- Performance evaluation and optimization solvers are important tools and they are received a great interest by many researchers around the world. In the last few years, several intensive researches have been done about the WSNs, and for a large range of real world applications. Therefore, the performance evaluation of algorithms and protocols becomes challenging at various stages of design, development and implementation. In order to perform an efficient deployment, it is desirable to analyze the performance of the newly designed algorithms and protocols in WSNs. Performance evaluation tools are became precious means for evaluating the efficiency of algorithms and protocols in WSNs.
-On the other side, the main challenges in the design of WSNs have given rise to a new hard and complex theoretical problems in optimization area. These optimization problems are related to several topics in WSNs such as coverage, topology control, scheduling, routing, mobility, etc. So, the optimization is very important in WSNs because the limited resources of the sensor nodes. For this reason, several proposed optimization problems are mathematically formulated so as to optimize the network lifetime and satisfy the application requirements. Therefore, in order to get the optimal solutions for these mathematical optimization problems, the optimization solver is the best candidate tool to solve them. The optimization solver takes mathematical optimization problem descriptions in a certain file format and calculate their optimal solution.
+Performance evaluation and optimization solvers are important tools. In the last few years, several intensive researches have been done about the WSNs, and for a wide range of real-world applications. Therefore, the performance evaluation of algorithms and protocols becomes challenging at various stages of design, development, and implementation. In fact, to perform an efficient deployment, it is desirable to analyze the performance of the newly designed algorithms and protocols in WSNs. Since performance evaluation tools are becoming precious means for evaluating the efficiency of algorithms and protocols in WSNs, they have received a great interest by many researchers around the world.
+On the other side, the main challenges in the design of WSNs handle new hard and complex theoretical optimization problems. These optimization problems are related to several topics in WSNs such as coverage, topology control, scheduling, routing, mobility, etc.
+%So, the optimization is very important in WSNs because the limited resources of the sensor nodes.
+For this reason, several problems are modeled by an optimization problem for instance to optimize the network lifetime while satisfying the application requirements.
+%Therefore, in order to get the optimal solutions for these mathematical optimization problems, the optimization solver is the best candidate tool to solve them. The optimization solver takes mathematical optimization problem descriptions in a certain file format and calculates their optimal solution.
+Optimization solvers dedicated to specific resolution methods (meta-heuristics, linear programming, etc) are required.
+%Many important real-world problems have formulated as integer programming problems.
+In this dissertation, we use linear programming because we used integer programs to optimize the coverage and the lifetime in WSNs.
+
+\section{Evaluation Tools}
+On the one hand, several proposed works in WSNs require evaluating the power depletion efficiently and accurately for network lifetime prediction. On the other hand, the wrong energy evaluation leads to waste of energy because the sensor nodes might be rendered useless long time before draining their energy. Furthermore, the sensor nodes might die before of the expected lifetime. However, evaluation experiments on actually deployed WSN suffer some constraints because of the large number of sensor nodes and the deployment in hostile and inaccessible environments. Moreover, the analytical (or theoretical) models might be unrealistic for real world systems.