A Fine-Grained Localization Scheme Using a Mobile Beacon Node for Wireless Sensor Networks

Abstract

Abstract —In this paper, we present a fine-grained localization algorithm for wireless sensor networks using a mobile beacon node. The algorithm is based on distance measurement using RSSI. The beacon node is equipped with a GPS sender and RF (radio frequency) transmitter. Each stationary sensor node is equipped with a RF. The beacon node periodically broadcasts its location information, and stationary sensor nodes perceive their positions as beacon points. A sensor node’s location is computed by measuring the distance to the beacon point using RSSI. Our proposed localization scheme is evaluated using OPNET 8.1 and compared with Ssu’s and Yu’s localization schemes. The results show that our localization scheme outperforms the other two schemes in terms of energy efficiency (overhead) and accuracy. Keywords —Localization Algorithm, Mobile Be acon Node, Sensor Network, RSSI 1. I NTRODUCTION Wireless sensor networks (WSNs) are expected to be used in a wide range of applications, such as target tracking, military reconnaissance, habitat sensing, and fire detection [1, 2]. In most applications, sensed data without knowing the sensors’ location is meaningless. Localiza-tion must be considered as an implicit feature of a sensor network. This can significantly sim-plify network discovery and maintenance efforts and lead to substantial energy savings. The localization problem has received much attention in recent literature. Most of the current local-ization schemes are proposed to eliminate a GPS receiver on every sensor node. They suggest the use of a special type of nodes, “beacon nodes”, which know their absolute locations via GPS or manual placement. Other sensors can discover their locations based on information provided by these anchor nodes [3]. Several schemes, broadly classified into two categories range-based and range-free schemes, have been proposed to deal with the localization problem. Firstly, the range-based schemes need either node-to-node distances or the angles to estimate locations [5-8]. The information can be obtained using time of arrival (TOA), time difference of arrival (TDOA), angle of arrival (AOA), and the received signal strength indicator (RSSI) technologies [9, 10]. The range-based schemes typically have higher location accuracy but require additional hardware to measure the distances or angles. Secondly, several approaches based on range-free are proposed to determine senor