Exploitation of Modernized GPS Crosslinks to Improve User Integrity and Availability with ARAIM

Sukrut Oak, Sam Pullen, Sherman Lo, Juan Blanch, Todd Walter, Mark Crews, Robert Jackson, and Charles Frey

Peer Reviewed

Abstract:	In previous work, we introduced the concept of augmenting GPS with inclined geosynchronous satellites (I-GEOs) and Low Earth Orbit satellites (LEOs) that would provide GPSBlock-III-quality military and civil ranging signals along with conveying Satellite-based Augmentation System (SBAS) messages to users [1], [2], [3], [4]. This paper shifts the focus of that work by investigating the benefits of modernized GPS crosslinks, which allow satellites to exchange navigation data directly, reducing onboard Age of Data (AoD) and improving real-time positioning accuracy. For each arrangement of crosslink architectures, the Stanford MAAST GNSS simulation software package is used to evaluate the impact of crosslink-enabled data dissemination on protection levels (error bounds) for ARAIM users that would apply to military or civil aviation IFR approaches (such as LPV approaches) for ARAIM users without differential corrections. We present a comparative analysis of baseline GPS performance versus crosslink-enabled architectures, examining the reduction in Age of Data (AoD) and the consequent reductions in User Range Accuracy (URA) and User Range Error (URE) by showcasing improvements in horizontal and vertical protection levels (HPL, VPL). These results establish the extent to which crosslinks can enhance integrity and availability for ARAIM users, identifying key design factors for future GPS crosslink implementations. By reducing data latency across the satellite network, crosslinks provide an operationally viable means of improving GPS resilience.
Published in:	2025 IEEE/ION Position, Location and Navigation Symposium (PLANS) April 28 - 1, 2025 Salt Lake Marriott Downtown at City Creek Salt Lake City, UT
Pages:	226 - 234
Cite this article:	Oak, Sukrut, Pullen, Sam, Lo, Sherman, Blanch, Juan, Walter, Todd, Crews, Mark, Jackson, Robert, Frey, Charles, "Exploitation of Modernized GPS Crosslinks to Improve User Integrity and Availability with ARAIM," 2025 IEEE/ION Position, Location and Navigation Symposium (PLANS), Salt Lake City, UT, April 2025, pp. 226-234.
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