Research On Millimeter Wave LOS MIMO Transmission Technology

With the advancement of communication technology,various communication services are booming,and the demand for high-speed and large-capacity communication has increased sharply.Therefore,the proposal of air-space-ground integration has quickly become a research hotspot,and the near-space communication that needs to be developed is also attracting attention.However,the commonly used low-frequency spectrum resources are in short supply.To meet the long-distance and large-capacity transmission of air-to-ground,researchers have targeted the millimeter-wave frequency band with more considerable spectrum resources.However,the millimeter-wave will be attenuated by meteorological factors during the air-to-ground long-distance transmission.Due to the antenna aperture limitation,the transmission distance may exceed the Rayleigh distance,which affects the system transmission performance.Therefore,the air-to-ground millimeter-wave LOS MIMO system is studied.The new channel and transmission technology are of great significance to the development of nearby space communication.This thesis first studies the channel transmission characteristics of adjacent spaceto-ground communication,focusing on analyzing the influence of high-frequency electromagnetic waves on the troposphere.The random effect of atmospheric turbulence in the troposphere on the phase and amplitude is taken into account in the air-ground millimeter-wave LOS MIMO channel model.Then the channel capacity of the air-ground system is analyzed.Considering the optimal antenna arrangement;the emphasis is on the analysis of the atmospheric turbulence when the transmission distance meets the Rayleigh distance criterion and super-Rayleigh transmission,the channel capacity and the channel capacity of the air-ground system are analyzed.The impact of relevance.Finally,given the characteristics of fewer scatterers in the air-to-ground long-distance transmission environment and strong channel correlation,the simulation analysis is suitable for the precoding processing technology of air-to-ground long-distance transmission.The study found that the air-to-ground millimeter-wave LOS MIMO communication system can make the channel matrix orthogonal through reasonable antenna arrangement.The channel capacity and system performance are optimized.At this time,the transmission distance meets the Rayleigh distance criterion,but this orthogonality is easy destroyed by atmospheric turbulence,and the stronger the turbulence intensity,the more the channel correlation increases and the channel capacity decreases.When the transmission distance is far beyond the Rayleigh distance,the correlation of the channel matrix will gradually approach 1,and the channel capacity will decrease rapidly.At this time,atmospheric turbulence will reduce the channel’s correlation and compensate for the channel capacity to a certain extent.At the same time,it is found through simulation comparison that nonlinear precoding is more suitable for an air-to-ground transmission environment,especially in a strong turbulence environment,nonlinear precoding performance is better,and the channel matrix correlation is stronger,nonlinear precoding is anti-jamming the more obvious the advantages.