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Recently wireless sensor networks (WSN) became an interesting topic because of its increasing usage in many fields; medical systems, environment monitoring, military applications and video surveillance. Usually sensors are placed in the desired locations to gather information frequently and then transfer it to the observers. WSN consists of a collection of application specific sensors, a wireless transceiver and a simple general purpose processor. In heterogeneous wireless sensor network, researchers found many challenging issues including the limited energy, the efficient usage of the energy, and the problem with the hierarchy of the network as imbalance network. Many studies indicated that the node clustering is a promising solution for such issues. Clustering has been shown to increase the efficacy of the energy consumption where clusters are formed dynamically with neighboring sensors and the power is assumed to be distributed equally among nodes. One of the nodes is considered as the cluster head that is responsible for transferring data among the neighboring sensors. In this work, we propose a modification based on SEP protocol. EM-SEP aims to prolong the stable period of the sensor network by maintaining balanced energy consumption. This means that we choose the advanced nodes to become cluster heads more often than the normal nodes as the case with SEP protocol. Furthermore, EM-SEP takes in account the number of nodes that are associated with each cluster head. Another important enhancement of EM-SEP protocol that if there are more than one sensor available to be a cluster head at certain round, we choose the sensor with highest energy. |
