Assisted GNSS - Performance Results of Multiplexed Measurements, Limited Bandwidth, and a Vectorized Implementation

T. Chu, D. Akos

Abstract:	Rather than improving sensitivity by further leveraging long integration in harsh urban areas, this paper tests the positioning performance by combining both GPS and GLONASS measurements. Aiming at building the lowest possible cost, best urban performing assisted GNSS receiver architecture, five assisted ""push-to-fix"" GPS/GLONASS techniques are implemented and compared. They are: (a) traditional A-GPS; (b) A-GPS/GLONASS (A-GNSS); (c) A-GNSS with multiplexed measurements; (d) A-GNSS with limited GLONASS bandwidth; (e) A-GNSS leveraging a vectorized approach (V-GNSS). All these techniques are implemented and tested with a live dataset collected in downtown Denver, CO, USA. In addition to these tests, several COTS OEM receivers are also included for comparison. To evaluate the performance of all these architectures, a truth reference is utilized to assess/compare the horizontal positioning error throughout the test period. The experimental results reveal that in challenging urban environment, ""more measurements adoption"" significantly benefits the assisted solution, even if frequency band has been limited. Multiplexed GNSS provides an economical approach to replace the parallel front end design for mass market applications. The vectorized technique can improve the probability of acquisition/push-to-fix, while decreasing the required sensitivity even with a coarse search strategy around the possible user positions. Each satellite contributes differently to the combined sensitivity loss according to dissimilar elevation angles. A simulation test is conducted to illustrate the sensitivity loss at several observation sites at different latitudes throughout the globe. The results indicate negligible difference of combined correlation losses at these sites.
Published in:	Proceedings of the 2011 International Technical Meeting of The Institute of Navigation January 24 - 26, 2011 Catamaran Resort Hotel San Diego, CA
Pages:	1007 - 1018
Cite this article:	Chu, T., Akos, D., "Assisted GNSS - Performance Results of Multiplexed Measurements, Limited Bandwidth, and a Vectorized Implementation," Proceedings of the 2011 International Technical Meeting of The Institute of Navigation, San Diego, CA, January 2011, pp. 1007-1018.
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