Concatenated Sequential Codes Performance Attributes and Applications for Galileo

Anthony R. Pratt, Matthew D. Powe, and John I.R. Owen

Abstract:	The basic principles of performance envelope of CSC codes were set out in a paper introduced at IoN GPS 2002 (ref 1) and subsequently developed in a number of presentations. This paper sets out the structure of the codes developed from these principles – so called concatenated sequential codes (CSC) – which are built from members of the same Gold family. Performance attributes in respect of auto-correlation and cross-correlation properties are shown for typical code construction methods. Some typical CSC codes are illustrated. Analysis using Möbius and Euler formulae demonstrates that for reasonable lengths of generator polynomial (for example 2 x 13 – CA code is drawn from 2 x 10) that there are sufficient codes for known and planned Satellite Positioning Systems to share common families of such codes. Such choices are of benefit to the user community through reductions in inter- and intra-system interference. A second aspect of the paper recognises the published attributes of the L5/Neumann-Hoffman codes and the Galileo Reference codes, which are similarly tiered. The basic cross-correlation features of these codes have been published for un-aided acquisition modes (ref 2) and show large sidelobe levels. Consequently, such codes may not be suitable for high signal dynamic range applications, such as indoor reception of satellite positioning signals. It is shown that CSC codes can overcome these objections and have greater flexibility but carry the penalty of an increase in search space during acquisition. A means to ameliorate this effect is proposed in which there is a structured sub-sequence forming an acquisition aid. Sparse code location techniques are used to control and reduce the effects of unwanted cross-correlations of the sub-sequences.
Published in:	Proceedings of the 2004 National Technical Meeting of The Institute of Navigation January 26 - 28, 2004 The Catamaran Resort Hotel San Diego, CA
Pages:	313 - 322
Cite this article:	Pratt, Anthony R., Powe, Matthew D., Owen, John I.R., "Concatenated Sequential Codes Performance Attributes and Applications for Galileo," Proceedings of the 2004 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2004, pp. 313-322.
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