Task-Based Quantizer for CSI Feedback in Multi-User MISO VLC/RF Systems

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript presents a contribution focused on a TQ-CE scheme aimed at addressing the trade-off between channel feedback overhead and channel estimation performance in MISO VLC systems. However, significant revisions are necessary.

• Upon reading the introduction, it becomes clear that it divides into three sections:

Background and Motivation, covering lines 25 to 44

Related Works, covering lines 45 to 76

Main Contribution, covering lines 77 to 91

It would be preferable to explicitly structure these sections under separate headings, particularly by expanding the first part. This reorganization would enhance the clarity and readability of the introduction, making it easier to understand the article’s positioning within the state of the art.

• The authors use several abbreviations such as CSI, MISO, TQ-CE…., among others. It is recommended to include a table of abbreviations to enhance the accessibility and readability of the paper.
• The authors repeatedly highlight that their architecture achieves data rate gains of 0.25 Mbit/s and 0.62 Mbit/s over scalar and vector quantization-based channel estimation schemes, respectively (lines 19 and 91), but no reference is provided to support these claims.
• A comparative study with recent works in the field is necessary to clearly demonstrate the uniqueness of the proposed approach, such as (1109/JIOT.2025.3558497)
• It is recommended that the authors establish a connection between the proposed solution and potential real-world applications that could benefit from it, such as IoT systems or other communication scenarios.
• The authors have not discussed the limitations of their solution, which would be important for a comprehensive assessment of its performance and applicability.
• The authors should include the simulation results in the abstract as well as in the conclusion, with numerical values. An improvement of the conclusion is also recommended to strengthen the clarity of the paper’s contributions.
• The section on future works is missing from this paper.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

 This paper proposes a novel task-based quantizer for uplink MISO visible light communication (VLC) systems. The main idea is interesting, however, followings concerns should be addressed to improve the quality of the paper.

1). According to the reviewer view the CSI transmission through uplink is a low throughput process and require a small capacity. Please justify the sentence "Since the RF bandwidth resources are limited, CSI is quantified to reduce the uplink resource requirements, which however inevitably causes CSI estimation errors at the BS. " with references explanations. May be for particular application?

2). The introduction discuss several MISO techniques used such as spatial modulation, spatial diversity, multiplexing, and propose quantization of CSI as a approach to improve the uplink transmission or improve the accuracy of CSI. However, there are other technique as well such as CSI prediction, and interpolation are used. Better to provide some discussion on such techniques. Some example papers are given below. 

a).  Channel Estimation in Visible Light Communication Systems: The Effect of Input Signal-Dependent Noise

b). Neural Network-Based Channel Estimation and Detection in Spatial Modulation VLC Systems

c). Spline Interpolation Based Channel Estimation for ACO-OFDM over Visible Light Channels

3). Please indicate important system parameters on the Fig. 1. Specially, mathematical notations used in the paper.

4). Results figures, Fig. 4 and Fig. 5 are not smooth. Try to smoothen using increased number of samples when averaging.

5). In Fig. 4 and Fig. 5, at very low SNR (below 5 dB), MSE of SQ-CE is the lowest while, TQ-CE is the highest, this is counter trending to other SNR region. Explain this behavior with justifications.

6). The conclusion of the paper is weak, improve with insightful discussions. Better to provide average gains as well.

7). Use consistent formatting for references. For journals use abbreviations. For conferences use "in Proc. xx".

8). What is the gain of throughput or number of bits when this scheme is used compared to traditional CSI uplink transmission or other benchmark schemes.

Any papers recommended in the report are for reference only. They are not mandatory. You may cite and reference other papers related to this topic.

 

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This paper studies the uplink CSI feedback overhead and channel estimation accuracy issue in a multiuser MISO VLC/RF system. A task-based quantizer (TQ-CE) scheme is introduced. The proposed TQ-CE algorithm aims to ensure the accuracy of channel state information (CSI) estimation at the base station while minimizing RF resource costs. Simulations results demonstrate the advantages of the proposed TQ-CE in terms of data rate compared with the literature.

 

There are some enhancements can be made:

1) The analysis of experimental results is not deep enough. While comparing the proposed scheme with conventional scalar quantization-based and vector quantization-based channel estimation schemes, the paper presents the performance differences without examining the underlying reasons.

2) The paper lacks the analysis of the computational complexity of the proposed TQ-CE algorithm. The absence of a computational complexity comparison between TQ-CE and traditional schemes makes it challenging to fully evaluate the advantages and limitations.

3) The organization and English writing can be further improved to highlight the main contributions. The current content did not highlight the novelty very clearly.

4) The introduction should be polished, since the current version is hard to follow. Some comparison tables with the literature and some conclusive statements should be added.

Comments on the Quality of English Language

See above. 

 

Author Response

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Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

This paper proposes a novel TQ-CE scheme to address the trade-off between channel feedback overhead and channel estimation performance in MISO VLC systems. The superiority of TQ-CE has been demostrated by simulation and numerical results. The paper is well written and organized. The novelty of the proposed algorithm is convinced. If they can demostrate it by experiments, the work can be more meaningful. 

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have responded satisfactorily to the requested revisions. The manuscript has been improved and is now in an appropriate form for publication.

Reviewer 2 Report

Comments and Suggestions for Authors

Authors have well addressed all the comments. No further comments from the reviewer.

Reviewer 3 Report

Comments and Suggestions for Authors

The revision is fine.