Using the Future L-band Communication System for Navigation

Abstract

Currently, aeronautical communications and navigation are undergoing a major renovation process. In navigation, GNSS (Global Navigation Satellite System) is in preparation to be used for area navigation and development/research is in progress to use GNSS for take-off and landing (up to CAT III) as well. The drawback of GNSS is its inherent single point of failure – the satellite. Therefore, an alternate solution for the GNSS failure case has to be available, known as APNT (Alternate Positioning, Navigation, and Timing). A possible APNT solution is to increase the density of DME stations and perform multi-lateration for positioning/navigation. This approach might have a severe impact on the use of the L-band for communications, since it leads to a much heavier use of the L-band spectrum by DME than today and it becomes more complicated to find the spectrum needed for future communications in L-band. Another approach towards APNT is to integrate a positioning/navigation function into the new L-band communication system, e.g. into L-DACS1 (L-band Digital Aeronautical Communication System, Type 1). This way, APNT is covered by L-DACS1 and additional DME ground stations are not necessary. In addition, if it is shown that L-DACS1 can reliably cover the positioning/navigation function, partial removal of DME ground stations might be possible. This would result in reduced ground infrastructure costs and increased spectrum capacity available for communications in L-band.

In the final paper, we propose an approach how positioning/navigation can be performed using L-DACS1. For this approach, we have already set-up a simulation environment and currently perform simulations and theoretical analysis. The first results based on Cramer Rao Lower Bound (CRLB) calculations are very promising. The CRLB indicates that the position error in three-dimensional space can be kept below 10 meters if a sufficient number of ground stations is considered for the ranging measurements. Final results from the theoretical analysis and the computer simulations are presented and discussed in the final paper.