Marine High-Speed Over-the-Horizon Communications and Channel Sensing in Evaporation Ducts over the South China Sea

Evaporation ducts (EDs) significantly affect marine communication signals. A proficient understanding of ED characteristics is crucial for enhancing the quality of marine communications. We conduct a high-speed, over-the-horizon communication link between the moving vessel and stationary shore over the South China Sea. Meanwhile, we propose an evaporation duct height (EDH) inversion method based on the communication signals to sense EDs. The packet loss rate, path loss (PL) and air-sea parameters are observed during the measurement. Our results showed that the S-band communication signals propagated for 44 km (2.3 times the line-of-sight) in the ED at a bit rate of 40 Mbps and a packet loss rate of 0%. A range of 70 km (3.7 times the line-of-sight) was reached with a bit rate >30 Mbps and a packet loss rate <1.5%. The EDH inversion method using communication signals showed great potential with a root-mean-square error (RMSE) of 2.6 m when compared with the predicted EDH. An interesting finding is that the temporally and spatially nonuniform ED may cause PL to decrease with the range increases. The combination of communication and channel sensing in EDs can provide real-time propagation conditions utilizing original communication signals and then improve the quality of communication.