Vibration Localization under Unidirectional Single-Channel Transmission Conditions in the DSCM Systems Based on Non-Reciprocity

This paper proposes a vibration localization method for digital subcarrier multiplexing (DSCM) systems under unidirectional single-channel transmission conditions. By employing frequency-domain pilot tones (FPTs), vibration-induced phase perturbations are extracted, and their non-reciprocity with link dispersion is utilized to estimate vibration positions. Compared to conventional bidirectional or multiwavelength schemes, the proposed approach requires only a single coherent receiver, enabling joint communication and distributed vibration sensing without stringent synchronization or ultra-wideband requirements. Numerical simulations validate the method's performance for vibration frequencies ranging from 500 kHz to 1000 kHz over a 40 km link, demonstrating localization with a standard deviation below 500 meters. Results indicate that higher vibration frequencies and amplitudes improve localization accuracy due to pronounced non-reciprocity. This work offers a rare example of forward-phase-based vibration localization tailored to single-channel unidirectional transmission, providing a flexible and practical solution for integrated sensing and communication in optical networks.