IM-TLP: An Integrity Monitoring Algorithm for Two-Stage LCX Positioning Systems

Highly accurate train positioning and safe train operations are essential parts of intelligent transportation systems. Tunnels are frequently encountered in subways and mountainous regions and pose unique challenges due to the unavailability of Global Navigation Satellite System (GNSS). The Leaky CoaXial (LCX) Cable, already a part of the communication infrastructure, serve as antenna within tunnels due to its numerous advantages. The application of LCX positioning shows significant potential for advancing rail technology in the forthcoming BSG (beyond-SG) and 6G eras. To ensure highly accurate and safe train operations, this paper builds upon our previous work on LCX positioning methodology and proposes an integrity monitoring algorithm called 1M - TLP (Integrity Monitoring for Two-stage LCX Positioning) for the two-stage LCX positioning system with redundant infrastructure. A multi-LCX system is introduced and the fault detection and fault exclusion method for the multi-LCX positioning system is proposed. Then, to assess the integrity risks of the multi-LCX positioning system, the Along Track Protection Level (ATPL) for the system is defined. Simulation results show that the proposed 1M - TLP algorithm is capable of detecting random system faults, improving the overall system positioning accuracy and ensuring the safety of train operations.