Distortion-Aware Multilevel Coded Spreading Symbol Optimization for Future Navigation Signals

<title>Abstract</title> The navigation signals of global navigation satellite systems have undergone development with limited consideration given to inherent payload and receiver constraints. The forthcoming satellite generation will be equipped with flexible, fully digital payloads and feature enhanced clock architectures, which may offer potential performance improvements for positioning, navigation, and timing (PNT) users. A significant challenge is to realize these performance improvements at the user level while addressing distortions in transmitter and receiver hardware that impair PNT performance. This study reviews previous signal design concepts and extends the multilevel coded spreading symbol optimization framework to account for nonlinear and linear payload distortions and receiver band limitations. The proposed comprehensive distortion-aware optimization methodology yields signal candidates with enhanced robustness by improving performance metrics such as mean tracking error jitter and differential range bias, consequently delivering greater user benefits than signal designs optimized for minimally distortion-affected signal propagation scenarios.