Oversampling Limits for Binary Offset Carrier Modulation for the Acquisition of Galileo Signals

Code and frequency acquisition are important stages of today’s satellite systems, such as the European system Galileo. Newly proposed modulation types, such as Binary Offset Carrier (BOC) modulation, have triggered new challenges in the acquisition process. The features and properties of BOC-modulated code sequences are still not wellunderstood in the context of fast acquisition algorithms. Moreover, no research studies have been dedicated so far to the effects of oversampling in the presence of BOCmodulated pseudorandom signals. However, the oversampling factor is typically dictated by hardware limitations, and cannot be assumed to be always equal to unity. In this paper, we study the effects of oversampling on the BOCmodulated pseudorandom codes during the CDMA code acquisition process. We also focus on the design of the code-Doppler bin size and we give the conditions to be fulfilled in order to achieve good detection probabilities and low mean acquisition times. Simulation results are shown for realistic signals of the Galileo satellite system.