LDACS1 for an Alternate Positioning Navigation and Time Service

The future L-band Digital Aeronautical Communication System LDACS1 shows a very promising performance as a communication service. The system offers the possibility to also provide a navigation service with minimal adaptation. This paper investigates the level of performance achieved by an LDACS1 based navigation service. The results are outstanding and show that the stringent requirements of RNP0.1 can be reached in a large service volume. Two key parameters have a large impact on the performance of the navigation solution: the density of stations used as ranging sources and the time synchronization accuracy of these stations. The sensitivity of the performance to the second parameter has been investigated in this paper. It is shown that the time synchronization has significant impact on the achievable positioning performance only if the error is larger than 100 ns (one standard deviation). This is a very large synchronization error that can be easily reduced to 20 ns using existing low cost atomic clocks. The simulation results are very promising and open the doors to further investigations including flight experiments (planed in 2012), in particular the investigation of high performance and low cost system architectures that keep or improve the level of safety.