Multiple Constellation Navigation Performance Using Long-Term Ephemeris Extension with Backward Error Representation

Yihe Li, Zhixi Nie, Shaohua Chen, Yang Gao

Abstract:	Long-term ephemeris extension is needed in challenging environments in order to reduce the Time-To-First-Fixed (TTFF). It makes quick position fix possible for mobile devices while they are still acquiring the broadcast ephemeris. Based on the experiment results described in this paper, the median User Range Error (URE) for the extended ephemeris after 3 and 7 days are 2.14m and 7.36m, respectively. Both of the multi-constellation extended ephemeris and its accuracy represented with backward errors are used for urban navigation. Simulated signal obstruction experiments are also conducted to assess the position fix accuracy, availability and reliability based on different mean square positional error (MSPE) thresholds, prediction durations and obstruction scenarios. The results have demonstrated superior performance for multiple constellation navigation system with backward error representation method compared to the GPS only system without backward error representation. With the aid of multiple constellation, the obtained average navigation availability and reliability improve from 67.7% to 93.4% while the reliability also improve from 88.1% to 89.5% using a user-defined MSPE of 15m after 3 days’ prediction. Both of the average availability and reliability can further increase to 97.1% and 94.8% after applying the revised strategy considering the ephemeris extension errors with backward representation method.
Published in:	Proceedings of the ION 2015 Pacific PNT Meeting April 20 - 23, 2015 Marriott Waikiki Beach Resort & Spa Honolulu, Hawaii
Pages:	117 - 130
Cite this article:	Li, Yihe, Nie, Zhixi, Chen, Shaohua, Gao, Yang, "Multiple Constellation Navigation Performance Using Long-Term Ephemeris Extension with Backward Error Representation," Proceedings of the ION 2015 Pacific PNT Meeting, Honolulu, Hawaii, April 2015, pp. 117-130.
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