\end{center}
Dear Editor and Reviewers,
-First of all, we would like to thank you very much for your kind help to improve
-our article named: ``Perimeter-based Coverage Optimization to Improve Lifetime
-in Wireless Sensor Networks''. We highly appreciate the detailed valuable
-comments of the reviewers on our article. The suggestions are quite helpful for
-us and we incorporate them in the revised article. We are happy to submit to you
-a revised version that considers most of your remarks and suggestions to improve
-the quality of our article.
-
-As below, we would like to clarify some of the points raised by the reviewers
-and we hope the reviewers and the editors will be satisfied by our responses to
-the comments and the revision for the original manuscript.
+
+Comments (here in red color) raised by the reviewer n\textsuperscript{o}1 after a first revision have been carefully considered. Please find below our answers highlighted in green. We did our best to satisfy your requests.
%Journal: Engineering Optimization
%Reviewer's Comment to the Author Manuscript id GENO-2015-0094
\section*{Response to Reviewer No. 1 Comments}
-This paper proposes a scheduling technique for WSN to maximize coverage and
-network lifetime. The novelty of this paper is the integration of an existing
-perimeter coverage measure with an existing integer linear programming
-model. Here are few comments:\\
-\noindent {\bf 3.} The communication and information sharing required to
+
+\noindent {\textbf{3. \textsc{Reviewer's comment:} } } The communication and information sharing required to
cooperate and make these decisions was not discussed.\\
\textcolor{blue}{\textbf{\textsc{Answer:} The communication and information
\textcolor{red}{\textbf{\textsc{Reviewer's response:} I see at the end of page 8 the description of the INFO packet. However, you are not including any description of the position coordinates, remaining energy, sensor node ID, etc. in the write up. I suggest adding this into the write up to make the communication clear.}}\\
+\textcolor{green}{\textbf{\textsc{Answer:} Right, we have included more description about the INFO packet and the ActiveSleep packet at the end of section~3.}}\\
-\noindent {\bf 6.} The authors have performed a thorough review of existing
-coverage methodologies. However, the clarity in the literature review is a
-little off. Some of the descriptions of the method s used are very vague and do
-not bring out their key contributions. Some references are not consistent and I
-suggest using the journals template to adjust them for overall consistency.\\
-
-\textcolor{red}{\textbf{\textsc{Reviewer's response:} I do like the way you have presented the different literature related to each aspect of
-the problem. I think I was just concerned that the sentences presenting each work are not very
-clear. After reading through them however, everything is clear. I like the addition of the last
-paragraph and believe it is definitely needed since you are directly comparing these
-methodologies.}}
-
-
-\textcolor{blue}{\textbf{\textsc{Answer:} References have been carefully checked
- and seem to be consistent with the journal template. In Section~2, ``Related
- literature'', we refer to papers dealing with coverage and lifetime in
- WSN. Each paragraph of this section discusses the literature related to a
- particular aspect of the problem : 1. types of coverage, 2. types of scheme,
- 3. centralized versus distributed protocols, 4. optimization method. At the
- end of each paragraph we position our approach. We have also added a last
- paragraph about our previous work on DiLCO protocol to explain the
- difference with PeCO. }}\\
-
-\noindent {\bf 7.} The methodology is implemented in OMNeT++ (network simulator)
+\noindent {\textbf{7. \textsc{Reviewer's comment:}}} The methodology is implemented in OMNeT++ (network simulator)
and tested against 2 existing algorithms and a previously developed method by
the authors. The simulation results are thorough and show that the proposed
method improves the coverage and network lifetime compared with the 3 existing
methods. The results are similar to previous work done by their team.\\
-\textcolor{red}{\textbf{\textsc{Reviewer's response:}
-I agree that you should show the same performance indicators and that this paper is
-about the way you formulated the problem. The mathematical optimization model is the main
-contribution but it’s less convincing since the results are slightly better if not the same for the two
-methodologies you have developed. Could you include some other measure that shows that the
-PeCO is better? Maybe include computation time or something that is as convincing as the energy
-consumed per sensor.}}
-
\textcolor{blue}{\textbf{\textsc{Answer:} Although the study conducted in this
paper reuses the same protocol presented in our previous work, we focus in
this paper on the mathematical optimization model developed to schedule
indicators to compare the results obtained with this new formulation with
other existing algorithms.}}\\
-\noindent {\bf 8.} Since this paper is attacking the coverage problem, I would
+\textcolor{red}{\textbf{\textsc{Reviewer's response:}
+I agree that you should show the same performance indicators and that this paper is
+about the way you formulated the problem. The mathematical optimization model is the main
+contribution but it's less convincing since the results are slightly better if not the same for the two
+methodologies you have developed. Could you include some other measure that shows that the
+PeCO is better? Maybe include computation time or something that is as convincing as the energy
+consumed per sensor.}}\\
+
+\textcolor{green}{\textbf{\textsc{Answer:} In fact, we defined in section 5.1 a new performance metric linked to the energy, called Energy Saving Ratio (ESR). We added a new section (5.2.3) in the result part related to this performance metric which shows that our PeCO protocol provides better energy saving compared with other approaches.}}\\
+
+
+
+\noindent {8. \textbf{\textsc{Reviewer's comment:}}} Since this paper is attacking the coverage problem, I would
like to see more information on the amount of coverage the algorithm is
achieving. It seems that there is a tradeoff in this algorithm that allows the
network to increase its lifetime but does not improve the coverage ratio. This
the end of Section 5.2.4.}}\\
\textcolor{red}{\textbf{\textsc{Reviewer's response:}
-I’m glad you added the explanation. I am confused with your conclusion in the last
-sentence though, “DiLCO is better for coverage ratios near 100%, but in that case PeCO is not
-ineffective for the smallest network sizes”. I suggest adjusting it to something like this. “DiLCO
-outperforms PeCO when the coverage ratio is required to be >90%, but PeCo extends the network
-lifetime significantly when coverage ratio can be relaxed. “ Also, can you add applications where
-you would want to have a coverage ratio of 50%? This seems like a very small ratio and as you
-increase it, DiLCO becomes the methodology that has the maximum network lifetime. If you don’t
-include application examples, your statement “Indeed there are applications that do not require a
-100$\%$ coverage of the area to be monitored.” stronger. }}
+I'm glad you added the explanation. I am confused with your conclusion in the last
+sentence though, "DiLCO is better for coverage ratios near $100\%$, but in that case PeCO is not ineffective for the smallest network sizes". I suggest adjusting it to something like this. "DiLCO outperforms PeCO when the coverage ratio is required to be $>90\%$, but PeCo extends the network lifetime significantly when coverage ratio can be relaxed." Also, can you add applications where
+you would want to have a coverage ratio of $50\%$? This seems like a very small ratio and as you
+increase it, DiLCO becomes the methodology that has the maximum network lifetime. If you don't
+include application examples, your statement "Indeed there are applications that do not require a
+100$\%$ coverage of the area to be monitored." stronger. }}\\
+\textcolor{green}{\textbf{\textsc{Answer:} Thank you so much for your suggestion, we modified the sentence at the end of Section 5.2.5. (previously Section 5.2.4.). As recommended, we added some applications examples. We also changed the figure 10 (previously figure 9) by replacing DilCO/50 and PecO/50 by DilCO/70 and PeCO/70.}}\\
-We are very grateful to the reviewers who, by their recommendations, allowed us
-to improve the quality of our article.
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Best regards\\
