Abstract:Shallow water acoustic channels presents random time-space-frequency characteristics, which brings great challenges to reliable data transmission.Polar codes with low complexity and theoretically proven that can reach the Shannon limit, which can enhance the robust of underwater acoustic communication systems.Image, voice, text, ocean monitoring data and remote control commands are transmitted underwater with characteristic of unequal importance.The multi-rate Polar codes can adapt to underwater acoustic channels conditions and information transmission of unequal importance.At present, the application study on Polar codes to underwater acoustic communication is mostly simulation analysis.In this paper, a group of multi-rate Polar codes are designed to sea trial in Xiamen Port,meanwhile,analysis under recorded ambient noise with different signal-to-noise ratios.The sea trail results show that under good channel conditions, the performance of the Polar codes are excellent,BPSK and QPSK with a bit rate of 0.25 achieve zero bit errors when the SNR of the recorded ambient noise is -1 and 4.The multi-rate Polar codes with low-complexity channel encoding and decoding mechanism can match the underwater acoustic channel and effectively improve the reliability and effectiveness of underwater acoustic data transmission,the robust and reliable underwater acoustic communication system based on Polar codes is verified by sea trials.