Subcarrier Tracking Performances of BOC, ALTBOC and MBOC Signals

A. de Latour, T. Grelier, G. Artaud, L. Ries, J-L. Issler, and V. Heiries

Abstract:	Future Galileo signals will use three modulations (BOC, AltBOC and CBOC) with a subcarrier which modulates the spreading code. The Galileo Public Regulated Service (PRS) will use two BOC modulations transmitted in frequency-bands E1 (1575.42 MHz) and E6 (1278.75 MHz). The Open Service (OS) and the Safety of Life (SoL) will consist in the CBOC modulation in E1 and in the AltBOC modulation in E5 (1191.8 MHz). BOC tracking architectures which have been widely studied rely on well-known tracking techniques developed for BPSK modulations with prompt, early and late replicas. In this paper we present a different approach which consists in tracking the subcarrier phase as it is done for the carrier. In this new type of architecture the replicas are built with subcarriers in phase and in quadrature. The presented subcarrier processing techniques seem efficient to track BOC, CBOC and AltBOC modulations especially when the subcarrier rate is high compare to the code rate. A new simplified tracking architecture can be used to decrease the number of operations and the consumption thanks to subcarrier phase factorization. The subcarrier processing shows a better code tracking threshold than the well-known dotproduct processing. For the PRS and the E5 OS, the multi-path error envelope is similar to the Dot-Product envelope. For E1 OS the multipath error envelope is better with a Dot-Product processing.
Published in:	Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007) September 25 - 28, 2007 Fort Worth Convention Center Fort Worth, TX
Pages:	769 - 781
Cite this article:	de Latour, A., Grelier, T., Artaud, G., Ries, L., Issler, J-L., Heiries, V., "Subcarrier Tracking Performances of BOC, ALTBOC and MBOC Signals," Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007), Fort Worth, TX, September 2007, pp. 769-781.
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