Multi-dimensional Hybrid Modulation Wireless Optical Communication System Based On Orbital Angular Momentum Keying

In recent years,with the rise of modern information technology industry such as artificial intelligence industry and Internets of Things industry,such as the continuous development of e-commerce,live delivery,video call and other large flow businesses,people’s demand for information is increasing,which leads to the need to further improve the network bandwidth.Therefore,in the development of the national economy and society,the question of how to improve the communication capacity of communication systems has become a burning question.Further exploring the resource dimension in the field of communication has also become an inevitable trend for the construction of modern high-speed,high-capacity communication technology.Free Space Optical Communications(FSO)has gradually become the focus of scholars because of its large capacity,wide spectrum,and strong anti-interference ability.In addition,the Orbital Angular Momentum(OAM)beam brings a new modulation dimension to space optical communication,which makes the OAM keyed FSO system attract a lot of scholars’ attention and research.For the OAM keying FSO system,under the precondition of interference of the problems of atmospheric turbulence,Multidimensional mixed modulation wireless optical communication system based on orbital angular momentum to promote the communication performance of the FSO system.especially the spectrum efficiency,enhance communication in free-space optical communication field follow-up research and development have brought more possibilities.In this paper,the result of a multi-dimensional hybrid adjustment depends on the angular momentum momentum to improve the effectiveness of optical communication systems.The space under the influence of the turbulence of the atmosphere has been checked,the main research and successis:Firstly,Based on Kolmogorov theory,this paper studied the influence of optical signal in the process of transmission in atmospheric environment in detail,and used power spectrum inversion method to simulate atmospheric turbulence through matlab simulation software phase screen.Secondly,Proposed and constructed OAM-SK-PPM-FSO hybrid modulation communication system.Firstly,SLM is used to modulate the fundamental mode Gaussian beam with OAM keying.Data symbols in space domain are represented by modulating four orbital angular momenta with different modes to the fundamental mode Gaussian beam.In the time domain,multi-dimensional hybrid modulation is realized by PPM modulation,and a phase screen simulating at mospheric turbulence is loaded during the propagation process.Third,The performance advantages of multi-dimensional hybrid modulation FSO system based on OAM keying under the influence of atmospheric turbulence are studied.The simulation results show that the spectral efficiency of OAM-SK-PPM-FSO system is better than that of WSK-PPM-FSO system under weak turbulence when using mixed modulation.The error bit performance of WSK-PPM-FSO system is better than that of OAM-SK-PPM-FSO system.