Study on a Galileo Signal and Service Plan for C-band

Jose-Angel Avila-Rodriguez, Stefan Wallner, Jong-Hoon Won, Bernd Eissfeller, Andreas Schmitz-Peiffer, Jean-Jacques Floch, Enrico Colzi, Jean-Luc Gerner

Abstract:	Due to the great congestion that GPS, GLONASS and the future Galileo navigation signals will suffer on L-band, the additional application of a C-band (4-8 GHz) frequency band for navigation has always been under discussion since the beginning. However, C-band will only have a chance in the future if services which are not covered today by L-band can be provided by C-band either alone or in combination with other navigation frequencies or communication means. A first focus of this paper will thus be to identify potential services paying special attention to all the related signal aspects. The great congestion that current navigation services suffer today in the L-band has awakened in the past months the interest of the navigation community to look for new frequency allocations. One of those bands, namely C-band, deserves special interest as different Global Navigation Satellite Systems (GNSS), in particular Galileo, have either filed already for this band or are seriously planning to potentially make use of it in the future. The Galileo downlink C-band extends from 5010 MHz to 5030 MHz. This frequency slot has only a reduced bandwidth of 20 MHz available with very stringent limitations regarding the power emissions out of the band, especially on the Radio-Astronomy (RA) band. The RA band ranges from 4090 MHz to 5000 MHz. In addition, the Galileo C-band also faces important constrains between 5030 MHz and 5150 MHz where the Microwave Landing System (MLS) band is located. Furthermore, to make it even more difficult, also between 5000 MHz and 5010 MHz the downlink signals for a hypothetical Galileo C-band baseline signal would have to coexist with its uplink counterparts and ensure compatibility. Aiming at having band-limited signals from the very beginning is positive and actually desirable. This was indeed the main objective of the Galileo C-band signal design that this work will present: namely to find a signal plan based on Constant Envelope Continuous Phase Modulation (CECPM). This is proven to enable a better control of spectral emissions, and still to show performance figures equivalent to those of other well known signal modulations used today for satellite navigation. By doing so, similar navigation receivers and concepts which are common practice today could be reused. In addition, the scarce spectrum resources could be better managed. The CECPM signals present similar positioning performance figures as current modulations, but with a much superior spectrum confinement. This paper summarizes the main results on service and signal design that have been achieved in the C-band study that the authors are carrying out in the framework of the ESA Evolution Programme.
Published in:	Proceedings of the 21st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2008) September 16 - 19, 2008 Savannah International Convention Center Savannah, GA
Pages:	2515 - 2529
Cite this article:	Avila-Rodriguez, Jose-Angel, Wallner, Stefan, Won, Jong-Hoon, Eissfeller, Bernd, Schmitz-Peiffer, Andreas, Floch, Jean-Jacques, Colzi, Enrico, Gerner, Jean-Luc, "Study on a Galileo Signal and Service Plan for C-band," Proceedings of the 21st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2008), Savannah, GA, September 2008, pp. 2515-2529.
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