The Analysis Of Channel Characteirstics In The Underwater Laser Communication System

Since the21st century, in order to safeguard maritime rights and interests,enhance the development and protection of marine resources, and monitor ecologicalenvironment, underwater detectors, underwater environmental monitoring,underwater imaging technology and underwater wireless communication networkhave been widely applied. To achieve real-time monitoring and transmission of largevolumes of data produced by these detection techniques, it relies on a high datatransmission rate of wireless underwater communication technology. the wide-bandand big-capacity underwater laser communication is not easily affected by changesof temperature and salinity, so it has a good anti-jamming capability. Further, thelaser has a strong directivity and improves the security during the informationtransmission.Information transmission characteristics in the channel directly affects the qualityof the communication system. Underwater laser communication system based onpure water or seawater as transmission medium, the attenuation effect to the laser inthe water is an important influence factors in the system design. In addition to thewater molecules in the sea, it also contains numerous suspended particle, solublematerials and organisms, led to the attenuation due to absorption and scatteringeffects in the light propagation. Therefore, study of optical properties of channel isthe key to the design of communication system.In view of the attenuation of underwater channel to the light, this paper firstlyanalyzes the inherent optical properties of sea water, to understand the lightabsorption and scattering effect of the substance in the water. By studying theradiative transfer equation of the underwater light, the monte carlo method tosimulate energy attenuation of underwater light is put forward. An underwater lasercommunication system is set up in the laboratory, through transmissing the different signals under the water with the different quality, the attenuation effect ofunderwater channel to laser and the BER of the system are analyzed in theexperiment. As can be seen from the results, with the loss of the visibility, theattenuation effect of the channel to the laser is remarkably mannified and the BERalso increased.