Improved Positioning techniques for positioning based on raw GNSS measurements from smartphones

User’s location is a crucial information for a large number of applications installed on our smartphones. It is no coincidence that Google is constantly working on strategies to improve the position and that today manufacturers are mounting modern GNSS chipsets with increasing performances from this point of view. Access to Android GNSS raw measurements are the most interesting tool among those introduced as they allow developers to implement their own strategies to get location. Moreover, some smartphone models can decode the navigation message from the satellites broadcasted signal, meaning that it could be possible to evaluate the user’s position independently from the network. The theoretical capabilities of these new technologies can be compared to those of expensive high-precision GNSS receivers and the applications could be various. The goal of this thesis is to analyse in depth if the promised results can be achieved in real applications and if nowadays smartphones can really act as GNSS receivers. In the first part of this work the main concepts of GNSS are explained; followed by an analysis of the raw measurements and their performance in the second part. Then, several strategies and algorithms to improve measurements quality and positioning performance are implemented and tested, with a detailed description of the developed strategy to decode the GPS Navigation Message coming from the Android API. In addition, some tests were performed to implement a multi-GNSS constellation system, the results of which are presented.