Research On The Modeling Technology Of UAV Air-ground Channel

From the beginning of its invention to now,unmanned aerial vehicle(UAV)has been greatly developed in all aspects,and has a broad market in the field of military communication and civil communication.The UAV can be fully applied mainly because of its obvious characteristics of low cost and flexibility.In order to better design the UAV Communication System and evaluate its superior performance,it is very necessary to carry out convenient,universal and appropriate modeling for UAV signal transmission.The research work of UAV air ground channel model needs to be rigorous and innovative.At present,due to the limitation of actual conditions,it is difficult to carry out the channel measurement for UAV,so it is difficult to obtain sufficient measured data.Therefore,it is necessary to study the channel modeling of UAV from other angles.Therefore,the geometric based stochastic model understands the channel characteristics by planning the distribution of scatterers in a specific regular geometric range and analyzing them.However,the current general work does not take the geometric model as the complete basic framework,so as to achieve a clear analysis of the specific scattering distribution of the signal transmission space between the UAV and the ground,and there is no specific modeling and analysis according to the actual scene and measured data.Therefore,this paper deduces the regular geometric signal propagation model based on half cylinder for the first time to express the actual propagation environment with the ground end,deduces the space-time correlation function and Doppler power spectral density,and then studies and analyzes it based on the specific results.Specifically,the main work of this paper includes:1.There are different states during the flight of the UAV,and the channel is divided into different scenarios for discussion.The small-scale fading parameters such as aircraft Doppler frequency shift and delay spread in different scenarios are different,and different channel models need to be established.In this paper,the air-ground channel is divided into several different scenarios of flight,take-off and landing,and stop states.2.According to the signal transmission scene in the actual flight process,a channel model based on a half cylinder is proposed for the first time.The scatterers are distributed in the half cylinder,and the received signal is the sum of the direct path(LOS)component,the ground single point reflection component and the single reflection ray component near the ground end.Based on the model,some important statistical characteristics are derived and studied,including space-time correlation function and Doppler power spectral density.At the same time,some simulation results are provided to verify that the variability of Doppler power spectrum obtained by UAV in different flight directions is consistent with the actual scene.The establishment of channel model is the analysis of the signal from the transmitting end to the receiving end at a certain time.This work plays a very important role in the evaluation of the actual effect of channel transmission.3.For modeling the measured channel,by selecting an appropriate measurement scheme,the corresponding channel model parameters are extracted and used as the source of all parameters for subsequent channel modeling.Firstly,according to the measured data,the disturbance in Yunnan area is described and analyzed in detail.Secondly,according to the eigenvalues extracted from the measured data,the simulation work of the channel model is completed.The accuracy of the multipath delay is judged by the multipath delay(PDP)of the simulation results,and the multipath profile of this type of channel model can be observed through the scatter function.It can be seen from the PDP diagram that this work is to show the results of channel transmission corresponding to the channel model according to the analysis of the received signal in a certain time and long range,and it can be seen that there are multiple paths of the received signal,so it is very necessary for the construction of the channel model.Finally,the visualization interface diagram of the channel model and the interference interface are shown.