Integrated Communication and Enhanced Forward Phase-Based Sensing Based on Frequency-Domain Pilot Tones in DSCM Systems Using 100 kHz ECLs

In this paper, integrated scheme of enhanced vibration-sensing and digital subcarrier multiplexing (DSCM) communication based on frequency-domain pilot tones (FPTs) is proposed and demonstrated experimentally. In the scheme, FPTs are employed for multiple receiver digital signal processing (DSP) modules including frequency offset estimation (FOE), carrier phase estimation (CPE) and polarization demultiplexing. Meanwhile, with the recovered phase after CPE, the vibration-induced phase is extracted for sensing with band-pass filter within a frequency range of 7 kHz to 50 kHz. Thanks to two FPTs, dynamic FOE performance is enhanced under the frequency drift of 100 kHz ECLs compared to the conventional FOE methods, such as Max-Fast Fourier Transform (Max-FFT) and Viterbi-Viterbi (VV) algorithm. This enhancement can effectively suppress the background noise of the recovered phase after CPE, which inherently can subsequently improve the vibration sensing ability at a low frequency. In the experiment, sensing signal-to-noise ratio (SSNR) at 10 kHz is improved by 10 dB with the aid of FPTs. As a result, the vibration of frequency down to 10 kHz is successfully detected based on forward phase-based sensing in integrated DSCM communication system using commercial 100 kHz ECLs. The proposed integrated solution is compatible with the existing optical networks employing commercial ECLs to support intelligent operation and maintenance.

I. Introduction

In Recent years, integrated fiber optical communication and sensing technology has received extensive attention from academic research and industry. By utilizing the existing fiber optic cables effectively, efficient monitoring of external disturbances [1], environmental changes [2], [3] and natural disasters [4], [5] has been investigated. Meanwhile, along with the development of AI big models, the reliability of data centre optical interconnections is more important. The intelligent operation and maintenance of fiber optic cables has more significant significance, such as co-cable identification [6], [7], [8], [9]. Integrated communication and sensing scheme can enhance the capability and efficiency of intelligent operation and maintenance of fiber optic cables.