Hybrid APNT architecture using DME/DME and multilateration

DME/DME and Passive Wide Area Multilateration (P-WAM) are two proposed FAA´s Alternative Position, Navigation, and Timing (APNT) architectures that provide navigation and surveillance capability to National Air Space during a GNSS outage. Although Distance Measuring Equipment (DME) and Multilateration (MLAT) system operate in a very different way, they use the same frequency band and can share the same antenna, which allows for one system integrating DME and MLAT electronics. Similarly, Automatic Dependent Surveillance-Broadcast (ADS-B) can be integrated with DME and MLAT. This DME/MLAT/ADS-B integrated system in one cabinet can be used to simultaneously provide DME and MLAT service for navigation and ADS-B for surveillance. With this dual navigation service capability of the integrated system, it is possible to develop a hybrid APNT architecture enabling both of DME/DME and P-WAM service as a back-up of GNSS. The important advantage of the hybrid architecture is that the impacts on the avionics of General Aviation users and commercial jet airliners would be minimal by requiring only software and additional input/output connections. This paper describes the methodology and results for the feasibility study of the hybrid architecture and investigates the required ground station layout of the hybrid architecture that meets the anticipated APNT navigation and surveillance performance requirements by evaluating selected areas of the continental U.S. The required ground network will be determined through an optimization process called Coverage Analysis Method [1, 2] and be compared with the respective required ground networks for DME/DME and P-WAM based architectures to evaluate the additional number of ground stations needed in the hybrid architecture. In addition, the capacity of the DME/MLAT/ADS-B integrated systems in the hybrid architecture will be evaluated.