Abstract:Automatic driving has led to a great demand for global instantaneous high-precision precise point positioning (PPP). To achieve global instantaneous high-precision PPP, such as centimeter-level accuracy, global single-epoch narrow-lane (NL) ambiguity resolution (AR) is needed, which is quite difficult due to the limited accuracy of global atmospheric corrections. Multi-constellation and multi-frequency PPP wide-lane (WL) AR (PPP-WAR) provides a new approach to global single-epoch NL AR without atmosphere corrections because the instant NL ambiguity accuracies will be improved by fixing many WL ambiguities instantaneously. In this article, the uncombined PPP cascading WL/NL AR method (PPP-CAR) was extended to GPS, Galileo, BDS-2, and BDS-3 all-frequency signals to investigate global single-epoch NL AR with global public stations. The test results indicated that the instant positioning accuracies improved substantially with increasing frequencies for the single-epoch multi-frequency PPP-CARs, attributed to the contribution of the additional frequency observations. However, the same fixing rates of the NL ambiguities of 99.8% in all epochs were achieved for the single-epoch multi-frequency PPP-CARs, demonstrating that more reliable single-epoch NL ARs were reached with increasing frequencies. Only decimeter-level instant positioning accuracies were achieved for the dual-frequency, triple-frequency, and quad-frequency PPP-CARs. A centimeter-level global horizontal instant positioning accuracy of 0.07 and 0.08 m in the east and north components, respectively, was achieved by the five-frequency PPP-CAR for the first time. These results are very encouraging because better positioning is expected for global autonomous driving vehicles by integrating the multi-constellation all-frequency signals with other sensors, such as an inertial sensor.