concluding remarks and some suggestions for future works in
Section~\ref{sec:conclusion}.
+
+%%RC : Related works good for a phd thesis but too long for a paper. Ali you need to learn to .... summarize :-)
\section{Related works} % Trop proche de l'etat de l'art de l'article de Zorbas ?
\label{rw}
%The sensor node enter in listening mode waiting to receive ActiveSleep packet from the leader after the decision to apply multi-round activity scheduling during the sensing phase. Each sensor node will execute the Algorithm~1 to know who is the leader. After that, if the sensor node is leader, It will execute the integer program algorithm ( see section~\ref{cp}) to optimize the coverage and the lifetime in it's subregion. After the decision, the optimization approach will produce the cover sets of sensor nodes to take the mission of coverage during the sensing phase for $T$ rounds. The leader will send ActiveSleep packet to each sensor node in the subregion to inform him to it's schedule for $T$ rounds during the period of sensing, either Active or sleep until the starting of next period. Based on the decision, the leader as other nodes in subregion, either go to be active or go to be sleep based on it's schedule for $T$ rounds during current sensing phase. the other nodes in the same subregion will stay in listening mode waiting the ActiveSleep packet from the leader. After finishing the time period for sensing, which are includes $T$ rounds, all the sensor nodes in the same subregion will start new period by executing the MuDiLCO protocol and the lifetime in the subregion will continue until all the sensor nodes are died or the network becomes disconnected in the subregion.
\subsection{Background idea}
-
+%%RC : we need to clarify the difference between round and period. Currently it seems to be the same (for me at least).
The area of interest can be divided using the divide-and-conquer strategy into
smaller areas, called subregions, and then our MuDiLCO protocol will be
implemented in each subregion in a distributed way.
%For each round a set of sensors (said a cover set) is responsible for the sensing task.
This protocol is reliable against an unexpected node failure, because it works
-in periods. On the one hand, if a node failure is detected before making the
+in periods.
+%%RC : why? I am not convinced
+ On the one hand, if a node failure is detected before making the
decision, the node will not participate to this phase, and, on the other hand,
if the node failure occurs after the decision, the sensing task of the network
will be temporarily affected: only during the period of sensing until a new
period starts.
+%%RC so if there are at least one failure per period, the coverage is bad...
The energy consumption and some other constraints can easily be taken into
account, since the sensors can update and then exchange their information
We define two types of packets that will be used by the proposed protocol:
\begin{enumerate}[(a)]
-\item INFO packet: a such packet will be sent by each sensor node to all the
+\item INFO packet: such a packet will be sent by each sensor node to all the
nodes inside a subregion for information exchange.
\item Active-Sleep packet: sent by the leader to all the nodes inside a
subregion to inform them to remain Active or to go Sleep during the sensing
belongs. The integer program will produce $T$ cover sets, one for each round.
The WSNL will send an Active-Sleep packet to each sensor in the subregion based
on the algorithm's results, indicating if the sensor should be active or not in
-each round of the sensing phase. The integer program is based on the model
-proposed by \cite{pedraza2006} with some modification, where the objective is to
-find a maximum number of disjoint cover sets. To fulfill this goal, the authors
-proposed an integer program which forces undercoverage and overcoverage of
-targets to become minimal at the same time. They use binary variables $x_{jl}$
-to indicate if sensor $j$ belongs to cover set $l$. In our model, we consider
-binary variables $X_{t,j}$ to determine the possibility of activation of sensor
-$j$ during the round $t$ of a given sensing phase. We also consider primary
-points as targets. The set of primary points is denoted by $P$ and the set of
-sensors by $J$. Only sensors able to be alive during at least one round are
-involved in the integer program.
+each round of the sensing phase. The integer program is based on the model
+proposed by \cite{pedraza2006} with some modifications, where the objective is
+to find a maximum number of disjoint cover sets. To fulfill this goal, the
+authors proposed an integer program which forces undercoverage and overcoverage
+of targets to become minimal at the same time. They use binary variables
+$x_{jl}$ to indicate if sensor $j$ belongs to cover set $l$. In our model, we
+consider binary variables $X_{t,j}$ to determine the possibility of activation
+of sensor $j$ during the round $t$ of a given sensing phase. We also consider
+primary points as targets. The set of primary points is denoted by $P$ and the
+set of sensors by $J$. Only sensors able to be alive during at least one round
+are involved in the integer program.
