Placing LDACS-based ranging sources for robust RNP 1.0 accuracy en-route

Abstract

Global Navigation Satellite Systems (GNSS) are becoming the primary means of navigation for civil aviation. Nevertheless, concerns about GNSS outages remain, driving the need for Alternative Positioning, Navigation and Timing (APNT) systems to provide availability and continuity for performancebased navigation services. Although the existing Distance Measuring Equipment (DME) infrastructure is able to provide Required Navigation Performance (RNP) 1.0 accuracy, it is not robust for individual station outages. Additionally, we show that in the European airspace DME is reaching the capacity limit. To address these two problems, we propose a methodology based on modular APNT. In the presented approach, the complementary ranging sources are optimally placed to obtain robustness. It is assumed that the L-Band Digital Aeronautical Communications System (LDACS) can provide this capability. As shown in the results, the modular APNT system is able to provide robust RNP 1.0 coverage for Germany using 17 new LDACS ground stations to complement the network of 73 existing DME installations in Germany.

New APNT ranging signals as an opportunity for rationalizing ground infrastructure

“…In this paper we present a modified version of methodology proposed in [4], which can be used to assess the impact of the new technologies at horizon on legacy DME navigation system. The deployment of new raging signals make it possible to decommission older radio navigation solutions.…”

“…In [4], we presented a optimization method to select sites from existing aeronautical navigation/communication network as potential locations for a new technology. We have shown that a hybridization of existing DME network with a better ranging system provides a robust RNP 1.0 accuracy over German airspace.…”

“…A short-term APNT infrastructure is based on Distance Measuring Equipment (DME) that fully support PBN operations based on RNP 1.0 navigation specifications, with an adequate network [3]. As shown in [4] and [5] there are three key limitations of current DME-based navigation network:…”

“…In [4], we assessed the robustness of DME network with leave-one-out fashion analysis: in order to account the ability to cope with dropped or faulted measurements. This analysis is similar to Receiver Autonoumous Integrity Monitoring (RAIM) commonly used in GNSS applications.…”

“…Therefore, the legacy DME network needs to be complemented, we take this as an opportunity to introduce ranging signals with a greater accuracy. In [4] we proposed a method to place the complementary stations. The hybrid solution, based on a combination of new ranging system and legacy DME, provides a robust RNP 1.0 accuracy.…”