Advanced Integration of Sensing and Communication With High DSP Compatibility for SMART Network

Concept of the Scientific Monitoring and Reliable Telecommunications (SMART) network involves utilizing submarine communication cables to monitor the undersea environment. Traditionally, this integrated sensing and communication (ISAC) application has relied on separate wavelength bands for sensing information switching among all sensing joints and shores, necessitating additional hardware to exchange and demodulate the sensing information. In this study, we introduce a novel ISAC configuration tailored for the SMART network, with demonstrating the viability of detecting modulated sensing information using a communication-compatible digital signal processor (DSP). By applying frequency modulation (FM) and optical single-sideband (SSB) modulation to the sensing information obtained by the electronic sensors, we convert the information into multiple frequency subcarriers that reside near the communication spectrum without interference. We experimentally validated the proposed ISAC configuration using a two-span single-mode fiber (SMF) communication link, achieving real-time temperature monitoring on an FPGA platform at the sensing joint between two 50-km span SMFs. Furthermore, our findings indicate that employing high-order frequency subcarriers and an analog frequency multiplier for frequency chirp amplification of the FM sensing information enhances temperature estimation accuracy when using the communication-compatible DSP. With this approach, we achieved a temperature monitoring resolution of 0.0625°C, which matches the resolution limit of the DS18B20 sensing probe used, while maintaining full compatibility with 16-GBaud DP-QAM16 coherent communication data transmissions. At last, the scalability of the proposed ISAC configuration for the multiple-span SMART cable is further discussed.