数字副载波复用光纤通感融合系统干涉衰落抑制研究

摘要：针对数字副载波复用光纤通感融合（DSM-ISAC）系统中，相干探测型相位敏感光时域反射仪（Φ-OTDR）因干涉衰落导致传感性能劣化和可靠性下降的研究挑战，提出并实验验证了一种接收端多域集成数字信号处理衰落抑制方案。通过在接收端引入相位域的相移变换（PST）、频率域的脉冲内频分（IFD）和空间域的移动旋转矢量平均（MRVA），实现对干涉衰落的协同抑制。为了验证研究方案的有效性，搭建了DSM-ISAC实验平台，利用DSM信号的频谱灵活分配特点，优化子载波间保护间隔，将36 GBaud DP-16QAM DSM通信信号与线性调频（LFM）脉冲传感信号在同一波长信道中产生，并经过920 m标准单模光纤传输，完成DSM-ISAC系统干涉衰落抑制的实验验证。与传统干涉衰落抑制方案相比，所提出的PST-IFD-MRVA可显著抑制干涉衰落，提高强度信噪比近10 dB且增强应变灵敏度到9.09 pε/√Hz，成功解调出施加于光纤820 m处的10 kHz扰动信号。实验结果表明研究方案在提升DSM-ISAC系统的传感可靠性具有可行性。

关键词：光纤通感融合系统；数字副载波复用；相位敏感光时域反射仪；干涉衰落抑制

Abstract: As for fiber optics integrated sensing and communication systems enabled by digital subcarrier multiplexing (DSM-ISAC), the coherent-detection based phase-sensitive optical time-domain reflectometer (Φ-OTDR) suffers from impaired sensing performance and insufficient reliability due to the interference fading effect. A receiver-side multi-domain integrated fading suppression scheme is proposed. Its efficacy is experimentally validated. Without increasing hardware complexity, our proposed scheme sequentially applies phase shift transformation (PST) in the phase domain, inner-pulse frequency division (IFD) in the frequency domain, and moving rotation vector averaging (MRVA) in the spatial domain to achieve joint suppression of interference fading. To verify its performance, we establish a DSM-ISAC experimental platform. Leveraging the flexibility of spectral allocation in DSM signals, a 36 GBaud DP 16QAM DSM communication signal and a linear frequency modulated (LFM) pulse sensing signal are generated within the same wavelength channel and co-propagated over 920 m of standard single-mode fiber (SSMF), with an optimized protection interval bandwidth between the two central subcarriers. Experimental results indicate that, in comparison with conventional suppression schemes, the proposed PST-IFD-MRVA scheme significantly enhances fading suppression performance, achieving an improvement in signal-to-noise ratio of nearly 10 dB and a strain sensitivity of 9.09 pε/√Hz. Meanwhile, we successfully demodulate a 10 kHz vibration signal applied at the position of 820 m of SSMF. These findings validate the feasibility and promising potential of the proposed scheme in enhancing the sensing reliability of DSM-ISAC systems.

Keywords: integrated sensing and communication; digital subcarrier multiplexing; phase-sensitive optical time-domain reflectometer; interference fading suppression