In the maritime domain, correction services such as DGPS (Differential GPS) are widely used to enhance satellite navigation accuracy for safe operation of vessels. Additionally, several studies have analyzed positioning performance by applying SBAS (Satellite-Based Augmentation Systems) to maritime applications. However, DGPS requires additional equipment such as beacons capable of receiving medium-frequency signals, and SBAS has been reported to fall short of meeting the accuracy requirements specified by the IMO (International Maritime Organization).
PPP-RTK (Precise Point Positioning–Real-Time Kinematic) is a precise positioning technique that provides satellite orbit and clock information, signal biases, and atmospheric delay corrections through SSR (State Space Representation). A key advantage of PPP-RTK is that correction information can be delivered via existing LTE or satellite communication networks.
According to statistics from the MOF (Ministry of Oceans and Fisheries) of Republic of Korea, approximately 80% of the 63,731 registered fishing vessels are small vessels under five tons. Therefore, this study focuses on small maritime vessels equipped with low-cost single-frequency GNSS receivers, which represent the majority of maritime navigation users. PPP-RTK correction information was generated using data from nationwide GNSS CORSs (Continuously Operating Reference Stations) in the Republic of Korea, and the resulting positioning accuracy for single-frequency users was comparatively analyzed.
The results confirmed the feasibility of using the PPP-RTK-based positioning method as an alternative to existing correction services, including DGNSS and SBAS.

Performance Evaluation of a Regional GPS+Galileo PPP-RTK Service for Cosatal Maritime Navigation in Korea

The POINT service was initially developed to provide centimeter-level GNSS augmentation across the Korean region, and its core PPP-RTK functionality has already been validated through land-based performance assessments. To support this service, a nationwide infrastructure was established, consisting of reference stations for correction generation, monitoring stations for quality assessment, and evaluation-monitoring stations dedicated to integrity verification. While the initial system was implemented using GPS-only observations, subsequent analyses revealed performance degradation in terms of positioning accuracy and convergence time at the outer edges of the service coverage, particularly in maritime and coastal environments.

To address these limitations, Galileo was incorporated into the PPP-RTK service architecture to enhance satellite availability, geometry, and measurement redundancy. This study presents the development and performance evaluation of a regional GPS+Galileo L1/L2 PPP-RTK system designed to provide high-accuracy positioning services within 100 km of the Korean coastline. Following the completion of land-based experiments, sea trials are being conducted using a vessel navigating along representative coastal routes to assess system performance under realistic maritime conditions.

During these experiments, the positioning accuracy, convergence behavior, and operational robustness of the proposed PPP-RTK solution are evaluated and compared with conventional PPP and RTK solutions. The analysis focuses on performance under dynamic conditions such as multipath, intermittent signal blockage, and temporary satellite visibility degradation. Through comparative evaluation and in-depth performance analysis, this study aims to provide practical insights into the benefits and limitations of multi-constellation PPP-RTK for coastal maritime navigation.

The AVIS project investigates how EGNSS and Copernicus services can support the development of safe automated navigation for inland waterway vessels. Inland waterways navigation conditions and evolving environments present a real challenging paradigm from the design and assurance perspective for automated applications. This paper presents the safety development in AVIS.
The safety process begins with the definition of a Safe IWW Navigation Concept and identifying all the factors that may jeopardize the automated navigation, named "Navigation factors". A comprehensive classification of navigation factors, both internal (vessel characteristics, navigation and control systems) and external (waterway geometry, authority services, weather, water conditions, dynamic obstacles), supports a systematic identification of hazards. The resulting Hazard Analysis covers general IWW navigation hazards as well as EGNSS- and Copernicus-specific threats, evaluating their effects on integrity, continuity and accuracy. This analysis allow to identify a Safety Architecture and a set of Safety recommendations.
The project digs into the Volumetric Navigation concept, where the vessel is surrounded by a three-dimensional Envelope Protection Level (EPL), that surrounds the vessel bounding positional uncertainty, with a defined confidence level in accordance with the Integrity requirements of the application. Navigation is permissible only when the EPL remains within an Alert Limit consistent with the expected risk levels and automation level. The proposed IWW navigation concept provides a quantitative mechanism to manage uncertainty from GNSS, vessel dynamics, environmental effects, and waterway variability. It also enables the system to dynamically regulate the Automation Level based on real-time risk, ensuring that safety responsibilities are clearly distributed between the human operator and the automated system.
Major outcomes of the work are a preliminary Safety Architecture; Waterway Suitability Criteria, defining minimum fairway width based on PL magnitude, vessel dimensions, hydrodynamic effects and maneuvering margins; and the identification of current major technological limitations regarding the safe automated navigation.

