Design and Silicon Area Optimization of Time-Domain GNSS Receiver Baseband Architectures

The use of Global Navigation Satellite Systems (GNSSs) in a wide range of portable devices has exploded in the recent years. Demands for a lower cost while expecting longer battery life and better performance are constantly increasing. The general GNSS receiver operation and algorithms are already well studied in the literature, but the hardware architectures and designs have not been discussed in detail.This thesis introduces a high level gate count estimation method that provides good accuracy without requiring the hardware being fully specified. It is based on developing hierarchical models, which are parameterizable, while requiring minimal amount of information about the silicon technology used for the implementation. The average accuracy has been shown to be 4%.Three time-domain, real-time GNSS receiver baseband architectures are described with a discussion about various optimization methods for efficient implementation: the correlator, the matched filter, and the group correlator, which is a new architecture combining some of the features of the two first ones.Four use cases are defined for different GNSS operating modes: Acquisition, tracking, assisted GNSS, and the combination of the first three modes. A comparison is made for receiver basebands including all necessary blocks for full functionality to find out which of the three architectures provides the most silicon area efficient implementation.It is shown that the correlator offers good flexibility, but yields the highest silicon area for acquisition use cases. The matched filter is best suited for the acquisition, but has large overhead when it comes to tracking the signals. The group correlator offers a reasonably good flexibility and area efficiency in all use cases.The main contributions of the thesis are: Development of domain specific optimizations for GNSS receivers and an accurate gate count estimation method, which are applied for a quantitative comparison of different GNSS receiver architectures. The results show that no single architecture excels in all cases, and the best choice depends on the actual use case