MRD and WAD Concepts Preliminary Assessment

J.R. Martín, P. Pablos, M. Romay, J. Cosmen, R.W. Okkes

Abstract:	The so called MRDSNS or Multi Reference Differential Satellite Navigation System also known as Multi Site DSNS is an alternative concept of Regional Area Differential (RAD) System. Together with WAD (Wide Area Differential), both augmentation systems provide high positioning accuracy and integrity within a large area such as a continent or ocean region. MRD is based on the user processing of the differential corrections generated by a network of stations spread over the coverage area. The most promising features are an easy transition from Regional Area Differential (RAD) to Local Area Differential (LAD) performance, which could solve the problem of the RAD/LAD integration, and the optimization of the navigation performance for the particular location of the user. The fact that no central processing is needed suggests also a potential robustness in comparison to centralized solutions. On the other hand, WAD is based on the processing in a master control center of the raw measurements taken by a network of stations. Corrections which are independent from the user location are then broadcast over the coverage area. This algorithm simplifies the user computational requirements as well as the data link between the user and ground segment, allowing the implementation of single GPS+WAD receivers. This paper is intended to provide a general overview of the MRD/WAD principles and to outline the major pros and cons. The paper presents a preliminary performance assessment based on the results obtained with real GPS low-noise (code-phase smoothed level) dual-frequency data emulating the ground stations network and users. Also the role of a RAD service is analyzed for the future European Navigation Satellite System (ENSS).
Published in:	Proceedings of the 10th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1997) September 16 - 19, 1997 Kansas City, MO
Pages:	1295 - 1303
Cite this article:	Martín, J.R., Pablos, P., Romay, M., Cosmen, J., Okkes, R.W., "MRD and WAD Concepts Preliminary Assessment," Proceedings of the 10th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1997), Kansas City, MO, September 1997, pp. 1295-1303.
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