Ad-hoc Wireless Sensor Positioning in Hazardous Areas

This paper investigates the capability of GNSS aided smart sensor network positioning based on Wireless Local Area Network (WLAN) signals incorporating access points, to monitor 3D deformation associated with volcanic activity and other comparable hazardous events. While a small number of GNSS receivers provide the coordinate and time references, low-cost low-power wireless sensor nodes with ranging capabilities create a dense positioning network. The simulations presented in this paper are based on a novel positioning algorithm that is robust with respect to errors in the inter-node range measurements. Based on a fine digital surface model of the Sakurajima volcano, various scenarios for setting up a monitoring network are assessed. The optimal number and location of nodes is determined for a future deployment of such a wireless sensor network. Results show that 2D positioning accuracy is to be expected in the magnitude of the mean range observation error. However, the crucial height component exhibits twice the error variance compared to the horizontal component. This is due to the poor geometric configuration in relation to height that is intrinsic to a ground based network.