%parler de la limite en energie Et pour un round
%(W_{\theta}+W_{\psi} = P) \label{eq19}
%\end{equation}
+%%RC why W_{\theta} is not defined (only one sentence)? How to define in practice Wtheta and Wu?
+
+
\begin{itemize}
\item $X_{t,j}$: indicates whether or not the sensor $j$ is actively sensing
during the round $t$ (1 if yes and 0 if not);
that the deployed nodes can cover the sensing field with the given sensing
range.
+%%RC these parameters are realistic?
+%% maybe we can increase the field and sensing range. 5mfor Rs it seems very small... what do the other good papers consider ?
+
\begin{table}[ht]
\caption{Relevant parameters for network initializing.}
% title of Table
% is used to refer this table in the text
\end{table}
-For sake of simplicity we ignore the energy needed to turn on the radio, to
+For the sake of simplicity we ignore the energy needed to turn on the radio, to
start up the sensor node, to move from one status to another, etc.
%We also do not consider the need of collecting sensing data. PAS COMPRIS
-Thus, when a sensor becomes active (i.e., it already decides it's status), it
-can turn its radio off to save battery. MuDiLCO uses two types of packets for
+Thus, when a sensor becomes active (i.e., it already decides its status), it can
+turn its radio off to save battery. MuDiLCO uses two types of packets for
communication. The size of the INFO packet and Active-Sleep packet are 112~bits
and 24~bits respectively. The value of energy spent to send a 1-bit-content
message is obtained by using the equation in ~\cite{raghunathan2002energy} to
% Therefore, for our simulations, the error in the coverage calculation is less than ~ 1 $\% $.
\item{{\bf Number of Active Sensors Ratio (ASR)}:} it is important to have as
- few active nodes as possible in each round,in order to minimize the
+ few active nodes as possible in each round, in order to minimize the
communication overhead and maximize the network lifetime. The Active Sensors
Ratio is defined as follows:
\begin{equation*}
\end{enumerate}
-%%%%%%%%%%%%%%%%%%%%%%%%VU JUSQU ICI**************************************************
\section{Results and analysis}
Figure~\ref{fig3} shows the average coverage ratio for 150 deployed nodes. We
can notice that for the first thirty rounds both DESK and GAF provide a coverage
-which is a little bit better than the one of MuDiLCO-T. This is due to the fact
-that in comparison with MuDiLCO that uses optimization to put in SLEEP status
+which is a little bit better than the one of MuDiLCO-T.
+%%RC : need to uniformize MuDiLCO or MuDiLCO-T?
+
+%%RC maybe increase the size of the figure for the reviewers, no?
+
+This is due to the fact
+that in comparison with MuDiLCO-T that uses optimization to put in SLEEP status
redundant sensors, more sensor nodes remain active with DESK and GAF. As a
consequence, when the number of rounds increases, a larger number of node
failures can be observed in DESK and GAF, resulting in a faster decrease of the
consumed during the different status of the sensor node. Among the different
versions of our protocol, the MuDiLCO-7 one consumes more energy than the other
versions. This is easy to understand since the bigger the number of rounds and
-the number of sensors involved in the integer program, the larger the time
-computation to solve the optimization problem. To improve the performances of
+the number of sensors involved in the integer program are, the larger the time
+computation to solve the optimization problem is. To improve the performances of
MuDiLCO-7, we should increase the number of subregions in order to have less
sensors to consider in the integer program.
University of Babylon - Iraq for the financial support, Campus France (The
French national agency for the promotion of higher education, international
student services, and international mobility), and the University of
-Franche-Comt\'e - France for all the support in France.
+Franche-Comt\'e - France for all the support in France. This work is partially funded by the Labex ACTION program (contract ANR-11-LABX-01-01).
+
+
%% \linenumbers
