the author should further highlight the significant technical challenge of the analysis compared to previous works and summarize new insights provided by the results of this work.

 

Abstract: “It can also raise potential security concerns, including identity theft, eavesdropping, and session hijacking.” This conclusion is not the thesis of this work. I cannot get this from this work.

 

Introduction: OCDMA, LEDs, CSI, are these abbreviations used again in the following parts? Otherwise, delete them.

 

What is the difference between this work and others (such as 10.1109/LCOMM.2023.3257516)? The Reviewer thinks the comparison is helpful to the readers.

 

Taking into consideration the topic of this paper, authors are strongly advised to extend the number as well as the scope of cited references. Do look for additional journal papers and conference proceedings focused on, i.e., channel fading, RF/FSO, NOMA, etc. The following reference could help the readers and prevent misleading of previously undertaken research works (10.1109/TVT.2023.3252822, 10.1109/TWC.2020.2974947).

 

“One crucial challenge is how to allocate power to NOMA users when there are limited resources.” I do not know why the authors gave this expression. Does this work, try to allocate power to NOMA users?

 

2.2. Uplink NOMA: What is the meaning of FOV? Is there any difference with FoV?

 

“In practice, interference reconstruction is complicated in the SIC detection for multiple users, so they are generally divided into different pairs, and the detection is easily implemented for the two users. The transmitter assigns higher power P1 to the first user’s signal x1, which is far from the transmitter, and assigns lower power P2 to the second user’s signal x2, which is near to the transmitter.” These sentences are incorrect since the interference between the users should not be simplified as a near user and a far user. 

 

Eq. (3): The bandwidth of the system should be taken into account.

 

4.1. The analysis for uplink NOMA-VLC: “As the bias current continues to increase from 0.6A, all BERs increase for all users.” This sentence should be corrected. In addition, there are specific typographical and grammatical errors throughout the manuscript. The authors are suggested to proofread the paper. In addition, the authors are advised to recheck the manuscript once and remove those errors.

Minor editing of English language required.

Author Response

Dear Reviewer,

Thank you very much for your valuable time, efforts and remarks. Please find our response letter in the attached document. 

Author Response File: Author Response.pdf

Reviewer 4 Report

Authors presents the BER performance of the proposed LSM-SIC algorithm for NOMA system.

The overall description and quality of the paper is quite well to be accepted for publishing, only if some minor correction are revised.

1. Need to add comment on multiple user's scenario in Section of Result or Conclusion.

2. From Fig. 10 ~ to Fig. 18, all the lines should be clearly distinguished from others, with selecting the line and symbol style and legend.

The quality of English used in this paper is quite well written. I suggest authors should check the typos and grammar throughout the whole of paper.

Author Response

Dear Reviewer,

Thank you very much for your valuable time, efforts and remarks. Please find our response letter in the attached document. 

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

This manuscript can be accepted this time since all my concerns have been well solved.