X-Git-Url: https://bilbo.iut-bm.univ-fcomte.fr/and/gitweb/ThesisAli.git/blobdiff_plain/df0ded57ac60ab03ead82d37326459a25812634a..025698f711cfa8d174abdf309b09da921696771e:/CHAPITRE_05.tex?ds=inline diff --git a/CHAPITRE_05.tex b/CHAPITRE_05.tex index f1dafcd..8565568 100644 --- a/CHAPITRE_05.tex +++ b/CHAPITRE_05.tex @@ -92,12 +92,12 @@ The difference with MuDiLCO in that the elected leader in each subregion is for each round of the sensing phase. Each sensing phase is itself divided into $T$ rounds and for each round a set of sensors (a cover set) is responsible for the sensing task. %Each sensor node in the subregion will receive an ActiveSleep packet from leader, informing it to stay awake or to go to sleep for each round of the sensing phase. Algorithm~\ref{alg:MuDiLCO}, which will be executed by each node at the beginning of a period, explains how the ActiveSleep packet is obtained. In this way, a multiround optimization process is performed during each -period after Information~Exchange and Leader~Election phases, in order to produce $T$ cover sets that will take the mission of sensing for $T$ rounds. \textcolor{blue}{The flow chart of MuDiLCO protocol that executed in each sensor node is presented in \ref{flow5}.} +period after Information~Exchange and Leader~Election phases, in order to produce $T$ cover sets that will take the mission of sensing for $T$ rounds. \textcolor{blue}{The flowchart of MuDiLCO protocol executed in each sensor node is presented in Figure \ref{flow5}.} \begin{figure}[ht!] \centering \includegraphics[scale=0.50]{Figures/ch5/Algo2.png} % 70mm -\caption{The flow chart of MuDiLCO protocol.} +\caption{The flowchart of MuDiLCO protocol.} \label{flow5} \end{figure} @@ -340,8 +340,8 @@ Obviously, in that case, DESK and GAF have fewer active nodes since they have a %\label{ch5:sec:03:02:03} Figure~\ref{fig6} reports the cumulative percentage of stopped simulations runs per round for 150 deployed nodes. This figure gives the breakpoint for each method. -DESK stops first, after approximately 45~rounds, because it consumes the more energy by turning on a large number of redundant nodes during the sensing phase. GAF stops secondly for the same reason than DESK. MuDiLCO overcomes DESK and GAF because the optimization process distributed on several subregions leads to coverage preservation and so extends the network lifetime. Let us -emphasize that the simulation continues as long as a network in a subregion is still connected. \\ +DESK stops first, after approximately 45~rounds, because it consumes the more energy by turning on a large number of redundant nodes during the sensing phase. GAF stops secondly for the same reason than DESK. \\\\\\ MuDiLCO overcomes DESK and GAF because the optimization process distributed on several subregions leads to coverage preservation and so extends the network lifetime. Let us +emphasize that the simulation continues as long as a network in a subregion is still connected. \begin{figure}[t] @@ -388,7 +388,7 @@ the number of sensors involved in the integer program, the larger the time comp We observe the impact of the network size and of the number of rounds on the computation time. Figure~\ref{fig77} gives the average execution times in -seconds (needed to solve optimization problem) for different values of $T$. The original execution time is computed as described in chapter 4, section \ref{ch4:sec:04:02}. +seconds (needed to solve optimization problem) for different values of $T$. \\\\\\ %The original execution time is computed on a laptop DELL with Intel Core~i3~2370~M (2.4 GHz) processor (2 cores) and the MIPS (Million Instructions Per Second) rate equal to 35330. To be consistent with the use of a sensor node with Atmels AVR ATmega103L microcontroller (6 MHz) and a MIPS rate equal to 6 to run the optimization resolution, this time is multiplied by 2944.2 $\left( \frac{35330}{2} \times \frac{1}{6} \right)$ and reported on Figure~\ref{fig77} for different network sizes. @@ -399,7 +399,7 @@ seconds (needed to solve optimization problem) for different values of $T$. The \label{fig77} \end{figure} -As expected, the execution time increases with the number of rounds $T$ taken into account to schedule the sensing phase. The times obtained for $T=1,3$ or $5$ seem bearable, but for $T=7$ they become quickly unsuitable for a sensor node, especially when the sensor network size increases. Again, we can notice that if we want to schedule the nodes activities for a large number of rounds, +The original execution time is computed as described in chapter 4, section \ref{ch4:sec:04:02}. As expected, the execution time increases with the number of rounds $T$ taken into account to schedule the sensing phase. The times obtained for $T=1,3$ or $5$ seem bearable, but for $T=7$ they become quickly unsuitable for a sensor node, especially when the sensor network size increases. Again, we can notice that if we want to schedule the nodes activities for a large number of rounds, we need to choose a relevant number of subregions in order to avoid a complicated and cumbersome optimization. On the one hand, a large value for $T$ permits to reduce the energy overhead due to the three pre-sensing phases, on the other hand a leader node may waste a considerable amount of energy to solve the optimization problem. %\\ \\ \\ \\ \\ \\ \\ @@ -425,7 +425,7 @@ protocol maximizes the lifetime of the network. In particular, the gain i The slight decrease that can be observed for MuDiLCO-7 in case of $Lifetime_{95}$ with large wireless sensor networks results from the difficulty of the optimization problem to be solved by the integer program. -This point was already noticed in \ref{subsec:EC} devoted to the +\\\\\\\\This point was already noticed in \ref{subsec:EC} devoted to the energy consumption, since network lifetime and energy consumption are directly linked. \end{enumerate}