GNSS Local Integrity Augmentation … Future Standards for User Communication Links

Charles S. Dixon and Russell G. Morrison

Abstract:	The paper summarises the present standards for GNSS local augmentation communications links focusing on differential and integrity services for land mobile and maritime sectors. The limitations of the current standards are highlighted and proposals presented for future development. Developments include: the introduction of Galileo; specific provision for Integrity parameters; and provision for area coverage parameters. The paper presents the solution to each of the identified limitations in new proposals for communications link standards applicable for maritime and land mobile domains. These proposals include full message definitions designed to be compatible with RTCM protocols. One of the key needs with Integrity services is to minimise the time to notify users in the event of a malfunction in the satellite or augmentation system, usually called Time To Alert (TTA). The results from a detailed assessment of end-to-end TTA for different scenarios are presented. These take account of the specifics of the user communications link in terms of throughput, multiplex mechanism and message contention, and also include consideration of local system processing and internal communications links. The latter are particularly significant in the case of area coverage augmentation systems comprising multiple stations over baselines of many hundreds of kilometres. Communications links analysed were those commonly applicable for land mobile and maritime environments and include DAB, GSM-R, IALA Radiobeacons and AIS.
Published in:	Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005) September 13 - 16, 2005 Long Beach Convention Center Long Beach, CA
Pages:	311 - 321
Cite this article:	Dixon, Charles S., Morrison, Russell G., "GNSS Local Integrity Augmentation … Future Standards for User Communication Links," Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005), Long Beach, CA, September 2005, pp. 311-321.
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