Galileo high accuracy service: initial definition and performance

The Galileo High Accuracy Service (HAS), aiming at providing a Precise Point Positioning (PPP) service worldwide, will soon transmit precise orbits, clocks and biases, for both Galileo and GPS, in the signal-in-space and through a ground channel. This will be complemented in the future with precise ionosphere corrections and HAS data authentication. This work provides an overview of Galileo initial HAS, focusing on its overall message structure, architecture, and early performance. The initial HAS is strictly based on the existing Galileo monitoring and uplink capabilities already available for the other Galileo services. This contribution assesses the service coverage, the accuracy of the broadcast corrections, and the user PPP performance of Galileo HAS for the first time. The results show that Galileo HAS can provide broad coverage with few-centimeter broadcast correction accuracy and fulfill the targeted two-decimeter user horizontal accuracy in the evaluated conditions even in its initial phase.