Combined Fusion Rules in Cognitive Radio Networks Using Different Threshold Strategies

Round 1

Reviewer 1 Report

The paper is very well written. The idea of proposing a new adaptive combination algorithm to balance between detection performance of a CRN and its reporting overhead through combining different fusion rules over the CRN,  is nice.

Generally, I like papers that combine existing techniques into a new concept. 

The paper is technically correct. The assumptions done are also reasonable.

My only concern is regarding the results. Generally, I believe that when testing and evaluating network algorithms more reliable simulators should be used (like NS-3) rather than Matlab, if it is of course impossible to employ real testbeds.

In this case, I would like to see a comparison of this algorithm with similar works. Comparing just between the three versions of the same value is of limited value. It is generally pretty obvious that adaptive algorithms outperform fixed threshold strategies. 

I suggest to find an established algorithm on the field and compare your results under the same conditions.  This, will increase the value of your work.  

Author Response

Please see the attached 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments for Authors
October 25, 2019
“Combined Fusion Rules in Cognitive Radio Networks Using Different Threshold Strategies”
General: Authors provide a comparative study among four cluster based CR algorithms that enhances the probability of detection and reducing the false alarm for idle channels in the available spectrum. The general study is acceptable. However, I encourage the authors to address the following comments, which need to be addressed prior to publications of the manuscript:
 Comments:
1. While the introductory section is acceptable, there is a need to enrich the motivation behind the cluster-based approach for CRN and to prompt the advantages of using this approach.
2. The manuscript needs to be enriched with relevant references and focusing on the proposed approach.
3. The simulation study backs up the conclusions. However, No mathematical model is provided to determine the superiority of a certain algorithm over others.
4. Authors are advised to provide a table or text that highlights the distinct contribution of this work compared the authors’ prior work.
 Presentation:
1. Minor language modifications might be needed needed.

Author Response

Please see the attached pdf file.

Author Response File: Author Response.pdf

Reviewer 3 Report

The reviewer request to clearly indicate in the Introduction section the following: motivation of this work, methodology description, and originality of this work. Moreover, the qualitative parameters for evaluating the performances of the proposed scheme must be indicated. More details related the obtained results in the Introduction section are also requested. Resolution of Figure 3 is not appropriate. It is very hard to follow the explanations for Figures 6, 7, 8 and 9. The text is presented and afterwords all the figures are inserted. Please provide result analysis for each figure apart.   The SNR range was selected between [-4,6] dB. Why is this interval representative. Please correlate with a transmission technology / standard. The major drawback in this paper #1: The paper missed some comparison with other centralized CSS schemes using hard decision. A comparative analysis is required. The major drawback in this paper #2: The authors must indicates the benefits of such implementation at the system level (i.e. to integrate this algorithms in a network simulator and to evaluate the impact on QoS and QoE parameters).  Also, not clear which is the impact on energy consumption on each device using these centralized CSS algorithms.

Author Response

Please see the attached file.

Author Response File: Author Response.pdf

Reviewer 4 Report

Overall the paper presents a relevant (though a bit incremental) contribution to the topic.

The proposed contributions are clearly identified, formulated and are supported by a sufficient number of simulation results.

Some comments/suggestions:

Abstract: add a few key quantitative results to illustrate "outperforms".

Section 2.1: add a least one reference to support the provided description.

Section 2.2.1 and Section 2.2.2: since these are within the background section, I expected to see some references also at the beginning of these subsections (in addition to those included in the later parts). 

Figure 3: in my opinion, the figure would be more illustrative if it included some signals between the clusters, FC, and PU, as well as within (some of) the clusters. Consider how you could add such details, but at the same time do not overload the figure. Moreover, the caption could be longer, i.e. it should give more details about what to look for in the figure, not just a high-level title.

Section 3: would it be possible to add a table with key parameters and their values? Make sure these would be coherent with the values used in the experimental part.

Algorithms 1, 2, and 3: use indentation instead of left-aligning everything.

Algorithms 1, 2, and 3: how do their execution times compare with each other? Is is something you can measure in Matlab?

Section 6: ... values of the two-bit softened hard scheme (i.e., β1 and β2) are determined off line using exhaustive search and are stored in a look up table to reduce the computational complexity: can you elaborate on how these could be obtained online and what the computational complexity might be?

Figure 4 to Figure 9: use the color/type of line markers as consistent as possible. This issue is very visible in Figure 8 and Figure 9, where the color/type of line markers are inverted for "Two-bit softened hard" and "One-bit hard". 

Conclusion: as for the abstract, add a few key quantitative results to illustrate "effectiveness" and "significantly reduces".

There some grammatical errors and typos along the text, please check carefully.

Author Response

Dear Assistant editor,

Here is a copy of a cover letter, a revised manuscript, and a response to the reviewers attached as one file altogether.

 

Regards

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The replies provided by the authors regarding the results are not sufficient. As I noted in my first review MATLAB it is not acceptable as a network simulator, while a comparison with an established algorithm in this area is a must in order to prove your contributions.

As I have already mentioned in my previous review,  the topic and the paper are interesting but the evaluation sections need to be reconsidered. 

I don't feel that "time limitations available to respond to reviewers’ comments" is an excuse. Maybe you can ask for an extension from the editor. 

Author Response

Please find the attached file.

Author Response File: Author Response.docx

Reviewer 3 Report

The authors addressed the reviewer's comments. However, two of the major concerns of the reviewer ware considered as not being part of this work. The third major concern was addressed. The reviewer considers and accepts author's arguments.

Author Response

Thanks so much for accepting our response, it is greatly appreciated.