Institute of Advanced Engineering and Science w w w . i a e s j o u r n a l . c o m International Journal of Information & Network Security (IJINS) Vol.2, No.2, April 2013, pp. 183~189 ISSN: 2089-3299  183 Journal homepage: http://iaesjournal.com/online/index.php/ IJINS Directional Antenna Assisted Scheme to Reduce Localization Error in Wireless Sensor Networks Tarun Dubey, O.P. Sahu Department of Electronics and Communication Engineering, National Institute of Technology, Kurukshetra- India. Article Info ABSTRACT Article history: Received Nov 30 th , 2012 Accepted Dec 10 th , 2012 The existing omni directional antenna assisted schemes for localization of sensors in wireless sensor networks (WSNs) are not very accurate due to various constraints, since issues like sensor distribution, topology control; high cost and localization error obstruct the effectiveness of these algorithms and schemes. This paper presents a modified High Resolution Robust Localization (HiRLoc) scheme assisted by a single beam directional antennas for improving the localization in WSNs. Simulation result show that the proposed modified scheme estimates the position of more number of sensor with less average localization error compared to some existing schemes. Keyword: Average localization error Directional antenna Locator nodes Sensor nodes WSNs Copyright © 2013 Institute of Advanced Engineering and Science. All rights reserved. Corresponding Author: Tarun Dubey Department of Electronics and Communication Engineering National Institute of Technology, Kurukshetra, India, 136119 Email: tarundubey79@yahoo.co.in 1. INTRODUCTION The rising research interest in the area of WSNs during the past years has enabled many innovative and advanced applications [1]-[4]. These applications require precise location knowledge of sensors sometimes within meters, and at other occasions within a few centimeters [5]-[6]. The algorithms pertaining to localization of sensors are a fundamental focus of researchers and have lead to the development of various positioning schemes in order to support multiple applications on a single wireless sensor network [7]-[13]. These schemes involve some special sensors termed as locators, anchors or beacons, they obtain their locations either manually or through a positioning device and thereafter the locations of other sensors within the network are estimated by interacting with these special sensors and information either related to distance, range or angle is obtained [14]-[15]. The existing schemes provide services, privileges and trust towards the design of WSNs [16-17], but unfortunately fail to broadly highlight issues related to the localization error in WSNs [18]-[20]. This paper presents a modification to the existing HiRLoc scheme [19] assisted by single beam directional antenna for reducing the average localization error. The average localization error for centroid [18] and Secure Range Independent Localization (SeRLoc) [21]-[22] scheme is also evaluated. Simulation results show that the proposed scheme outperforms the above discussed schemes and offers more number of sensors to estimate their positions with less average localization error. The remainder of the paper is organized as follows. In Section 2, we discuss the assumptions for our network and directional antenna model. Section 3 presents the modified algorithm. Simulation results of the proposed scheme and comparison of its performance with other existing schemes are presented in Section 4. Section 5 concludes the paper. 2. ASSUMPTIONS This section describes the assumptions for the proposed scheme in terms of network model and the directional antenna model.