Spoofing Monitoring of GNSS Localization: A LDSASM Architecture for GNSS/Odometer-based Train Positioning

Abstract-The next generation railway train control system is designed with the utilization of the GNSS (Global Navigation Satellite System) localization to enhance the autonomy of the onboard equipment and effectively reduce the maintenance cost. In order to guarantee the safety and effectiveness of GNSS-based localization under complex GNSS observing conditions with potential GNSS spoofing attacks, the monitoring of GNSS spoofing is of great significance in an enhanced train localization system. In this paper, a spoofing monitoring solution is proposed within the GNSS positioning domain and measurement domain with assistance of the train odometry system, over conventional spoofing countermeasures through the specific signal processing operations. A GNSS/odometer integrated localization solution is employed, which only uses wheel pulse counting measurements from the odometer without relying on extra sensors. By utilizing both the odometer and trackmap data, a hierarchical LDSASM (Location Determination System Autonomous Spoofing Monitoring) architecture, covering both the odometer-channel initial detection stage and channel-wise spoofing detection stage, is established to identity the existence of the spoofing attack. Results from the GNSS spoofing injection tests demonstrate the effectiveness of the proposed solution under different satellite observing conditions. It is illustrated that the solution is simple for implementation and of great significance in the trustworthy train localization for novel GNSS-enabled railway systems.

I. Introduction

The development of Global Navigation Satellite System (GNSS), especially the BDS (BeiDou Navigation Satellite System) and Galileo, will greatly improve the availability of satellite navigation services in future railway systems. At the same time, the modernization of GPS is set to occur. The rapid development of GNSS constellations and new techniques makes it possible of playing an important role in the future railway signaling systems, by reducing the construction and maintenance cost of track-side infrastructure, enhancing the autonomy of train-bome equipment and increasing flexibility of the whole system. The latest stage of the European Train Control System (ETCS), ETCS level 3, is bringing new opportunities for GNSS-based train positioning with GNSS in hybridized solutions with assistant localization sensors (i.e.odometer, inertial sensors or radars) [1, 2], A series of R&D projects have been launched in Europe to investigate the applicability of the standardized satellite-based localization functionality, e.g. Next Generation Train Control (NGTC) [3] RHINOS [4] and Gate4Rail [5], Based on the development of high-speed railway in China, the framework of Chinese Train Control System (CTCS) also introduced advanced techniques into new CTCS schemes to realize next generation intelligent train control systems. Owing to the development of BDS, the satellite-based positioning is attracting more attention for the novel train control systems like CTCS-Level 4. It has been an inevitable solution to utilize the GPS/BDS dual mode GNSS positioning and a hybridized train positioning architecture in the new design [6],