Bringing the GNSSs on the Same Line in the GNSS Assistance Standards

Lauri Wirola and Jari Syrjarinne

Abstract:	The cellular networks, such as GSM (Global System for Mobile Communications) and UMTS (Universal Mobile Telecommunications Systems), have an in-built capability to assist integrated GPS receivers in cellular terminals. This assistance includes, among other things, the navigation model (orbit and clock parameters). In an assisted situation, the receiver does not need to obtain a copy of the navigation model from the satellites, but receives it over the cellular network. Until now there has been no need to assist any GNSS (Global Navigation Satellite System) other than GPS and, in fact, currently there is support only for L1 AGPS (Assisted GPS). Now, however, the introduction of new GNSSs, such as Galileo and GLONASS, demands updating the outdated AGPS-only solution. The main driver of the revision process is to add support for new GPS bands, new GNSSs, and to enhance the performance of positioning technologies in terms of accuracy, sensitivity and availability. This article discusses the various systems from the point of view of orbit and clock models. Ultimately, based on this discussion the future AGNSS assistance format for orbit and clock models is synthesized. The format is called the multi-mode navigation model and it has been approved by the 3GPP (3rd Generation Partnership Project) standardization body to be included in the GSM standard. The benefits of the new navigation model include that it can be used for all the current, known and future GNSSs. In addition, the multi-mode navigation model allows using non-native navigation models for GNSSs. This results in harmonized performance between the different GNSSs.
Published in:	Proceedings of the 63rd Annual Meeting of The Institute of Navigation (2007) April 23 - 25, 2007 Royal Sonesta Hotel Cambridge, MA
Pages:	242 - 252
Cite this article:	Wirola, Lauri, Syrjarinne, Jari, "Bringing the GNSSs on the Same Line in the GNSS Assistance Standards," Proceedings of the 63rd Annual Meeting of The Institute of Navigation (2007), Cambridge, MA, April 2007, pp. 242-252.
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