Analysis And Research Of Channel Model Characteristics And Connectivity In Internet Of Vehicles

The Internet of vehicles(IoV)is an important part of future communication.In order to ensure the reliability of high-speed information transmission under the complex urban environment and the dynamic state of various vehicles,it is urgent to model the wireless channel accurately,which is the basis of Vehicle-to-Vehicle(V2V)broadband wireless communication.With the continuous improvement of communication data transmission rate,the study of channel characteristics refinement is particularly important.Accurate channel modeling can not be separated from the measured data in real environment and the corresponding modeling research.In order to solve the above problems,this dissertation studies the measurement and modeling of broadband channel in V2V scene and the connectivity of the response channel model.Based on the complex scene of V2V communication in IoV and the changeable characteristics of the receiver and transmitter’s motion state,the measured channel data of several motion states in various typical scenarios are analyzed in detail.The timevarying high-speed channel model is established to analyze the time-varying characteristics of the channel.At the same time,the link connectivity performance of V2V is studied based on the channel propagation characteristics.The contributions and innovations of this dissertation are as follows:(1)The quasi-stationary time and the statistical characteristics of V2V channel under various driving states are studied.In this dissertation,broadband signal measurement scenarios under various moving states are designed.After deriving the measurement data of three typical vehicle motion scenarios(two vehicles in the same direction,vertical driving and opposite driving),the method of obtaining power delay spectrum is analyzed.According to the fast time-varying characteristics of V2V channel,the correlation matrix and quasi-steady-state time under different environments and driving conditions are obtained by using correlation matrix discrimination method to calculate the channel delay power spectrum.According to the analysis of non-stationary characteristics under different driving conditions,the relative speed of the transceiver is the main factor affecting the non-stationary characteristics of the channel.(2)The time-delay power spectrum and scattering function of various typical V2V scenarios are studied.In order to study the channel characteristics of various complex scenes and moving states in V2V scenario,the dissertation raises how to analyze the time-varying Doppler power spectrum of three typical driving scenarios,parallel,reverse and vertical driving,which is based on the frequency selective channel theory.The analysis results show the characteristics of time dispersion and frequency dispersion in the vehicle-vehicle fast time-varying channel when two vehicles move at the same time.The results can be used as the basis for V2V channel modeling and channel simulation,and according to the Doppler characteristics of different scenes,the performance limit and pilot structure of the equalizer can be designed in advance.(3)The V2V channel model based on ellipse model and ellipsoid model is studied.The 2D ellipsoid model is used to model the V2V broadband channel.Different ellipses are formed with two vehicles as the focus to simulate different time delays.The Doppler power spectrum is calculated by using elliptic integral.The channel scattering function and time-varying Doppler power spectrum under different vehicle motion conditions are simulated and compared with the measured data,which proves the accuracy of the modeling.In view of the fact that the reflector has a certain height in V2V channel,3D ellipsoid theory is used to model V2V channel,and ellipsoid integral is used to calculate Doppler power spectrum.The Doppler power spectrum of the V2V channel under different motion states of the reflection of the buildings along the street is obtained by modeling and calculation.The model established in this dissertation is helpful to reveal the complex characteristics of Doppler domain in V2V scene.(4)This dissertation studies the V2V connectivity probability in the case of LoS /OLoS / NLoS in various traffic flow environments.This dissertation analyzes the largescale channel model under different traffic density,and decomposes the characteristics of the small-scale channel model of LoS / OLoS / NLoS caused by vehicle occlusion in the process of driving.Combined with the measurement of rice K factor in different states,the time domain signal is modeled by Suzuki process.In addition,this dissertation simulates the traffic flow,and adds the V2V channel fading model considering the change of traffic density and vehicle occlusion,and proposes the V2V link connectivity model considering the measured data,and simulates the V2V link connectivity under different road loss thresholds,and the influence of special weather on electromagnetic wave has also been taken into account.The results can reflect the link connectivity performance in the practical application of Internet of vehicles.