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Academic Editor:Feng Hong
Department of Computer Science and Information Engineering, Inha University, Room 1403, Hi-Tech Building, 100 Inha-ro, Nam-Gu, Incheon 402-751, Republic of Korea
Received 27 February 2014; Revised 28 June 2014; Accepted 28 June 2014; 27 August 2014
This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
1. Introduction
In recent decades, positioning systems such as GPS, dead reckoning techniques, and intensively installed RFID tags have been used to localize a user continuously. Although GPS localization is a popular method, it is not suitable for pedestrians since the accuracy of GPS data is relatively low (more than 10 m). Therefore, we propose a more accurate localization method using the signal strength between ZigBees, instead of GPS.
We use range-based ZigBee as landmarks and apply trilateration using wireless sensor network with those nodes to estimate the position of the user. Although arranging of the numerous landmarks improves the accuracy of localization, it increases the cost. Accordingly, we propose an efficient localization method using minimum Bayes error estimation for optimal placement by generating and modelling the signal. In order to verify the availability of the proposed method, we applied it to a guidance system for visually impaired person that was developed in our previous studies [1]. As a result, the method helps pedestrians arrive at their destination safely.
We summarize related research in Section 2. In Section 3, we describe the ZigBee-based localization method and the optimal placement of sensors in detail. In Section 4, we present the experimental results while applying the proposed method to the prototype system. Finally, we conclude our study in Section 5 and discuss future work.
2. Related Works
Localization methods can be categorized according to the underlying wireless-communication systems such as methods using Wi-Fi, ZigBee, and UWB (Ultra wideband) [2-5]. In addition, these methods are classified into several types depending on the implementation method such as Cell-ID location technique, screen analysis method, triangulation, and stochastic modelling method [6, 7].
While using Wi-Fi, it is unnecessary to install other devices and it provides position data because of the access points (APs) that have been...