Performance of a Galileo PRS/GPS M-Code Combined Service

Guenter W. Hein and José Ángel Ávila-Rodríguez

Abstract:	The agreement between the European Union and the United States of America on the promotion, provision and common use of the two satellite-based navigation systems GPS and Galileo has opened a new world of possibilities in satellite navigation. The combined use of Galileo and GPS civil signals has shown to bring a clear enhancement of performance in terms of positioning accuracy and navigation solution (see [1] and [2]) The compatibility and interoperability that the Galileo signal structure will offer with respect to GPS is especially relevant in the E2- L1-E1 band. After long negotiations, the United States and the European Union agreed on June 26th, 2004, on the Open Service (OS) signals to be transmitted by Galileo and the future GPS on L1. But if we look more in detail into the different waveforms, we see that not only the Galileo Open Service and the GPS C/A code have a common centre frequency on L1 but also the Galileo Public Regulated Service (PRS) and the GPS military Mcode. Since common centre frequencies are certainly the main prerequisite for interoperability, the combined processing of PRS and military signals from Galileo and GPS raises the possibility of offering a better positioning and navigation solution. Thus, in this paper we want to go one step further to the analysis made in [2] and we will assess the performance of a combined Galileo PRS and GPS M-Code receiver. There is no doubt that from a political and military point of view the problem of a combined Galileo PRS and GPS M-code service has not been addressed yet and probably it will require time-consuming and lengthy discussions in the future if the negotiations ever take place. However, it is certainly now the right moment and it makes sense to evaluate from a purely technical point of view the pros and cons as well as the performance that such a service could offer someday. Therefore, this paper first evaluates the performance of the two single services separately using identical assumptions. In order to do so, a refined methodology is proposed to estimate the different sources of error that contribute to the User Equivalent Range Error (UERE). Afterwards the same analysis is carried out for a combined processing of Galileo PRS and GPS M-code signals for a joint position, velocity and time solution. Finally, the pros and cons from a technical point for the manifold of possible combined receivers are outlined.
Published in:	Proceedings of the 2005 National Technical Meeting of The Institute of Navigation January 24 - 26, 2005 The Catamaran Resort Hotel San Diego, CA
Pages:	754 - 768
Cite this article:	Hein, Guenter W., Ávila-Rodríguez, José Ángel, "Performance of a Galileo PRS/GPS M-Code Combined Service," Proceedings of the 2005 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2005, pp. 754-768.
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