Terrestrial Positioning Service

J. A. del Peral-Rosado, A. Yildirim, Susanne Schlötzer, P. Nolle, Sara M. Razavi, Sagar Parsawa, Rakesh Mundlamuri, Florian Kaltenberger, Niilo Sirola, Stefano Garlaschi, Luca Canzian, J. Talvitie, Ivan Lapin, Detlef Flachs

This work presents field results of a dedicated fifth generation (5G) network with ground and aerial base stations (BSs) deployed at Airbus premises for positioning purposes. This field campaign is part of a first-of-a-kind testbed for hybrid Global Navigation Satellite Systems (GNSS), 5G new radio (NR) and sensor positioning, called Hybrid Overlay Positioning with 5G and GNSS (HOP-5G) testbed. The dedicated 5G network exploits the standard positioning reference signal (PRS) to support positioning capabilities within the 5G NR downlink transmissions. The goal of this dedicated 5G network is to enhance the accuracy and reliability of hybrid positioning services based on the fusion of GNSS, 5G NR and sensors. This hybridization is especially relevant in the case of a service interruption by any of those technologies, being GNSS the most reliable but not exempt of vulnerabilities. To the best of authors’ knowledge, this paper presents the first field results of a 5G network with mixed setup of BSs deployed on ground and at unmanned aerial vehicle (UAV) payloads dedicated for positioning purposes. This field campaign is performed at a heliport within Airbus premises in Ottobrunn (Germany), as representative use case. The paper assesses the pseudorange noise of the real-time 5G NR measurements from three ground and one aerial BSs. These first field trials results achieve a pseudorange noise below 80cm in the 95% of cases, thanks to the 80-MHz PRS bandwidth, demonstrating the feasibility to deploy a dedicated 5G network of ground and flying BSs for high-accuracy positioning. Future work focuses on the assessment of sub-meter hybrid positioning accuracies.

S. Meiyappan, A. Raghupathy, Ganesh Pattabiraman

Mariano Conti, Christian Circi

A lunar global positioning–navigation–timing (PNT) and communication system can greatly support the exploration and exploitation of the Moon. In this study, the application of the stable orbits of the L1 and L2 halo families and the unstable orbits of L3 in the Earth–Moon system is analyzed, and a design is proposed. L3 halo orbits are considered for a continuous line-of-sight satellite infrastructure for the Earth–Moon communication, thereby providing an opportunity for ground stations on the Earth to participate in lunar missions even if they do not directly see the Moon. In this study, a constellation of 26 satellites distributed over a lunar segment, made of four halo orbits of L1 and L2, and a terrestrial segment, made of two halo orbits of L3, is designed; this constellation facilitates global and continuative Earth–Moon communication and provides accurate and continuous lunar PNT service. According to a station-keeping analysis in the framework of the elliptical restricted three-body problem, the maintenance cost for approximately 60 d was 0.76 m/s for the lunar segment and 0.02 m/s for the terrestrial segment.

Alejandro González-Garrido, J. Querol, S. Chatzinotas

The Fifth Generation (5G) New Radio offers a new Positioning, Navigation, and Timing (PNT) service with larger signal bandwidth and higher frequency carriers than previous generations, delivering more accurate measurements. This allows other vertical industries to benefit from this feature, opening up new possibilities. Furthermore, the 5G network includes Non-Terrestrial Network (NTN) elements such as Unmanned Aerial Vehicle (UAV), High-Altitude Platform Systems (HAPS), and satellites, which are gaining significant attention from the industry to allow for global communication. The future 6G aims to create a single network entity with multiple connectivity layers for all devices in all scenarios. Therefore, when combining both aspects of the 5G networks, the PNT service, and the NTN, there are several benefits such as: an independent and complete communication and navigation system under a single network, higher accuracy on the PNT solution than previous generation, global coverage for join navigation and communication, higher resilience on the positioning estimation, or new services offered. However, this is not free of challenges, as it is expected to achieve an accuracy, at least, similar to Global Navigation Satellite System (GNSS). One of the challenges is the multiplexing of the data and positioning service using a single infrastructure such a satellite. This paper has the purpose of analysing the effect in the accuracy of a delay estimator when a satellite constellation send a Positioning Reference Signal (PRS). Assuming that all satellites share the same frequency carrier and are synchronised between them. This 5G PRS main characteristic is its flexibility in terms of resource usage such as bandwidth, resource element density, symbols periodicity, a muting scheme, etc. This flexibility will be exploited in this paper to get a UE capable to estimate the Downlink Observed Time Difference of Arrival (DL-OTDoA) of the signal. Two challenges are present in this work, both are related to the characteristics of the RF channel between the Next Generation Base Station (gNB) and the User Equipment (UE): the first one is how the UE will cope with the high Doppler shift due to the high speed of the Low Earth Orbit (LEO) gNB increasing the Inter-Carrier Interference (ICI); and the second challenge is the effect of variable delay between OFDM symbols in the same slot and transmitter, increasing the effect of Intersymbol Interference (ISI). The contribution of the authors on this paper is the analysis of different PRS configuration that keeps a low interfere level between the moving gNBs. The result of this research highlight the impact that the length in number of subcarriers and number of OFDM symbol has in the accuracy of the delay estimation. It shows a trade-off in the constellation design, as a higher number of satellites in visibility also increase the ICI and ISI.

Hamed Talebian, Nazrul Nazeer, Darius Chmieliauskas, Jakub Nikonowicz, Mehdi Haghshenas, Lukasz Matuszewski, Mairo Leier, Aamir Mahmood

This paper presents a terrestrial localization system based on 5G infrastructure as a viable alternative to GNSS, particularly in scenarios where GNSS signals are obstructed or unavailable. It discusses network planning aimed at enabling positioning as a primary service, in contrast to the traditional focus on communication services in terrestrial networks. Building on a network infrastructure optimized for positioning, the paper proposes a system that leverages carrier phase (CP) ranging in combination with trilateration to localize the user within the network when at least three base stations (BSs) provide line-of-sight (LOS) conditions. Achieving accurate CP-based positioning requires addressing three key challenges: integer ambiguity resolution, LOS/NLOS link identification, and localization under obstructed LOS conditions. To this end, the system employs a multi-carrier CP approach, which eliminates the need for explicit integer ambiguity estimation. Additionally, a deep learning model is developed to identify NLOS links and exclude them from the trilateration process. In cases where LOS is obstructed and CP ranging becomes unreliable, the system incorporates an error-state extended Kalman filter to fuse complementary data from other sensors, such as inertial measurement units (IMUs) and cameras. This hybrid approach enables robust tracking of moving users across diverse channel conditions. The performance of the proposed terrestrial positioning system is evaluated using the real-world KITTI dataset, featuring a moving vehicle in an urban environment. Simulation results show that the system can achieve a positioning error of less than 5 meters in the KITTI urban scenario--comparable to that of public commercial GNSS services--highlighting its potential as a resilient and accurate solution for GNSS-denied environments.