Transmission Characteristics of High-Frequency Underwater Acoustic Channels with High-Frequency Marine Noise in Shallow Sea

High-frequency coherent underwater acoustic (UWA) communication technique has the characteristics of large bandwidth, high data rate, and high directivity, which provide the possibility for high-speed robust point-to-point transmission in UWA sensor networks. As of now, there are few researches on high-frequency UWA channels. In this paper, we investigate the transmission characteristics of high-frequency UWA channels with high-frequency background noise in shallow sea. Firstly, we present the physical characteristics of high-frequency UWA channels, including multi-path effect, Doppler Effect, and marine background noise at high-frequency. Then, the multi-scale time-varying UWA channel (MTUAC) model is introduced to compare with the field test results of high-frequency UWA channels in two sea areas along the coast of Fujian, China. Finally, the transmission characteristics of mid-low- and high-frequency UWA channels are simulated by using the MTUAC model respectively. The differences in characteristics (multi-path structures and Doppler spread) between the two kinds of UWA channels are highlighted. The results show that due to attenuation and scattering, the number of multi-path in high-frequency UWA channel is less than that in mid-low-frequency UWA channel. In addition, the time variation and the Doppler spread of high-frequency UWA channel are relatively more serious.