Hybridizing GNSS with Sensors and Terrestrial Technologies for Positioning in 5G

G. Cueto-Felgueroso, F. Grec, J.A. del Peral-Rosado, G. Seco-Granados, C. Gentner, E. Staudinger, D. Bartlett, E. Serna, M. Azaola, E. Domínguez, A. Fernández, F. Blázquez, F. Mata, R. Prieto-Cerdeira, L. Ries

Abstract:	Fifth generation mobile network (5G), the newest mobile wireless standard to be set, has generated great expectations to be a revolution in wireless market combining different wireless technologies (4G LTE, WiFi and 5G newly defined air interfaces, a.k.a. 5G NR – New Radio) to cover new use cases and exploiting new frequency bands. 5G will address many new types of users, ranging from low data-rate for narrowband Internet of Things (IoT) to ultrafast enhanced broadband or boosting industrial automation, connected vehicles and autonomous driving, and it will be exploiting technologies such as millimeter waves, small cells, massive Multi Input Multiple Output (MIMO) among others. For many of those new users, positioning and timing is a key function and therefore positioning aspects are extremely important, both provided via GNSS, the terrestrial communication infrastructure or eventually and hybridization of technologies. From 1G to current 4G, there were advances on cellular network-based localization to support emergency and location-based services such as Enhanced 911 (E911). The 3rd-Generation Partnership Project (3GPP), dealing with related communication standards, included location methods and protocols in the 2G, 3G and 4G cellular standards. Indeed, the 4G standard even defined dedicated positioning resources, such as the positioning reference signal (PRS) and the Long-Term Evolution (LTE) positioning Protocol (LPP). However, up to now most of cellular networks have only provided basic localization methods such as enhanced cell ID or assistance data for GNSS. This is because localization has been considered an optional feature in cellular networks (apart from some commitment to regulatory requirements). A new perspective is envisaged in latest releases of 4G LTE and 5G in the future, due to the introduction of high-accuracy positioning services. As such, 3GPP is moving towards including localization aspects for a wide range of markets including commercial use cases. This effort has been translated in specific 3GPP activities aiming at providing high accuracy GNSS for LTE and NR technologies and also designing Radio Access Technology (RAT)-dependent technologies to meet more stringent targets. For high-accuracy positioning, for instance to support of autonomous driving or industrial automation, the integration of GNSS (augmented with precise or differential corrections), terrestrial (RAT-dependent) technologies and complementary sensors is expected to play a key role on 5G localization. The European Space Agency (ESA) has taken the initiative in 2016 to strongly contribute in 3GPP and other standardization bodies to assess the 5G positioning user needs and possible technological solutions, including the role of GNSS and hybrid solutions [1]. This initiative has strongly contributed to the identification of 5G use cases and performance targets and grouping them in positioning service levels as part of the 5G_HYPOS 3GPP Study Item [2]. It has also supported the adoption of dissemination of high-accuracy positioning corrections (RTK, PPP and in the future PPP-RTK) for multi-constellation GNSS as part of the LPP protocol [3-5]. As part of this initiative, the GINTO5G (GNSS Integration into 5G wireless Networks) project, financed by the ESA under the European GNSS Evolution Programme (EGEP ID107) was launched. Its goal is to support the 3GPP standardisation activities by carrying out state-of-art experimental and simulation results, as well as assessing innovative techniques. The project is being developed by a consortium led by GMV with participation from DLR, UAB, u-Blox, Telefónica I+D among others. The key tasks performed within GINTO5G project include: • Performing field-test experimentation campaigns with state-of-art measurement platforms aiming at being representative of positioning technologies in 5G terminals (including GNSS, RAT-dependent and other technologies) for each of the selected use cases and related technical requirements. • Developing a simulation platform, and perform simulations, for the overall assessment of achievable performances, including