Coherent, Noncoherent, and Differentially Coherent Combining Techniques for Acquisition of New Composite GNSS Signals

The growing demand of location, navigation and positioning services is boosting the development of new signals and modulations that will be adopted by new Global Navigation Satellite Systems (GNSS), such as the European Galileo, the Chinese Compass and the modernized GPS. A common feature of these new modulations is the presence of two channels, the data and pilot components, that separately carry the navigation message and the ranging information. Three different techniques, noncoherent combining, coherent combining with sign recovery and differentially coherent combining, are analyzed for the joint acquisition of data and pilot signals. For each acquisition strategy the probabilities of detection and false alarm are provided. In particular closed-form expressions for the probabilities of coherent channel combining and of the differentially coherent integration strategy are derived. To the best of our knowledge these expressions are new. Monte Carlo simulations are used to support theoretical analysis demonstrating the accuracy of the proposed models.