A Coverage Analysis Methodology for APNT Pseudolite Ground Network

Euiho Kim

Abstract:	The Federal Aviation Administration (FAA) is looking into a robust Alternative Positioning, Navigation, and Timing (APNT) solution that can provide seamless operation from en route to non-precision approach during expected and unexpected outages of the Global Navigation Satellites System (GNSS). A promising alternative of FAA’s APNT architecture is a pseudolite-based ground network that utilizes the existing infrastructure of widespread Distance Measuring Equipment (DME) and Automatic Dependent Surveillance –Broadcast (ADS-B) Ground Based Transceivers (GBT) over the Contiguous United States (CONUS). However, the technical and economic feasibility of the proposed APNT architecture against the intended operation has not been assessed. To evaluate the feasibility of the pseudolite-based APNT architecture, one method is to conduct a coverage analysis that shows the accuracy and integrity performance trade-off between ranging accuracy and user-to-ranging source geometry. From this analysis, a system developer would be able to see the level of ranging signal accuracy, the required number of ground stations, and the network lay-out. This paper discusses the formulation necessary to evaluate the coverage analysis against the APNT accuracy and integrity requirements and the typical coverage limitations resulting from the requirements. Additionally, given an existing DME/GBT infrastructure in select CONUS regions, the coverage differences with respect to varying levels of ranging accuracy are investigated to determine the level of ranging accuracy that yields the desired coverage. Further, a systematic strategy is presented to determine the placement of additional ground stations in optimal locations of an existing DME/GBT infrastructure to fill in APNT coverage gaps. The result from this systematic ground station placement strategy will provide the required number of additional stations and network geometry in the selected areas.
Published in:	Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011) September 20 - 23, 2011 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	495 - 507
Cite this article:	Kim, Euiho, "A Coverage Analysis Methodology for APNT Pseudolite Ground Network," Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011), Portland, OR, September 2011, pp. 495-507.
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