Procedia Chemistry www.elsevier.com/locate/procedia Proceedings of the Eurosensors XXIII conference Localization in Wireless Ad-hoc Sensor Networks using Multilateration with RSSI for Logistic Applications Xinwei Wang a, *, Ole Bischoff a , Rainer Laur a , Steffen Paul a a Institute for Electromagnetic Theory and Microelectronics (ITEM), University of Bremen, Otto-Hahn-Allee NW1, D-28359 Bremen, Germany Abstract A multilateration algorithm is presented in this work in order to realize a precise localization of the sensor nodes in wireless sensor networks in logistic applications. RSSI (Received Signal Strength Indicator) is used for distance measurements between sensor nodes. The developed algorithm is simulated and afterwards implemented in a real sensor network for food transportation logistic. The test results show that the multilateration algorithm with RSSI reaches the requirements of logistic applications. Keywords: Localization; Wireless Sensor Networks; Multilateration; RSSI; Logistic applications 1. Introduction When transporting perishable or sensitive freight, wireless sensor networks (WSN) can be used to monitor the environmental parameters in the container online 1 . WSN are appropriate to solve such logistic tasks due to their low energy consumption and simple applicability. The localization of the sensor nodes in WSN enables the assignment of sensor values, e.g. temperature and humidity, to their measuring points. Many studies about localization in WSN with different devices and algorithms were carried out 2,3,4 . The simplest method for a two dimensional localization is trilateration using distance measurements from an unknown sensor node to three non-linear anchors with known positions. To reduce the influence of distance errors on localization accuracy a multilateration algorithm with more than three anchors is used in this work. Firstly, the relationship between RSSI und distances is determined empirically. After optimizing the number of anchors in the WSN through a simulation with Matlab the localization algorithm is implemented in a WSN practically and the test results are shown in this paper. 2. Localization algorithms and distance measurement approaches Lateration and angulation are the two main localization algorithms. Lateration uses distances between the sensor nodes while the angulation determines the position based on angles 5 . Compared with angulation using specific * Corresponding author. Tel.: +49 421 218 2433; fax: +49 421 218 4434. E-mail address: wang@item.uni-bremen.de 1876-6196/09/$– See front matter © 2009 Published by Elsevier B.V. doi:10.1016/j.proche.2009.07.115 Procedia Chemistry 1 (2009) 461–464