Research On Infrared Scattering Communication Technology

Optical scattering communication is a communication method using the Rayleigh or Mie scattering happens to optical signal and atmospheric molecules or aerosol particles in the air channel.It has a broad application prospects because of the advantage of non-line-of-sight.The emission source in previous researches about scattering communication were tend to adapt ultraviolet light owing to its minor background light interference.But the communication distance was restrained with transmitting power due to its short wavelength and elements safety.In this thesis,we research a communication method which uses pulsed laser to generate infrared light to get a higher instantaneous power.Moreover,the wavelength of the infrared light source is longer than ultraviolet.It is easy to have a strong Mie scattering effect on the aerosol particles in the atmospheric channel.Therefore,infrared light scattering communication has a longer non-line of sight transmission distances.In this thesis,we carry out the infrared light scattering communication system modeling,introduce the atmospheric channel particle composition and their impact on the infrared light.And we use the single scattering model to derive the path loss of the infrared light during the transmission process,and carry on the detailed numerical analysis to each function and the variable parameter which probably affect the path loss.The analysis shows that influences of the system path loss are the transmission distance,transmitting and receiving elevation,receiving the field angle and the asymmetry factor.In this thesis,according to the requirements of the communication performance of the system,the OOK(On-Off Keying)is selected as the modulation mode and the direct detection is chosen to convert an optical signal into electrical signal.This thesis also analyzes the noise type in the receiving end.Based on the transmission rate and BER,we give corresponding relationship between the transmit power of the transmitter and the distance of non-line-of-sight transmission.At the same time,in order to reduce the transmitting power to meet the requirements of current parameters of laser,we use an optical antenna which has a structure with multiple-input-single-output(If we use four transmit antennas,the average transmission power can be reduced by 15 d B).In the end,we demonstrate the feasibility of this system by theories and experiments,and put forward the development requirements of the important equipment in infrared light scattering communication system.The research of this thesis can offer a corresponding theoretical basis for the development of the infrared light scattering communication test model,provide a non-line-of-sight telecommunication mode,and add a possible communication method for emergency communication and military communication in complicated environment.