Carrier-Phase Indoor Positioning Using Sliding-Window Estimation with a Single Array Beacon

Seongjin Park, Changdon Kee

Abstract:	This paper presents a carrier-phase-only three-dimensional indoor positioning algorithm using a single compact overhead beacon array. In a conventional single-array-beacon configuration, carrier phase provides accurate line-of-sight information but does not make the vertical component observable at a single epoch. To overcome this limitation, the proposed method formulates the problem as a sliding-window batch estimator in which the user height is treated as a shared state across multiple epochs. The method relies on two short-term physical constraints: approximately constant user height and locally linear receiver clock drift. A Levenberg–Marquardt (LM) solver is applied to the nonlinear batch least-squares problem, and warm-start initialization is used for continuous estimation. To match the actual implementation, the batch state is defined as [x1:Kw , y1:Kw , z, B0, b1] T and the Jacobian explicitly reflects the shared-state structure of z, B0, and b1. In addition, the measurement model is derived from the raw carrier phase including transmitter clock error, followed by receiver differencing with a fixed reference station to eliminate asynchronous pseudolite clock terms. Simulation and experimental results show that the proposed method substantially improves three-dimensional positioning performance relative to a snapshot least-squares solution and makes height estimation feasible without an auxiliary height sensor.
Published in:	Proceedings of the ION 2026 Pacific PNT Meeting April 13 - 16, 2026 Hilton Waikiki Beach Honolulu, Hawaii
Pages:	474 - 485
Cite this article:	Park, Seongjin, Kee, Changdon, "Carrier-Phase Indoor Positioning Using Sliding-Window Estimation with a Single Array Beacon," Proceedings of the ION 2026 Pacific PNT Meeting, Honolulu, Hawaii, April 2026, pp. 474-485. https://doi.org/10.33012/2026.20599
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