the assessment of apportionment between different techniques (GNSS, RAT-dependent and sensors) in hybrid solutions and the comparison of different technologies. • Support ESA on the contributions to 5G standardization groups in aspects related to positioning, in particular 3GPP. The project focuses on three main use cases: Low Energy IoT users/applications, autonomous driving and low altitude UAVs. These use cases are driven by different levels of positioning capabilities and are representative of the main verticals envisaged for 5G with new localization targets. The project considers experimentation campaigns with a wide range of candidate positioning technologies: multi-constellation GNSS including different GNSS receiver grades and differential techniques (RTK, NRTK, PPP, PPP-RTK), additional sensors (different grades of Inertial Measurement Units) and wireless terrestrial network solutions (e.g. LTE and mm-Wave). In addition, another output of the project is the development of the PoPeCoT (Positioning Performance and Coverage Tool), a rich system simulator including GNSS, 3GPP (4G/5G) and hybrid technologies for positioning, which allows to assess the performance mainly in terms of positioning and energy consumption for the different use cases and under different environments. The simulator relies on realistic models derived from the results of the field campaign. The PoPeCoT simulator is based on three main modules, one for GNSS simulation, another one for 3GPP simulation and a third one called Navigation Service Volume Simulator (NSVS) in charge of hybridizing technologies and computing the final navigation solution and performance thereof. The PoPeCoT simulator will be fed from the error models and conclusions extracted from the results of the experimentation field tests carried out in the frame of the project. The NSVS will generate a hybrid GNSS/3GPP solution based on a loose coupling approach; GNSS PVT will be hybridized with the 3GPP raw measurements. Inertial sensors will be part of the GNSS PVT. This approach has been deemed optimal in order to simulate high performance state-of-the-art commercials solutions (e.g. PPP-RTK, PPP+IMU). For some use cases (e.g. LE-IoT), a tight coupling approach might be used as long as it is not intended to represent highly sophisticated navigation algorithms as those mentioned earlier. The NSVS will compute navigation errors (based on the knowledge of the true position/trajectory), derive the performance figures and display them on the 2D map when applicable. The PoPeCoT simulator will be able to perform both trajectory and coverage simulations for the relevant figures of merit. The paper and presentation will provide a summary of the main outcomes of the activities developed in the frame of the project, and in particular to present: • the results and conclusions from field-tests; • the campaign data analysis extracted to configure the PoPeCoT error models; • the PoPeCoT simulation platform description; • the relevant outcomes of the different simulation test cases targeting the project use cases. References: [1] Prieto-Cerdeira R., Ries L., Grec F., Cioni S., de Gaudenzi R., Manteiga-Bautista M., “The role of GNSS in 5G Wireless Networks”, NAVITEC 2018, December 2018. [2] 3GPP SA, “Study on Positioning Use Cases (FS_5G_ HYPOS)”, 3GPP SA#76, SP-170589. http://www.3gpp.org/ftp/tsg_sa/TSG_SA/TSGS_76/Docs/SP-170589.zip [3] 3GPP TS 36.305, "Stage 2 functional specification of User Equipment (UE) positioning in LTE" [4] 3GPP TS 36.355, "Evolved Universal Terrestrial Radio Access (E-UTRA); LTE Positioning Protocol (LPP)". [5] 3GPP TS 38.805, “Stage 2 functional specification of User Equipment (UE) positioning in NR”
Published in:	Proceedings of the 32nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2019) September 16 - 20, 2019 Hyatt Regency Miami Miami, Florida
Pages:	1295 - 1334
Cite this article:	Cueto-Felgueroso, G., Grec, F., del Peral-Rosado, J.A., Seco-Granados, G., Gentner, C., Staudinger, E., Bartlett, D., Serna, E., Azaola, M., Domínguez, E., Fernández, A., Blázquez, F., Mata, F., Prieto-Cerdeira, R., Ries, L., "Hybridizing GNSS with Sensors and Terrestrial Technologies for Positioning in 5G," Proceedings of the 32nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2019), Miami, Florida, September 2019, pp. 1295-1334. https://doi.org/10.33012/2019.17131
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