Combining GPS and Galileo Signals Acquisition in a Single Processing Chain

Abstract

The increasing demand for accurate and efficient Global Navigation Satellite System (GNSS) receivers, especially in smartphones, has driven the need to combine multi-GNSS signals. Current receivers, based on Global Positioning System (GPS) and Global Navigation Satellite System (GLONASS) signals, often process these signals side-by-side, increasing complexity, size, and power consumption. Meanwhile, the next generation of smartphones and navigation applications will involve Galileo receivers to improve positioning accuracy, faster time to first fix, and reduce the multipath effect, especially in urban canyons or dense forests. Therefore, to avoid the drawbacks of side-by-side implementation; i.e. minimize the large size, and preserve processing time with low power consumption, this work presents a novel approach to simultaneously acquire GPS L1 and Galileo E1 signals in a single processing chain. This achieved by taking advantage of both GPS and Galileo signals are sharing the same carrier frequency and chipping rate. However, our solution requires just a single pre-processing step to overcome the subcarrier effect and one extra multiplication for the Galileo code. The results based on Monte Carlo simulation show that the combining solution; firstly, maintains the acquisition performance for each signal and has the same performance as acquiring each signal alone. Secondly, offers about 48% reduction in the implementation/computational complexity. Eventually, the solution preserves the reliability of the acquisition process by comparing the ratio of the highest peak to the average value in the correlation process, where the results illustrate that both GPS and Galileo signals have the same ratio tendency.