Enhanced Differential Correlation Method for the Acquisition of Galileo Signals

In this paper, we analyze an enhanced differential non-coherent integration method for the acquisition stage of a BOC-modulated CDMA signal in the new European Galileo satellite navigation system. This method, denoted by DN₂, offers an improved suppression of any temporally uncorrelated interferers. Background noise is naturally the most obvious source of temporally uncorrelated interference, but, for example, in CDMA systems, also a multiaccess interference is inherently very weakly time-correlated. Here, we carry out a comprehensive comparison between DN₂ method, the conventional non-coherent integration, and the traditional differential non-coherent integration methods. The correlation methods are compared and analyzed in fading channels, taking into account both ambiguous BOC and sideband based unambiguous technique (such as Betz&Fishman method). We also propose a combined algorithm, which chooses the best correlation method based on an estimation of the coherence time of the current channel