Defensive performance evaluation methods of BDS-3 space segment oriented toward satellite navigation countermeasures

The electromagnetic environment is constantly changing. Compared to user-segment defense, the spatial satellite constellation, which is the core of the global navigation satellite system (GNSS), faces more complex threat sources and dynamic jamming scenarios. There is an urgent need for research on evaluating the defensive performance of GNSS in the space segment to ensure its built-in system updates, external facility maintenance, and system security applications. However, effectively evaluating the space-segment defensive performance poses challenges due to the limited existing studies in this field. Therefore, this study presented 25 different threat scenarios using BeiDou navigation satellite system III (BDS-3) as an example and introduced the concept of stability margin to improve existing models for assessing system service performance under non-threatening situations from various perspectives, including constellation status, navigation information quality, spatial signal quality, and service performance evaluation. Consequently, the itemized performance evaluation models of the space-segment defense were proposed for multi-threat scenarios. Furthermore, based on fuzzy comprehensive assessment principles, this study introduced an improved combined assigning method to enhance the weighted product approach, thereby proposing a comprehensive capability evaluation method for the space-segment defense. Experiments demonstrated that these proposed models efficiently determined stability margins against jamming threats for various performances in comparison to existing models, with higher sensitivity toward changes in threat intensity and closer to the theoretical threshold of 0.5. They have effectively assessed the space-segment defensive capability.