ESA’s Multi-Constellation Regional System Land Users Test-Bed Integrity Algorithms Experimentation Results

E. Domínguez, J. Simón, M. Seetzen, Y. Zheng, E. Wittmann, D. Lekaim, M. Tossaint, M. Jeannot

Abstract:	The MLU Testbed (MLUTB) project is part of ESA’s GNSS Evolution programme (EGEP), whose aim is to study and develop technologies associated with Europe's two contributions to the field of Global Navigation Satellite Systems (GNSS): EGNOS and Galileo. The MLUTB is one of several test-beds intended to support European agencies (ESA and EC), users, and industry in evolving GNSS. The focus of this project is on multi-constellation land users (MLU), and in particular on two different services, the Proof of Position Service (POPS) and the Emergency Service (ES). This paper presents the experimentation and results obtained for the Proof of Position Service. The Proof of Position Service (POPS), an evolution of current positioning services provided by GNSS and SBAS systems for urban users, is for non-safety-of-life users, e.g. road users in urban or sub-urban environments, which still require some level of integrity, with relaxed integrity risk, relaxed time-to-alarm but possibly reduced horizontal alarm limits. POPS typically requires a robust and reliable positioning solution capable of delivering high integrity in urban conditions with restricted sky visibility and high levels of multipath. This performance must be achieved using consumer grade low-cost GNSS receivers to provide a scalable solution for millions of vehicles. The definitions and interpretation of integrity which are well established in safety critical applications, notably aviation, do not translate easily to this application domain. Error budgets and fault trees are dominated by local effects and equipment suppliers have tended to address these problems through hybridization with low cost sensors on the user terminal with the role of space and ground based augmentations to the core GNSS services remaining unclear. MLUTB analyses the benefits of a GNSS Integrity Channel (GIC) in urban environments and the impact of using more constellations (up to 4 constellations used to test the algorithms in the simulations). Besides comparing the performances provided by different state of the art integrity algorithms (three different families: snapshot, COTS automotive and GNSS&external sensor filtered), MLUTB also explores technologies that can provide greater assurance of user positions in a cost-effective manner, like the usage of a web-cam for Non Line of Sight (NLOS) detection. MLUTB POPS is divided in different stages, through them, MLUTB has enabled experimentation to focus R&D efforts on priorities deduced from experiments using real data: a) The theoretical review of Integrity algorithms (positioning algorithms also providing integrity): including a first assessment and comparison of existing integrity algorithms via Service Volume Simulator (SVS). This initial step provides a basis for the subsequent activities. b) End-to-End (ETE) simulation: ETE simulations performed with up to 4 constellations simulating the urban environment in 8 different locations to test the integrity algorithms selected in the previous phase. It provides a better assessment of the integrity algorithm performances and enables the fine tuning of the integrity algorithms, before conducting real life experimentations. c) The final Real Life Experimentation Campaigns (RLC): A set of Real Life experiments complete the study of POPS service. These experiments take place in different areas aiming to demonstrate the suitability of different integrity concepts. This includes the use of different: • External Sensor Components (ECS): odometer and Inertial Navigation Sensors (INS) • User algorithms • Constellations • Format of the GIC and the dissemination media of the GIC. • Pre-processing methods: Real-time camera exclusion or SNR/Elevation measurement down-weighting or exclusion There will be two different experimentation campaigns each using different constellations, environment and GIC dissemination paths: • Galileo Test Site: GATE serves as the POPS test environment for road test scenarios in sub-urban environments with increased levels of multipath and shadowing effects. MLUTB has provided to GATE GPS/Galileo integrity/augmentation data, incorporated into the I/NAV messages of E1 and E5b, which has been transmitted via the GATE GEO-like dissemination channel to the GATE user in the test bed. • Galileo IOV: Dynamic vehicle GPS only trials using Galileo IOV E6 as the GIC dissemination path. The raw measurements are recorded as received and analysed later offline by running the user algorithms on these measurements and retrieving the performance measurements. As already mentioned, besides testing the state of the art integrity algorithms coming from three different families: snapshot, COTS automotive (GNSS filtered) and GNSS&external sensor filtered, two methods for local effect mitigation are also implemented and analysed: Camera NLOS Detection and Elevation/SNR mask for measurement down-weighting or exclusion. The paper will present the results obtained in the different simulation and experimentation stages of the POPS service in the MLUTB project.
Published in:	Proceedings of the 26th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2013) September 16 - 20, 2013 Nashville Convention Center, Nashville, Tennessee Nashville, TN
Pages:	2672 - 2689
Cite this article:	Domínguez, E., Simón, J., Seetzen, M., Zheng, Y., Wittmann, E., Lekaim, D., Tossaint, M., Jeannot, M., "ESA’s Multi-Constellation Regional System Land Users Test-Bed Integrity Algorithms Experimentation Results," Proceedings of the 26th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2013), Nashville, TN, September 2013, pp. 2672-2689.
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