Design and experimental demonstration of underwater wireless optical communication system based on semantic communication paradigm.

Underwater wireless optical communication (UWOC) has been widely studied as a key technology for ocean exploration and exploitation. However, current UWOC systems neglect semantic information of transmitted symbols, leading to unnecessary consumption of communication resources for transmitting non-essential data. In this paper, we propose and demonstrate a deep-learning-based underwater wireless optical semantic communication (UWOSC) system for image transmission. By utilizing a deep residual convolutional neural network, the semantic information can be extracted and mapped into the transmitted symbols. Moreover, we design a channel model based on long short-term memory network and employ a two-phase training strategy to ensure that the system matches the underwater channel. To evaluate the performance of the proposed UWOSC system, we conduct a series of experiments on an emulated UWOC experimental platform, in which the effects of different turbidity channel environments and bandwidth compression ratios are investigated. Experimental results show that the UWOSC system exhibits superior performance compared to the conventional communication schemes, particularly in challenging channel environments and low bandwidth compression ratios.

Unified statistical thermocline channel model for underwater wireless optical communication.

Understanding the effect of ocean turbulence on optical beam propagation is critical to the design and performance evaluation of underwater wireless optical communication systems. In this Letter, we propose a unified Weibull-generalized gamma distribution to characterize the laser beam irradiance fluctuations of turbulent underwater thermocline wireless optical channels. The proposed model shows an excellent agreement with the measured data under various experimental emulated channel conditions that cover turbulences induced by temperature, salinity, and air bubbles. To the best of our knowledge, this is the first model that comprehensively describes the statistics of the laser beam irradiance fluctuations in underwater wireless optical channels due to both thermohaline gradient and air bubbles.