November 17, 2014
Phd Thesis by Ms. Olga Segou, National Technical University of Athens, October 20th, 2014
Title: “Location-Based Services in indoor environments”.
Within this work, a software system focusing on the simulation of location estimation processes was implemented. The Locus software platform is based on the accurate simulation of the indoor channel and a variety of localization algorithms. It integrates a large number of algorithms across many fields and disciplines such as Wireless Propagation, Computational Geometry, Signal Processing, Location Estimation, Pseudorandom Number Generation, Exploratory Data Analysis and Probabilistic Modeling, etc. thus comprising a unique analytical framework. Empirical results from the deployment of three real-time localization systems based on the ZigBee, RFID and Chirp Spread Spectrum specifications are also herein presented. The implementation of the protocol stack of the ZigBee based system is thoroughly discussed, as it details the basic software components and sheds light on the common pitfalls that should be avoided in order to successfully reach the end-result of a fully functioning system. A large number of empirical measurements is collected in a variety of deployments for all three systems, in order to estimate their performance capabilities. Results are shown to align with previous conclusions drawn by extensive simulation and include the implementation of a noval topology-based smoothing method. This method is also shown to significantly improve the performance of all trilateration-based systems.