Underwater Wireless Optical Communication Simulation System For Digital Twin

Underwater wireless optical communication(UWOC)has attracted widespread attention because of its advantages such as strong anti-interference,high bandwidth and good confidentiality.However,there are still some difficulties and challenges in the application and development of this technology:(1)Light transmission has space-time and time-varying characteristics.That is,the absorption and scattering effect of seawater in the process of light transmission under water will cause loss of light energy,limit the effective transmission distance of light underwater,and the scattering effect of seawater will also lead to changes in the direction of photon propagation,thus affecting the performance of underwater wireless optical communication system.At the same time,due to the existence of uncertainties such as ocean turbulence,the light intensity,phase and transmission direction of light transmission will change randomly,so the underwater wireless optical communication system needs to be designed according to the specific channel environment.(2)In the complex and changeable marine environment,the optical parameters of the ocean vary greatly in different sea areas,different seasons and different depth conditions.Therefore,it is difficult and extremely expensive for researchers to verify the performance of underwater wireless optical communication systems in key sea areas in real time and field tests.In view of the above problems,this paper introduces the idea of digital twin(DT),designs and develops an underwater wireless optical communication simulation system for digital twin,which can adapt to the changing channel environment,and can test and evaluate the performance of underwater wireless optical communication systems in key sea areas by connecting with the global ocean optical database independently developed by the research group.The specific research content is summarized as follows:(1)According to the absorption and scattering characteristics of seawater light,the characteristics of underwater wireless optical communication channels were studied.The intrinsic and apparent properties of seawater were studied;The attenuation characteristics of received light intensity with transmission distance under different water quality conditions were compared and analyzed.The existing marine optical sensors are introduced,focusing on the relevant observation data provided by ocean water color satellites and Argo buoys,and the marine optical parameters at different depths in key sea areas are inverted.(2)The underwater wireless optical communication system and its principle were analyzed and studied.The model of underwater wireless optical communication system,the commonly used modulation methods,photodetectors and their principles were introduced,and the performance of different modulation methods was compared and analyzed.The basic characteristics and basic components of digital twin and the typical application scenarios of digital twin are elaborated,and how to apply it in underwater wireless optical communication simulation system is analyzed.(3)According to the marine water color data of different profiles provided by the marine optical sensor,the marine optical parameters at different depths in key sea areas and depths were inverted,and the light field distribution model of the underwater wireless optical communication system was derived by combining the Monte Carlo numerical simulation method.Combined with the light field distribution,the bit error performance of light transmission at different depths under different modulation modes is obtained through simulation analysis.(4)Design and develop an underwater wireless optical communication simulation system for digital twins.By connecting with the marine optical database,the simulation system can obtain the marine optical parameters under the corresponding conditions from the database according to user needs,simulate the receiving light field distribution model of the underwater wireless optical communication system,and obtain the light field distribution of the underwater wireless optical communication system in different seasons and depths in key sea areas.Combined with the optical field distribution,the bit error performance of the receiving end under the corresponding conditions is simulated,and the performance of the underwater wireless optical communication system in key sea areas is realized.