Clustered-based wireless sensor networks have been extensively used in the literature in order to achieve considerable energy consumption reductions. However, two aspects of such systems have been largely overlooked. Namely, the transmission probability used during the cluster formation phase and the way in which cluster heads are selected. Both of these issues have an important impact on the performance of the system. For the former, it is common to consider that sensor nodes in a clustered-based Wireless Sensor Network (WSN) use a fixed transmission probability to send control data in order to build the clusters. However, due to the highly variable conditions experienced by these networks, a fixed transmission probability may lead to extra energy consumption. In view of this, three different transmission probability strategies are studied: optimal, fixed and adaptive. In this context, we also investigate cluster head selection schemes, specifically, we consider two intelligent schemes based on the fuzzy C-means and k-medoids algorithms and a random selection with no intelligence. We show that the use of intelligent schemes greatly improves the performance of the system, but their use entails higher complexity and selection delay. The main performance metrics considered in this work are energy consumption, successful transmission probability and cluster formation latency. As an additional feature of this work, we study the effect of errors in the wireless channel and the impact on the performance of the system under the different transmission probability schemes.

ABSTRACT:Wireless sensor networks are composed by a big number of autonomous nodes surveying a certain environmental parameter, such as temperature, humidity or even mobile targets. In this work, we focus on mobile target detection in wide area systems such as tracking animals in a forest or vehicle detection in security missions. Specifically, a low energy consumption clustering protocol is proposed, analyzed and studied. To this end, two communication schemes, based on the well-known LEACH protocol are proposed. The performance of the system is studied by means of a mathematical model that describes the behavior of the network under the most relevant parameters such as coverage radius, transmission radius, and number of nodes inside the network. Additionally, the transmission probability in the cluster formation phase is studied under realistic considerations of a wireless channel, where signal detection errors occur due to interference and noise in the access channel. RESUMEN:Las redes inalámbricas de sensores están compuestas por un gran número de nodos autónomos que vigilan algún parámetro del ambiente de interés, como puede ser la temperatura, la humedad o incluso objetivos móviles. Este trabajo se enfoca en la detección de móviles en áreas amplias como puede ser la vigilancia de animales en un bosque o la detección de vehículos en misiones de seguridad. Específicamente, se propone, analiza y estudia un protocolo de agrupación de bajo consumo de energía. Para ello, se presentan dos esquemas de comunicaciones basados en el bien conocido protocolo LEACH. El desempeño del sistema se estudia por medio de un modelo matemático que describe el comportamiento de la red bajo los parámetros más relevantes, como son: radio de cobertura, radio de transmisión y número de nodos en la red. Adicionalmente, se estudia la probabilidad de transmisión en la fase de formación de grupos bajo consideraciones realistas de un canal inalámbrico, en donde la detección de la señal tiene errores debido a la interferencia y ruido en el canal de acceso.