A new algorithm of BOC multipath error simulation

Abstract

European GALILEO different from GPS will have more excellent positioning performance in accuracy for that a new modulation technique which is called the Binary Offset Carrier (BOC) modulation will be adopted in GALILEO. BOC modulation has a direct high efficiency in frequency occupation and in mitigation of interference. In the pseudo range measurement for high precision application, code tracking multipath error is one of the main error sources that can not be eliminated by Differential Global Positioning System(DGPS), and many testing and measuring results have shown that code tracking multipath error has become a dominating error source in the future Global Navigation Satellite System (GNSS) applications. This paper presents the code tracking multipath error of BOC signals in GALILEO and of L1 signal in GPS after analysis of several characteristics in time and frequency domain such as AutoCorrelation Function (ACF) and Power Spectral Density (PSD). The conventional ACF of GPS signals is expressed by the triangle shaped function, but the BOC signals have ACF with multiple peaks that result in the complexity of ACF expression in many intervals. This paper presents another expression with the ceil function to compute the theoretical code tracking multipath error for sine typed and cosine typed BOC signals. Compared with the traditional algorithm, the new algorithm can speed up the numerical solution of the tracking bias in simulation. The simulation results indicate that the antimultipatherror performance of cosine BOC signals is much better than that of sine BOC signals.