Designing and Performance Evaluation for an Indoor Location and Tracking System

Abstract

The goal of this paper is to present an improvement of our methods, presented at Rev2004 Conference, for positioning and tracking objects (laptops, PDAs) inside an 802.11b WLAN. We have modified the wrapi.dll for a facile data acquisition in LabVIEW and have passed over the entire application to LabVIEW due to its easier way of programming, possibilities for signal processing and a more facile information presentation. The positioning system operates by recording and processing signal strength information at multiple base stations positioned to provide overlapping coverage in the area of interest. We have used the signal strengths received from the WLAN base stations to build a radio map for the layout of the floor and have stored it in a database. The on-line phase the algorithm calculates the position of the mobile user, by comparing its actual unknown position (in signal strength space) with all the reference pointâ??s positions stored in the radio map, provides the best match and display the result on the laptop or PDA screen, in XY coordinates. Furthermore, we have implemented in LabVIEW some methods to compensate the errors produced due to walls, furniture reflections and human body diffractions. Also, experimental results and conclusions concerning the accuracy of a system for positioning and tracking objects (laptops) inside an 802.11b WLAN are presented.