Research On Key Technology Of Communication System Based On OAM

Orbital Angular Momentum(OAM)communication is a novel technology that utilizes different dimensions of electromagnetic waves for information transmission.Recently,this technology has received extensive attention because OAM has an infinite number of orthogonal modes,allowing multiple data streams to be transmitted simultaneously in a single fiber or free space,thereby significantly improving the capacity and spectral efficiency of communication systems.OAM communication involves the generation,reception,transmission,and application of OAM electromagnetic waves.This thesis mainly introduces the basic principles and related technologies of OAM communication and analyzes its advantages and challenges.Firstly,the concept and characteristics of OAM and how to generate vortex electromagnetic waves(electromagnetic waves with OAM)are introduced.Vortex electromagnetic waves have a vortexshaped phase structure and five basic characteristics: quantum nature,stability,orthogonality,divergence,and reflection.Secondly,the reception technology and mode detection technology of vortex electromagnetic waves are discussed.Vortex electromagnetic waves can be received in two ways: complete aperture or partial aperture.The former requires receiving the entire beam,while the latter only requires receiving part of the beam.The mode detection technology mainly includes two methods: phase gradient method and circular array reception method.The former identifies a single mode by calculating the phase difference between adjacent receivers,while the latter identifies multiple modes by parallel processing signals using multiple receivers.In addition,this thesis also proposes a novel dualmode detection method,which combines amplitude information and phase information for dualmode detection and has better anti-interference performance than traditional methods.Then,a non-orthogonal transmission channel model based on OAM is established,and its performance in free space channels is analyzed.The channel capacity between different modes is calculated under different parameter conditions,and the impact of mode multiplexing on system capacity gain is evaluated.A OAM-MUSIC super-resolution algorithm based on a uniform circular array(UCA)is also derived,and two OAM beam models,multi-transmitter multi-receiver and multi-transmitter single-receiver,are constructed.Its performance in dual-target detection under different azimuth angles is verified through simulation experiments,demonstrating its high-resolution characteristics.Finally,the impact of circular array errors on generating vortex electromagnetic beams is discussed,considering the effects of array radius error and azimuth angle deviation on the purity of vortex electromagnetic beams,and the relationship between the purity of vortex electromagnetic beams and the transmission distance and reception array radius is analyzed.At the same time,an interval analysis algorithm is introduced to estimate the upper and lower bounds of beam amplitude,and its correctness is verified through Monte Carlo simulation.In summary,this thesis provides a detailed introduction to the basic principles,related technologies,and advantages of OAM communication,as well as analyzing the challenges it faces and solutions to these challenges.The research in this thesis has important theoret-ical significance and practical application value for promoting the development of OAM communication technology.