Experimental Investigation into the Influence of LED Bias Setup on VLC Frequency Domain Characteristics: Beyond Non-Negativity

Round 1

Reviewer 1 Report

This paper experimentally investigates the influence of the bias voltage on the amplitude-frequency response of the LED, constructs a log-domain linear model, and concludes that the bias setup can remarkably influence the system bandwidth and thus should be taken into consideration for visible light communication system design beyond satisfying nonnegativity requirement. There are, however, some critical points requiring more clarification or correction:

·    It is unclear how to get the fitting lines in the Figures 8 and 9. Are they drawn according to the deduced Eq. (9)? If Yes, it can be shown that the deduced equations is general, and authors should give the corresponding explanation in the text. If Not, it is strongly suggested to verify the proposed model suitable to predict the amplitude-frequency response at any bias voltage.

·    What determines such relationship between the amplitude-frequency response and the bias voltage as described in this manuscript?

·    Why not include the influence of the bias voltage on the amplitude-frequency response of the LED?  How about the difference with and without considering this influence? Is it necessary to consider this influence at any situation?

·    In the line 73, how to understand ‘…. LED x(t) + U_bias is bipolar, x(t) + U_bias ≥ 0.’? It seems inconsistent.

·    The English expressions and the grammar need a careful and thorough check. Here are some examples below:

×      Paper or letter? Please choose one in the whole manuscript.

×      In the line 15, ‘…. diode (LED) as transmitters ….’ -> …. diodes (LEDs) as transmitters ….

×      The connection word ‘and’ should be used between the last two expressions or sentences. For example, in the line 17, after the word ‘instance’, ‘and’ should be added.

×       In the line 42, who is the subject of the ‘decrease’? please check and use the right form of this word.

….

I strongly recommend the authors address these critical points to make the manuscript qualified to the journal.

The English expressions and the grammar need a careful and thorough check. Here are some examples below:

×   Paper or letter? Please choose one in the whole manuscript.

×   In the line 15, ‘…. diode (LED) as transmitters ….’ -> …. diodes (LEDs) as transmitters ….

× The connection word ‘and’ should be used between the last two expressions or sentences. For example, in the line 17, after the word ‘instance’, ‘and’ should be added.

×     In the line 42, who is the subject of the ‘decrease’? please check and use the right form of this word.

….

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

This article leverages relationship between BC and LED characteristics, explore its impact on VLC. Revealed that the equivalent spectral function H(f) can be well approximated by a log-domain function with respect f. Before the manuscript is published, the author needs to response the following reviews:

 

1.Relevant research background needs to be supplemented in INTRODUCTION. The background of the problem research is not clear enough to highlight the significance of its work.

2.The overall format of the paper should be standardized. Introduction as the first part of the paper, why not use 1 as a label?

3.Another obvious problem with this paper is lack of sufficient explanation of the simulation results. You need to explain your simulation results in detail and why you got such results.The significance of this paper is not expound sufficiently. The author need to highlight this paper's innovative contributions.

4.The pictures in the text are all in black and white format, because there are multiple parameters in the picture, it is recommended to label different colors for comparison. The pictures in your paper are a bit blurry. Please consider replacing them with clearer ones.

5.The research content only selects the known conclusions and analyzes the relationship and impact therein, but does not give very in-depth conclusions.

I think the readers can understand the manuscript. But the quality of English language can be improved.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors have answered all the questions and modified the manuscript according to the comments. I suggest that this manuscript can be accepted for publication in Photonics.