This thesis will try to further increase the accuracy of a mixed GNSS and inertial solution for navigation in urban areas. The mix will represent a set of low cost sensors to mea-sure their performance. The objectives will be the implementation of a multi-constellation GNSS receiver, and the research and test of modelling techniques for GNSS measure-ments based on carrier-to-noise ratio. Any other technique that allows for an increase in the accuracy will also be used and tested. The laboratory work for this thesis will be done at l'Ecole Nationale de l'Aviation Civile as part of an exchange program. First of all the theoretical studies will be carried out, first of stand-alone GNSS and INS navigation and then on their integration. This integration will consist on the use of a Kalman Filter algorithm, and therefore additional theory on the implementation of this filter will be necessary. Then the current algorithm developed by ENAC is analysed, together with the hardware connection requested with the different equipment. A measurement campaign was done to collect new samples from ENAC at the outskirts of Toulouse to the city center. Data was then post process several times to obtain the most optimal configuration for the receiver in urban and suburban environments. The re-sults showed that the implementation of GLONASS together with the suggested weighting modelling based on carrier-to-noise level measurements allowed an increase of almost 50% in the accuracy of the position and the estimation of the yaw.