A Core Constellation Based Multiple-GNSS Positioning and Integrity Monitoring Algorithm

Shaojun Feng, Shenghai Wang, Washington Ochieng

Abstract: With the modernization of existing Global Navigation Satellite Systems (GNSS) and the deployment new GNSS, it is expected that the full operation of multiple constellations is on the horizon. This will bring opportunities for user level positioning and integrity monitoring including more satellites, frequencies, message types, and better signal design and geometry. Considerable research has been undertaken on positioning and integrity monitoring using multiple GNSS. The existing methods do not have constrains on the use of any constellation. However, some countries have made their systems mandatory for some applications. This suggests that countries that own a GNSS are beginning to realise that critically national infrastructures using Position Navigation and Timing (PNT) services and a portion of the national economy associated with GNSS should not be over reliant on other countries. This paper addresses the technical issues of the existing methods and proposes a core constellation (as specified by individual countries) based multiple-GNSS positioning and integrity monitoring algorithm. A Receiver Autonomous Integrity Monitoring (RAIM) is embedded in the positioning algorithm with the core constellation. In order to benefit from the other constellations without compromise the performance of the core constellation, a real time validation algorithm for the measurements from the other constellations is developed using the solution from the core constellation. The measurements from other constellations are pre-processed with conventional methods including correcting for satellite clock, ionosphere effect and troposphere delay. The measurement residual errors relative to the position solution from the core constellation are assessed. Upon passing the validation process, the measurements from other constellations are integrated to benefit from the feature of multiple constellations and generate a better solution when core constellation suffers problems. The tests were carried out using the GPS and GLONASS data from the International GNSS Service (IGS) stations. GPS was used as a core constellation; while the ephemeris error and multiple failures in the other constellation are simulated. The test results show that the proposed methods can effectively identify potential issues in the non-core constellation and can benefit from the measurements validated by the core constellation. It has the potential to be used in applications where one constellation is mandated. The method can also be extended to multiple constellation cases.
Published in: Proceedings of the 27th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2014)
September 8 - 12, 2014
Tampa Convention Center
Tampa, Florida
Pages: 307 - 314
Cite this article: Feng, Shaojun, Wang, Shenghai, Ochieng, Washington, "A Core Constellation Based Multiple-GNSS Positioning and Integrity Monitoring Algorithm," Proceedings of the 27th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2014), Tampa, Florida, September 2014, pp. 307-314.
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