The main objective of this activity is to investigate innovative navigation algorithms exploiting FGO, both for a standalone GNSS unit and in combination with other sensors (INS), and for different receiver grades (including high- and low-quality modules). The activity will benchmark both the potential accuracy improvement and the computational cost of the proposed algorithms (in view of realtime implementations). This objective will be achieved via the design and implementation of a software-based FGO navigation (FGO-Nav) module that will be integrated in a flexible proof-of-concept (PoC) testbed composed of at least two GNSS receivers (a low-end and a high-end receiver) and an INS.