Using Multi-Layer Perceptrons to Enhance the Performance of Indoor RTLS Dante I. Tapia, Javier Bajo, Juan F. De Paz, Ricardo S. Alonso, Sara Rodríguez and Juan M. Corchado Department of Computer Science and Automation, University of Salamanca Plaza de la Merced s/n, 37008, Salamanca, Spain {dantetapia, jbajope, fcofds, ralorin, srg, corchado}@usal.es Abstract. Accuracy in indoor Real-Time Locating Systems (RTLS) is still a problem requiring novel solutions. Wireless Sensor Networks are an alternative to develop RTLS aimed at indoor environments. However, there are some effects associated to the propagation of radio frequency waves, such as attenuation, diffraction, reflection and scattering that depends on the materials and the objects in the environment, especially indoors. These effects can lead to other undesired problems, such as multipath. When the ground is the main responsible for waves reflections, multipath can be modeled as the ground reflection effect. This paper presents a model for improving the accuracy of RTLS, focusing on the mitigation of the ground reflection effect and the estimation of the final position by using Neural Networks. Keywords. Applications of sensor and actuator networks, wireless sensor networks, real-time location systems, ground reflection effect. 1. Introduction Indoor Real-Time Location Systems (RTLS) are gaining relevance during the recent years and represent a currently growing market. The most important factors in the locating process are the kinds of sensors used and the techniques applied for the calculation of the position based on the information recovered by these sensors. Indoor locating (e.g., inside buildings or tunnels) needs still more development, especially with respect to accuracy and low-cost and efficient infrastructures [12; 15]. One of the main challenges is to deal with the problems that arise from the effects of the propagation of radio frequency waves, such as attenuation, diffraction, reflection and scattering. These effects can lead to other undesired problems, such as multipath. When the ground is the main responsible for waves reflections, multipath can be modeled as the ground reflection effect. Due to these effects, the energy of the transmitted electromagnetic waves is substantially modified between transmitter and receiver antennas in these systems. Therefore, it is necessary to develop Real-Time Locating Systems that allow performing efficient indoor locating in terms of precision and optimization of resources. EPIA'2011 ISBN: 978-989-95618-4-7 31