Performance of a Collaborative Peer PPP-RTK with Ionospheric and Tropospheric Estimation Exchanges for Short-range Networks of Selfdriving Users

Roberto Capua and Kyle O’Keefe

Abstract:	The objective of this paper is to analyze the performance of a high accuracy GNSS positioning system based on a dense network of peer users, exchanging precise Ionospheric and Tropospheric estimates, in a PPP-RTK operational framework. PPP-AR technique, out of precise satellite orbit and clocks, needs satellite biases estimates provided to the receiver by external sources. It usually requires a long convergence time for fixing ambiguities. The present work analyses the performance of a network of closely spaced (on the order of a few km or less) user receivers using standalone PPP-RTK with the addition of sharing precise STEC and ZTD estimates through a Peer PPP-RTK approach. These are applied by Peer as constraints for faster convergence to sub-decimeter accuracies. Peer solutions are processed through a decentralized Federated Kalman Filter approach, where all the peers are considered as independent local filters, deriving autonomously their own federated solution and integrating closer peer ionospheric and tropospheric estimations. The developed processing engine is tested in simulation and using real data from a network of permanent reference stations treated and densified through VRS, representing kinematic users. A performance analysis to assess the impact of network receiver spacing with different scales of ad-hoc networks is carried out, in order to simulate possible application scenarios (e.g. car information sharing and crowdsourcing in a Collaborative – Intelligent Transportation System perspective). For evaluating the performance of a dense network of peers in a city, a Monte Carlo simulation over 500 randomly distributed network is carried out and convergence time statistics derived through Minimum Spanning Tree analysis.
Published in:	Proceedings of the 34th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2021) September 20 - 24, 2021 Union Station Hotel St. Louis, Missouri
Pages:	753 - 771
Cite this article:	Capua, Roberto, O’Keefe, Kyle, "Performance of a Collaborative Peer PPP-RTK with Ionospheric and Tropospheric Estimation Exchanges for Short-range Networks of Selfdriving Users," Proceedings of the 34th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2021), St. Louis, Missouri, September 2021, pp. 753-771. https://doi.org/10.33012/2021.17915
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