| Vehicle-mounted ultrashort wave radios are widely used in wireless communication of land warfare,but their communication range and quality are susceptible to actual battlefield terrain.In tactical wireless communication,complex terrain such as plains,mountains,jungles and hills can affect the radio wave propagation characteristics of vehicle-mounted wireless communication antennas,which causes an increase in path loss and decreases in communication distance and communication quality.Therefore,the study of the radio wave propagation model which is used for predicting the communication distance and communication quality,is of great significance to evaluate the working state of communication equipment and improve communication supportability in actual combats.The topic of this thesis comes from the project " Construction and Analysis of Vehicle Communication Radio Distance Model".In order to predict the ultrashort wave propagation in a complex battlefield environment,a radio wave propagation prediction model of vehiclemounted ultrashort wave radio including terrain and antenna information is established by using the ray-tracing method and machine learning algorithm,and the accurate prediction of path loss of ultrashort wave propagation is accomplished.The main research work of this thesis is as follows:1.The ultrashort wave propagation theory and classical wave propagation model are studied.Based on the theory of radio wave propagation,the propagation modes of direct,reflective,diffraction,and scattered waves are studied.The propagation characteristics of ultrashort wave are expounded,and the advantages and applications of ultrashort wave communication are discussed.The main characteristics and application range of classical radio wave propagation models suitable for ultrashort wave band are analyzed.2.A radio wave propagation simulation model of vehicle-mounted ultrashort wave radio is established based on the ray-tracing method.With the integrated simulation modeling of a combat armored vehicle and a vehicle-mounted antenna,the radiation characteristics of the antenna at different working frequencies on the vehicle-mounted platform are studied.Combined with the electronic map model of the actual terrain,a radio wave propagation simulation model of vehicle-mounted ultrashort wave radio suitable for the land battlefield environment is established.The influencing factors of propagation path loss in tactical wireless communication are analyzed by using this model.The accuracy of the model is verified by comparison with AREPS calculation results.3.The radio wave propagation prediction models of vehicle-mounted ultrashort wave radio are established by using the machine learning algorithm.According to the results of the simulation model,the prediction models of radio wave propagation are established based on machine learning algorithms of random forest,BP neural network,linear regression,and knearest neighbor.The prediction performance of each model is evaluated by evaluation indicators such as root mean square error and coefficient of determination.The results show that the random forest model performs the best,that the coefficient of determination reaches0.9601,and that the root mean square error reaches 2.1901.Compared with classical radio wave propagation models such as Egli and Okumura-Hata,the random forest model has higher accuracy and can accurately predict radio wave propagation path loss. |
