An Efficient Wireless Sensor Network Based on the ESP-MESH Protocol for Indoor and Outdoor Air Quality Monitoring
, Mohammad Ehtisham Khan 2, Mashhood Hasan 1, Waleed Zakri 3, Waleed Alhazmi 3 and Tarikul Islam 4
Round 1
Reviewer 1 Report
In conclusion that the ESP-MESH network protocol offers a considerably good quality of service mainly for medium-area networks, please specify why is the QoS "considerably good" by some references--
Author Response
We are very thankful to the reviewers for their valuable comments and support to improve the quality of the paper.
We have revised the manuscript along the lines suggested by the reviewers. Detailed answers to the questions by the Reviewers and descriptions of how we took into account the reviewers’ comments in preparing the revised manuscript are given below.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Certainly, the manuscript is well and clearly written. Unfortunately, I have not found the scientific contribution inside.
It consists of two parts. First, it describes how to select and connect standard devices using standard ic-ic interfaces. It is done perfectly well, but the difficulty is low – similar work is typically undertaken by students as an interim project. The second part is the engagement of the off-the-shelf library in the project. Again, it is selected correctly, but embedding publicly available libraries in an own project is a standard competence of a computer science engineer.
If the contribution involves evaluation of the library, then there is not enough information concerning noise, interferences, background load patterns, and similar, to assess the result. The manuscript does not include hints on how to establish sinks, backup sinks (if fair comparison to mentioned LoRa is desired), how to synchronize nodes (necessary, if mentioned TDMA is used), how to recover after node fault, and so on.
Minor suggestions:
74-75: As far as I know, currently BTLE is willingly used, as well.
What is the difference between Fig. 13 and Fig. 16a? The same caption, but slightly different data.
To be honest, I do not know, why the environment was monitored for 72 minutes, but the system works for 5 days (i.e., 7200 minutes). Which task did it perform 99% of the time?
Author Response
We are very thankful to the reviewers for their valuable comments and support to improve the quality of the paper.
We have revised the manuscript along the lines suggested by the reviewers. Detailed answers to the questions by the Reviewers and descriptions of how we took into account the reviewers’ comments in preparing the revised manuscript are attached.
Author Response File: Author Response.pdf
Reviewer 3 Report
The article presented here is about - basically, it is not clear what, and certainly not clear what scientific problem. Of course - the problem of air pollution is very important, but it seems that this was not supposed to be the main subject of the article. It seems that the authors wanted to present ESP MESH technology about its potential application. I think this is too little for a scientific article in a serious journal.
I think the content of the article is interesting and important, but it should be encased in a scientific setting. Otherwise, it is suitable for publication on a personal website, for example.
I suggest you definitely expand the mathematical apparatus, describe the measurement methods in detail, develop the data statistically, etc.
Regards!
Author Response
We are very thankful to the reviewers for their valuable comments and support to improve the quality of the paper.
We have revised the manuscript along the lines suggested by the reviewers. Detailed answers to the questions by the Reviewers and descriptions of how we took into account the reviewers’ comments in preparing the revised manuscript are attached.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
My opinion concerns the evaluation of the protocol, only. The remaining parts are good engineering work without scientific contribution. In general, I have found the work after the review process much better than previously.
Below I point out the issues which are my opinion described too briefly:
1. The selection of sink(s) based on RSSI is “fragile” because RSSI fluctuates much. The authors bypass the problem by setting node A net to the router. The foregoing of voting is risky in a dynamic environment and typically (but not here) is recurred or monitored (e.g., root switch selection). In my opinion discussion concerning the stability of these processes is desired.
2. The delivery ratio decreases with the distance to the sink. However, if TDMA works correctly, such behavior should not be observed. The system is certainly NOT overloaded. What is the reason? Fig. 17 presents fluctuation of the transmission reliability, but without explanation.
Author Response
We are very thankful to the reviewer for their valuable comments and support to improve the quality of the paper.
We have revised the manuscript along the lines suggested by the reviewers. Detailed answers to the questions by the Reviewers and descriptions of how we took into account the reviewers’ comments in preparing the revised manuscript are given below.
Author Response File: Author Response.pdf
Reviewer 3 Report
Dear Authors,
thank you for revising the article and making corrections. At the moment, it seems that the article has gained some scientific value, which was most lacking in its first version. I believe it is suitable for publication in the journal Sustainability.
I wish you good luck in your further scientific work.
Author Response
We are very thankful to the reviewer for their valuable comments and support to improve the quality of the paper.
