Position Tracking Using WI-FI Received Signal Strength

Abstract

The importance of services, based on current location of objects is swiftly increasing. Mostly, commerce and business activities are conducted inside buildings. Global Navigation Satellite System (GNSS) cannot provide object position inside buildings, since for object position determination GNSS not only requires direct line of sight to the object, but also GNSS signals are badly affected by multipath. In near future, the Location Based Services (LBS) will be tremendously dependent on Indoor Positioning System (IPS). In order to develop a 3D IPS based on Wi-Fi Received Signal Strength (RSS) in a heterogeneous environment, the following approach was used. Parallel RPROP and greedy algorithm were combined for development of IPS using Received Signal Strength (RSS) in heterogeneous environment, the environment comprised of human activity, walls' material, cupboards, and various type of surveying machines and equipment. The propagation of Wi-Fi signal varies directionally; therefore, to cope with direction changes in signals; our proposed model produces three sets of weights, which could be considered best for easting, northing and height, respectively. Our model was trained with 75% of collected data and tested on remaining 25% data. Distance error was used for accuracy assessment. Through our experiments, we achieved maximum accuracy of 0.87m and we came to know that median error was less than mean error. Median error were about 3.32m and the mean error was about 4.62m. Based on our results, we recommend the use of parallel RPROP and greedy algorithm for 3D position determination in heterogeneous environment.