A system engineering tool for the optimisation of a GNSS constellation design

This paper introduces a system engineering tool for the optimisation of a generic GNSS constellation design by using Galileo as reference. The optimisation is performed by taking into account both the percentage of global coverage and the accuracy in the position determination. The tool executes the optimisation not only for nominal and ideal cases, but also for off-nominal configurations involving catastrophic or transient failures of the constellation satellites. The analysis of the GNSS robustness to failures changes considerably the number of satellites to be used per plane with respect to the original configuration designed in nominal conditions.