Analysis Of Visible Light Propagation Characteristics Through The Turbulent Atmosphere And Its Influence On The Communication Performance Of Traffic System

Visible light communication technology is an optical communication technology that uses a LED light source,which can emit bright and dark flickering light signals as a signal generator.In this communication,wider frequency bandwidth is available.Visible light communication technology has large communication capacity,high transmission rate and strong anti-electromagnetic interference capability.This communication has a good research prospects.Nowadays,people have higher and higher requirements for communication technology,and the application is also wider.But electromagnetic communication is facing a problem that there is fewer available frequency bands than before.Besides,it's communication speed and communication quality are unable to satisfy people's demands.So it is of vital important to come out a new and efficient wireless communication technology.This topic has become the research focus of major universities and electronic products companies.With the rapid development of LED technology,it has laid a solid foundation for the research of visible light communication technology.Domestic and foreign scholars have also carried out systematic research on visible light communication technology.In this paper,firstly,the influence mechanism of turbulent atmosphere on visible light communication system is analyzed,and the affect of various parameters in turbulent atmosphere on the communication performance of visible light communication system is deeply explored.At the same time,the transmission link equation of visible light signal under the impact of atmospheric turbulence is calculated and deduced,and the effect of different parameters on the transmission power of optical signal on the communication link is qualitatively analyzed.By means of mathematical modeling and mathematical statistics,an intelligent traffic visible light communication system model is established under ideal atmospheric conditions,which consists of two parts: line-of-sight transmission and diffuse reflection light path.The turbulence distribution model is used into the geometric model of the established visible optical traffic communication system in order to calculate the structural parameters of the whole communication system.The effects of signal-to-noise ratio,aperture size,visibility,wavelength and waist radius on bit error rate and channel capacity of visible light communication are calculated and analyzed.In addition,the effects of OOK,DPSK and PPM modulation modes on the communication performance of the system are compared.At the same time,the impact of special atmospheric environment such as rainy day,foggy day and snowy day on the receiving power of the system is systematically analyzed.The distribution maps of output power,bit error rate and channel capacity are further presented,and the effective coverage range of visible light communication in the transportation system is given intuitively.The important conclusions are as follows:(1)The size of aperture,visibility,wavelength,waist radius and atmospheric refraction structure constants all affect the transmission power of the system,which results in the change of channel capacity and bit error rate.The transmission power is proportional to the visible light wavelength,receiver aperture,beam waist radius and atmospheric visibility,and inversely proportional to the atmospheric refraction structure constant.With the increase of system power,the channel capacity of the system will increase and the system bit error rate will decrease.(2)In a clear atmosphere,the communication system between the signal lamp and the vehicle can achieve effective communication in the range of 100 m,and the communication system between the vehicle and the vehicle can achieve effective communication in the range of 110 m.However,with the increase of rainfall and snowfall,and the decrease of visibility,the effective communication distance of the system will gradually shorten,while in the case of dense fog,heavy rain and heavy snow,It is almost impossible to achieve effective communication.(3)Compared with DPSK and OOK modulation,the performance of PPM modulation is better.With the increase of the number of slots selected by sampling decision,the communication performance of PPM modulation will be gradually optimized.The simulation results based on this model are basically consistent with the actual situation.The relationship between transceiver and environmental parameters and transmission power,bit error rate and channel capacity of the system has been given in detail in this work.By properly selecting and adjusting the parameters of the system,the communication performance of the intelligent transportation system can be effectively improved.It also can provides some reference for the application of visible light communication.