Research On Wireless Channel Modeling In V2V And A2G Communication Environments

In recent years,with the rapid development of the wireless communication business and the emerging broadband mobile Internet access technology,the optimization of wireless communication system becomes very important.In reality,the understanding of the wireless channel has been the foundation of the design high performance and high spectrum efficiency of wireless transmission technology.Massive Multiple Input Multiple Output(MIMO)and vehicle-to-vehicle(V2V)communications as the most important technologies in the fifth generation(5G)mobile communications,which has manifested enormous superiorities in advancement of channel capacity and spectrum utilization rate.The performances of massive MIMO system mainly depend on wireless fading channel and transmitter-receiver array elements.The characteristics of wireless channel have great influence on signal transmission.Therefore,it is necessary to investigate the propagation characteristics between the transmitter and receiver in wireless communication environments.This paper mainly focus on V2 V channel modeling and air-to-ground(A2G)channel modeling,which establish a solid theoretical foundation in the performance evolution of wireless communications.The research of this manuscript is shown as follows:Firstly,we propose a generalized visual scattering channel model for dense urban street environments.The proposed model first separates the multi-bounced propagation paths into odd-and even-numbered-bounced propagation conditions.More importantly,general formulations of the marginal probability density functions(PDFs)of the angle of departure(AoD)at the Mobile Transmitter(MT)and the angle of arrival(AoA)at the Mobile Receiver(MR)have been derived for the given two conditions,respectively.From the proposed model,we derive an expression for the Doppler frequency due to the relative motion between the MT and the MR,which broadens the research of the proposed visual street scattering channel model.The results show that the proposed model can fit those of the previous scattering channel models and the measurement results for dense urban street environments very well,which validate the generalization of the proposed virtual street channel model.Secondly,we propose an irregular-shaped geometric channel model to describe the mobile radio communication environments.In the model,the impact of propagation condition along the street on the channel characteristics is investigated.Furthermore,the impacts of moving directions and velocities of mobile scatterers on the channel characteristics are investigated.The results demonstrate that the proposed scatterer distribution is suitable for macrocell and microcell communication environments,which can be used to design the performance of V2 V communication systems in 5G.Then,we propose a generalized three-dimensional(3D)non-stationary scattering channel model for V2 V communication environments,which simultaneously describe the angular arrival of multi-path signals.The model introduces a two-cylinder model to describe moving vehicles as well as multiple confocal semi-ellipsoid models to depict stationary roadside scenarios.We first derive the closed-form expression for the joint and marginal probability density functions of the AoD and AoA corresponding to the azimuth and elevation angles.Furthermore,we investigate the spatial correlation functions of the non-line-of-light(NLoS)rays scattered from the moving vehicles around the MT and MR,and the NLoS rays scattered from the roadside environments.The numerical results demonstrate that the proposed 3D non-stationary wideband channel model is practical for characterizing real V2 V channels.Lastly,we propose a computationally efficient approach to estimate the timevariant properties of A2 G channel models.To be specific,we first estimate the angular parameters in the preliminary stage before the UAV and MR move.Then,the real-time angular parameters are efficiently estimated based on the estimated angular parameters obtained in the preliminary stage and the time-varying properties of the model,which can be used to describe the real A2 G communication environments.The numerical and simulation results indicate that the non-stationary characteristics of the A2 G channel models,and simultaneously describe the dynamic properties of the time-variant multipath channel structure,which enrich the theory analysis of the movement of the channel modeling.