Detecting GNSS Spoofing by Decomposition of the Complex Cross Ambiguity Function with Extended Coherent Integration Time

Sahil Ahmed, Samer Khanafseh, and Boris Pervan

Abstract:	In this paper, we present, implement, and validate a method for decomposing spoofed Global Navigation Satellite System (GNSS) signals into their constituent components using Complex Cross Ambiguity Function (CCAF) decomposition [1]. We leverage longer coherent integration times to mitigate the effects of thermal noise in the measurement space. The CCAF decomposition, when integrated with direct positioning and inverse Receiver Autonomous Integrity Monitoring (RAIM), facilitates the separation of authentic and spoofed signals [2]. Subsequently, we identify the spoofed signal set, exclude it, and generate an authentic GNSS navigation solution aided by Inertial Navigation System (INS) measurements [3]. The method is applicable to spoofing scenarios that can lead to Hazardous Misleading information (HMI) and are difficult to detect by other means. It can identify spoofing in the presence of multipath and when the spoofing signal is power matched and offsets in code delay and Doppler frequency are relatively close to the true signal. Spoofing can be identified at an early stage within the receiver and even applicable for dynamic users.
Published in:	Proceedings of the ION 2024 Pacific PNT Meeting April 15 - 18, 2024 Hilton Waikiki Beach Honolulu, Hawaii
Pages:	671 - 686
Cite this article:	Ahmed, Sahil, Khanafseh, Samer, Pervan, Boris, "Detecting GNSS Spoofing by Decomposition of the Complex Cross Ambiguity Function with Extended Coherent Integration Time," Proceedings of the ION 2024 Pacific PNT Meeting, Honolulu, Hawaii, April 2024, pp. 671-686. https://doi.org/10.33012/2024.19628
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