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11 %\titleformat*{\section}{\Large\bfseries}
13 %\title{Response to the reviewers of \bf "Perimeter-based Coverage Optimization to Improve Lifetime in Wireless Sensor Networks"}
14 %\author{Ali Kadhum Idrees, Karine Deschinkela, Michel Salomon and Raphael Couturier}
22 \vspace{-0.5cm}\hspace{-2cm}FEMTO-ST Institute, UMR 6174 CNRS
24 \hspace{-2cm}University Bourgogne Franche-Comt\'e
26 \hspace{-2cm}IUT Belfort-Montb\'eliard, BP 527, 90016 Belfort Cedex, France.
31 Detailed changes and addressed issues in the revision of the article
33 ``Perimeter-based Coverage Optimization \\
34 to Improve Lifetime in Wireless Sensor Networks''\\
36 by Ali Kadhum Idrees, Karine Deschinkel, Michel Salomon and Raph\"ael Couturier
41 Dear Editor and Reviewers,
44 Comments (here in red color) raised by the reviewer n°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.
46 %Journal: Engineering Optimization
47 %Reviewer's Comment to the Author Manuscript id GENO-2015-0094
48 %Title: \bf "Perimeter-based Coverage Optimization to Improve Lifetime in Wireless Sensor Networks"
49 %Authors: Ali Kadhum Idrees, Karine Deschinkela, Michel Salomon and Raphael Couturier
51 \section*{Response to Reviewer No. 1 Comments}
58 \noindent {\bf 3.} The communication and information sharing required to
59 cooperate and make these decisions was not discussed.\\
61 \textcolor{blue}{\textbf{\textsc{Answer:} The communication and information
62 sharing required to cooperate and make these decisions is discussed at the
63 end of page 8. Position coordinates, remaining energy, sensor node ID, and
64 number of one-hop neighbors are exchanged.}}\\
66 \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.}}\\
68 \textcolor{green}{\textbf{\textsc{Answer:} Right, we have included more description about the INFO packet and the ActiveSleep packet into the write up at the end of page 8}}\\
70 \noindent {\bf 7.} The methodology is implemented in OMNeT++ (network simulator)
71 and tested against 2 existing algorithms and a previously developed method by
72 the authors. The simulation results are thorough and show that the proposed
73 method improves the coverage and network lifetime compared with the 3 existing
74 methods. The results are similar to previous work done by their team.\\
76 \textcolor{blue}{\textbf{\textsc{Answer:} Although the study conducted in this
77 paper reuses the same protocol presented in our previous work, we focus in
78 this paper on the mathematical optimization model developed to schedule
79 nodes activities. We deliberately chose to keep the same performance
80 indicators to compare the results obtained with this new formulation with
81 other existing algorithms.}}\\
83 \textcolor{red}{\textbf{\textsc{Reviewer's response:}
84 I agree that you should show the same performance indicators and that this paper is
85 about the way you formulated the problem. The mathematical optimization model is the main
86 contribution but it's less convincing since the results are slightly better if not the same for the two
87 methodologies you have developed. Could you include some other measure that shows that the
88 PeCO is better? Maybe include computation time or something that is as convincing as the energy
89 consumed per sensor.}}
91 \textcolor{green}{\textbf{\textsc{Answer:} In fact, we included a new performance metric that linked to the energy, called Energy Saving Ratio (ESR). We added new section in the result part related to this performance metric that shows our PeCO protocol provides better energy saving compared with other approaches.}}\\
95 \noindent {\bf 8.} Since this paper is attacking the coverage problem, I would
96 like to see more information on the amount of coverage the algorithm is
97 achieving. It seems that there is a tradeoff in this algorithm that allows the
98 network to increase its lifetime but does not improve the coverage ratio. This
99 may be an issue if this approach is used in an application that requires high
102 \textcolor{blue}{\textbf{\textsc{Answer:} Your remark is very interesting. Indeed,
103 Figures 8(a) and (b) highlight this result. The PeCO protocol allows to achieve
104 a coverage ratio greater than $50\%$ for far more periods than the others
105 three methods, but for applications requiring a high level of coverage
106 (greater than $95\%$), the DiLCO method is more efficient. It is explained at
107 the end of Section 5.2.4.}}\\
109 \textcolor{red}{\textbf{\textsc{Reviewer's response:}
110 I'm glad you added the explanation. I am confused with your conclusion in the last
111 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
112 you would want to have a coverage ratio of $50\%$? This seems like a very small ratio and as you
113 increase it, DiLCO becomes the methodology that has the maximum network lifetime. If you don't
114 include application examples, your statement "Indeed there are applications that do not require a
115 100$\%$ coverage of the area to be monitored." stronger. }}
117 \textcolor{green}{\textbf{\textsc{Answer:} Thank you so much to your suggestion for adjusting the sentence in the end of Section 5.2.5. (previously Section 5.2.4.), It is done.
118 For the applications, we added some applications examples in the end of the sentence "Indeed there are applications that do not require a 100$\%$ coverage of the area to be monitored." as well as we changed the figure 10 (previously figure 9) by adding DilCO/70 and PecO/70 instead of DilCO/50 and PeCO/50 }}\\