Optimized Ground Segment Scheduling and URE Performance Analysis for Regional LEOPNT Architecture

Kihyun Kim, Donguk Kim, Sunjin Kim, O-Jong Kim

Peer Reviewed

Abstract:	Global Navigation Satellite Systems (GNSS) in Medium Earth Orbit (MEO) support many critical services, but their weak received power makes them vulnerable to radio frequency interference. By contrast, Low Earth Orbit (LEO) satellites can provide stronger signals that penetrate indoors and dense urban environments. Using only LEO signals is therefore a promising approach to complement or back up GNSS and has led to active research on LEO-based Positioning, Navigation, and Timing (PNT) systems. LEO-PNT is generally categorized into Signals of Opportunity (SoOp) and Dedicated approaches; this study focuses on the Dedicated case, where maintaining the signal-in-space User Range Error (SIS URE) and onboard clock performance within target levels is critical. Building on these points, prior work proposed and analyzed a regional LEO-PNT concept that explicitly applies several key design factors. The essential design factors of a regional LEO-PNT system include constellation configuration defined by altitude, inclination, and Walker pattern, onboard clock type, and the availability of inter-satellite links and onboard GNSS receivers. Collectively, these factors determine satellite visibility, time synchronization capability, and the level of independence from ground infrastructure. Unlike many prior works assuming global coverage, the focus here is on regional systems that allow reduced satellite transmit power, smaller platforms, and lower unit cost, offering both operational and economic benefits. Within this framework, the underlying assumptions and parameters of the prior concept study are reexamined and updated, and a conservative set of values is applied, including a shift time for antenna repointing derived from azimuth/elevation travel rates and preparation margins. These conservative assumptions significantly reduce ground-to-satellite uplink opportunities, creating a constrained operating environment in which optimized scheduling is required to maintain SIS URE targets. To address this, a custom genetic-algorithm-based uplink scheduler is developed and compared with a greedy baseline across representative repointing-time regimes and antenna counts, and the analysis quantifies the impact on scheduling efficiency and SIS URE while identifying the minimum number of ground uplink antennas needed to guarantee stable regional LEO-PNT navigation performance.
Published in:	Proceedings of the 2026 International Technical Meeting of The Institute of Navigation January 26 - 29, 2026 Hyatt Regency Orange County Anaheim, California
Pages:	76 - 86
Cite this article:	Kim, Kihyun, Kim, Donguk, Kim, Sunjin, Kim, O-Jong, "Optimized Ground Segment Scheduling and URE Performance Analysis for Regional LEOPNT Architecture," Proceedings of the 2026 International Technical Meeting of The Institute of Navigation, Anaheim, California, January 2026, pp. 76-86. https://doi.org/10.33012/2026.20529
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