Quasi-Pilot Signals: Improving Sensitivity and TTFF without Compromises

Matteo Paonni, Marco Anghileri, Diana Fontanella, Bernd Eissfeller

Abstract:	The scope of this paper is to present the new concept of Quasi-Pilot signals. The solution here proposed is designed specifically for the Galileo E1-OS signal to replace the E1-C component, but as it will be shown could be easily extended to any satellite navigation signal. The paper starts with a review of the Galileo E1-OS signal structure, properties and a short assessment of its performance, in order to better point out the objectives aimed by the introduction of the Quasi-Pilot concept. In the successive section this concept is introduced and its properties and characteristics are deepened. In particular it will be explained that the primary goal is to optimize the Galileo E1-OS signal structure in order to solve one of its major shortcomings, and namely the long waiting time for retrieving the system time reference from the I/NAV message. As it will be shown the intended solution is to transmit on the current pilot channel a data message at a very low data rate containing just the system time reference. The Quasi-Pilot message will be shown to be 100% predictable and therefore, once achieved fine-time synchronization, the receiver can perform a wipe off of the predicted symbol sequence and use the Quasi-Pilot as a pure pilot signal, with all the benefits when tracking data-less signals. The design of the signal will be presented considering different configurations each with a different level of impact on the current Galileo E1-OS signal structure. A specific section is also dedicated to the issue of secondary codes, discussing the opportunity of adding a secondary code on top of the Quasi-Pilot symbols with the scope of aiding the symbol synchronization and increasing the CDMA isolation among the codes. In the last two sections the receiver architecture modifications to include the Quasi-Pilot is presented and a complete signal performance assessment is provided, where it will be demonstrated that impact on the Galileo signal structure and the implications for the receiver design are minimal. The paper is concluded with some considerations on the concept itself and the obtained results.
Published in:	Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011) September 20 - 23, 2011 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	1254 - 1263
Cite this article:	Paonni, Matteo, Anghileri, Marco, Fontanella, Diana, Eissfeller, Bernd, "Quasi-Pilot Signals: Improving Sensitivity and TTFF without Compromises," Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011), Portland, OR, September 2011, pp. 1254-1263.
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