Toward centimetric positioning thanks to L- and S-Band GNSS and to meta-GNSS signals

RDSS downlink bands, usually with a paired uplink, could be used, like RNSS bands, for satellite navigation. The eventual need for additional Galileo frequencies and signals in S-band or C-band in addition to those currently used is not only about improving the pseudoranging or timing performance, but primarily about introducing new services. Another very important field recently studied to improve accuracy worldwide, is Integer Ambiguity Resolution on Undifferenced Phase which could allow very precise positioning accuracies close to a few cm in real time when permanent phase tracking is maintained on at least two carrier frequencies at the same time. Since cycle slip could occur on a carrier at a given dates, at least 3-carrier tracking is required to ensure robustness for such PPP techniques. In this paper, this last concept of integer ambiguity resolution together with the introduction of new signals/services at S-Band will be studied. The new functions/services specifically provided by a satellite navigation signal at S-band could be also complementary to already existing LEO mobile telecommunication constellations. In this paper it is shown how S-band GNSS signals in addition to the actual L-band signals could also improve the robustness and accuracy, by easing significantly the Integer Ambiguity Resolution on Undifferenced Phase process, combining two fundamental concepts. The first concept introduced in the paper is based on the following finding: if a GNSS system has two signals transmitted at two carrier frequencies that are multiple one of the other, then the wide lane carrier phase ambiguity resolution can be eased a lot. The second concept is the one of “Meta-GNSS signals”. The basic idea consists of processing two different GNSS signals transmitted at different carrier frequencies as a single signal thanks to an AltBOC processing. As it is shown in the paper, these two concepts combined together could therefore allow a robust quasi-centi- - metric “absolute” positioning, worldwide, thanks to a possible new Galileo signal added at S-band frequencies. The paper details these two concepts and their related area of research, and presents preliminary possible S-band signal designs accordingly.