Publication: Analysis of trilateration method and distance approximation for planar coordinate position determination
Loading...
Date
2008-05-01
Authors
Wong, Siew Lean
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
The objective of this project is to analysis and design a Trilateration algorithm to determine the two dimensional position of the mobile entity. The solution proposed in this thesis is to treat the unknown position as the point of intersection of three spheres, whose centers are at known fixed positions. Understanding of difference between near field and far field characteristic for propagation is important to estimate the distances. An experiment on far field using radio beacon to measure the approximate distances between mobile entity and three base stations had been carried out. The study on the losses of signal strength when it travels through Line of Sight (LOS) is needed for precise distance measurement. The result from distance prediction tool is compared with the measurement result. Almost identical distance was observed. The mathematical solution used these approximate distances, and the coordinates of the known fixed base station positions, to calculate the position of the mobile entity. Two techniques for estimating accurately the position of a mobile entity in indoor environment with Trilateration was derived, L shaped configuration and iterative linear least squares estimators. Both of them are implemented using MATLAB‟s Graphic User Interface. The accuracy of L-shaped configuration‟s estimator had been examined in details. The core of the challenge is to understand the cause of errors in estimating the position of mobile entity. These ranging errors are due to distance measurement error (DME) and rounding error. As a conclusion, L-shaped configuration‟s estimator and distance prediction tool is highly reliable and accurate prediction tool.