Precise Time Transfer in a Mobile Radio Terminal

Peter J. Duffett-Smith and Paul Hansen

Abstract:	The degradation suffered by GPS installed in a mobile phone in shielded environments can be ameliorated to some extent by the use of network assistance (satellite information, GPS time information and coarse position) obtained from a fixed GPS terminal in the network, which can allow terminals to operate with GPS signals weaker by 20 dB or more. In this paper, we describe a new method of providing precise time aiding to mobile terminals used in un-synchronised communications networks such as GSM and W-CDMA ("3G") based on the Matrix positioning method by which the relative timings of network signals received by the handset are used to obtain both a terminal position and a network synchronisation map. This enables the terminal to carry precise GPS time information from open to shielded areas without requiring any GPS assistance from a networkbased server. Precise time aiding within a mobile communication terminal allows for GPS implementations of lower complexity and therefore of lower cost. This can be a crucial factor in mass-market take-up of satellite positioning technology in mobile phones.
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:	1101 - 1106
Cite this article:	Duffett-Smith, Peter J., Hansen, Paul, "Precise Time Transfer in a Mobile Radio Terminal," Proceedings of the 2005 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2005, pp. 1101-1106.
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