Finally, the study presents a preliminary Safety Case that consolidates these results and shows that, while EGNSS and Copernicus significantly contribute to enhancing situational awareness, and potentially may support safe navigation in the future, currently they are not sufficient on their own to ensure fully automated inland navigation. It is required additional technological enablers and a mature regulatory framework.

The evolution of transportation systems toward greater safety, sustainability, and interoperability is reshaping positioning technologies for rail and maritime domains. This paper presents a resilient and autonomous positioning framework that integrates GNSS, IMU, LiDAR, and video odometry for high-integrity, continuous localization in diverse conditions.

The European Rail Traffic Management System (ERTMS) is transforming with the introduction of the Absolute Safe Train Positioning System (ASTP). ASTP reduces reliance on GNSS alone and enhances PVT solutions. It supports various control, automation, and management functions, including train protection, operations, traffic management, and passenger information systems.

The overarching goal is to increase train capacity and safety while minimizing infrastructure costs by reducing the need for trackside assets and enabling migration from legacy balise-odometry systems to open, multi-technology interfaces. In parallel, the maritime sector is embracing digitalization for autonomous navigation, eco-sustainable port operations, and enhanced safety. In this context, Radiolabs roadmap is based on complementary cross-sector projects involving potential users. The goal is to be complying with Safety and Validation standards plus Resiliency and Autonomy attributes that are gaining importance.

The convergence of rail and maritime positioning technologies is enabled by shared requirements for high accuracy, integrity, and resiliency. Both sectors benefit from multi-constellation GNSS (Galileo, EGNOS), RTK/PPP corrections, and advanced sensor fusion, but face unique challenges: rail must contend with tunnels, urban canyons, and cyber threats, while maritime environments introduce multipath effects, dynamic vessel motion, and harsh weather. Radiolabs’ research demonstrates that leveraging on the safety primacy of rail, technical synergies, and production scale across domains to reduce the costs is crucial to accelerate the adoption of these new technologies.

The paper will present the outcomes of the Radiolabs projects that demonstrate a novel direction in the importance of aligning design and validation strategies for a multi-layered generic architecture.
• Navigation Layer: Tightly couples GNSS and IMU, exploiting track constraints for dead reckoning in GNSS-denied areas and correcting long-term drift with GNSS updates. Adaptive noise models and multi-hypothesis solution separation enhance robustness against multipath and dynamic conditions.
• Perception & Odometry Layer: Fuses LiDAR-inertial and visual-inertial odometry to estimate relative motion, leveraging known rail geometry and odometer data to minimize drift. A novel algorithm performs Iterative Closest Point (ICP) registration in the polar coordinate domain for curved tracks, simplifying point cloud processing and improving accuracy.
• Global Estimation & Integrity Layer: Outputs train dynamics (position, velocity, attitude) with associated covariance and integrity metrics. Cross-sensor consistency checks, fault detection and exclusion (FDE), and integrity risk propagation ensure safety targets are met, even in the presence of sensor faults or cyberattacks.

Our paper will demonstrate that resilient, autonomous and eco-sustainable positioning is achievable through tightly integrated, multi-sensor architectures. The added value is the groundwork for cross-domain synergies between rail and maritime and other transport sectors. This approach not only advances the state of the art for rail and maritime applications but is a competitive differentiator for the digitalization of transport means with GNSS technologies in Europe and beyond.