Optimized Multilevel CDMA Chip Design With Respect to Payload and User Constraints

Abstract

In a future multi-layered satellite navigation architecture, combining global navigation satellite systems (GNSS) with low earth orbit (LEO) satellites, substantial performance improvements of positioning, navigation and timing (PNT) are expected within the next decade. This has renewed interest in navigation signal design, since the signals need to be capable of delivering the improved performance to the user on ground. While the signals currently broadcast by GNSS have been designed with limited consideration of inherent payload and receiver distortions, it is promising to consider a comprehensive signal design approach that considers the distortions that occur in the transmitter and receiver hardware, which otherwise would adversely affect the performance of a PNT system. This work briefly highlights previously explored signal design concepts and extends the framework of multilevel coded spreading symbol (MCS) optimization in a way that attains a specified target performance in the presence of a set of payload and user constraints, all cast into one comprehensive optimization problem. The results show that a distortion-aware signal optimization process leads to more feasible and robust navigation signal designs that reliably increase user benefits in terms of tracking error jitter, but also differential range bias.