Research On Modeling Of Transfer Characteristic Of Orbital Angular Momentum In The Wireless Communication

With the continuous development of communication technology,the wireless communication system tends to be in the direction of high speed and high bandwidth.With the popularization of intelligent terminals and the continuous development of the Internet applications,the contradiction between the demand for capacity and the shortage of spectrum resources is becoming more and more serious.The orbital angular momentum technique can greatly improve the system capacity without increasing the bandwidth,which makes the research and application of the orbital angular momentum technique in the wireless communication system become more and more popular.At present,the application of electromagnetic vortex wave in the wireless communication system is still in the exploratory stage,there are still many problems to be solved.Based on the basic properties of orbital angular momentum,in this paper the orbital angular momentum of the wireless communication system is modeled,and the transmission characteristics of the electromagnetic vortex wave carrying orbital angular momentum are studied.In the process of transmission,the electromagnetic vortex wave will be affected by the atmospheric turbulence and other factors,so that the torsional angle of the phase changes and so as to destroy the electromagnetic vortex wave.This paper provides some theoretical support for the problem of capacity requirements and the shortage of spectrum resources,so as to speed up the popularization of intelligent terminals and the development of the Internet.The main results and conclusions are as follows.(1)This paper presents a model of orbital angular momentum in the wireless communication system.The model of photon orbital angular momentum is applied to the low frequency,and the electromagnetic vortex wave model similar to the Laguerre-Gauss vortex beams is build,and the electromagnetic vortex wave of 30GHz was simulated by using Labview software.This lays a theoretical foundation for the further development of the research work in this paper.(2)In this paper,we study the transmission characteristics of the electromagnetic vortex wave in ideal channel by Labview simulation software.When the electromagnetic vortex wave carrying orbital angular momentum transmits in the ideal channel,the distribution of electric field is divergent,the beam broadening phenomenon occurs,and the energy loss occurs;the phase distortion occurs,and the phase line bends.Then we study the effect of distance,wavelength and beam radius and other parameters on the transmission characteristics of the orbital angular momentum,with the transmission distance of orbital angular momentum increases in ideal channel,electromagnetic vortex wave changes gradually serious;when the transmission distance is 0,the phase distribution of electromagnetic vortex wave is only determined by the modal of the orbital angular momentum.(3)In this paper,the propagation characteristics of electromagnetic vortex waves in atmospheric turbulence are studied.The loss of waveform is more serious transmitting in atmospheric turbulence than that in ideal channel when the distance is the same;with the absolute value of orbital angular momentum increases,the electromagnetic vortex waves are affected more deeply by atmospheric turbulence;when the orbital angular momentum is in the same size and opposite sign,the electromagnetic vortex waves are affected by atmospheric turbulence in the same degree.Then the influences of different transmission distances and different atmospheric turbulence intensity are studied.Finally,a transmitter diversity scheme is proposed to decrease the effect of atmospheric turbulence,and without regard to space and cost constraints,the more the number of transmit antennas is,the better the effect is.