Joint Optimization Of UAV Air-ground Channel Based On Scatterer Densit

Unmanned Aerial Vehicle(UAV)plays an important role in the wireless communication field as a base station,data acquisition terminal and communication relay.The characteristics of UAV such as high mobility and deployment flexibility make the channel state of air-to-ground link have strong randomness,which brings great challenges to the establishment of channel model and the design of handover method.Therefore,based on the actual requirements of UAV air-to-ground communication system,the channel model and handover of UAV air-to-ground link are jointly optimized from three dimensions: environment,method and parameter.Aiming at the limitation of describing air-to-ground channel by single channel model,an air-to-ground channel model based on different scatterers density is constructed.In sparse scatterer environment,an improved RS＿NGSM stochastic channel model based on Loo model is constructed.Through the optimization of model parameters and the derivation and calculation of the analytic solution of bit error rate,the channel performance can be calculated in real time according to the measured data and the lightweight calculation cost can be realized in the practical engineering application.A Three-Dimensional(3D)EC＿GBSM geometric channel model based on ellipsoid and ellipsoid cylindrical structures is constructed in a dense scatterer environment.A Non Line of Sight(NLoS)channel model composed of ground reflection and multiple scatterer reflection is established,and the model is approximated to achieve the balance between accuracy and complexity.von-Mises distribution and cosine distribution are introduced to constrain the distribution and height of the scatterers,and then the relevant statistical characteristics of the model are obtained.Aiming at the constraints of a single decision parameter on the improvement of UAV handover performance,an adaptive channel handover method based on multi-parameter joint decision is designed in this study.Multiple parameters are used for joint decision,error rate feedback correction is added,and the minimum waiting period decision is used to constrain handover.Finally,the proposed channel model and handover method are simulated and tested in this study.The experimental results show that the UAV air-to-ground channel model constructed in this study is effective and accurate,and has a good fit with the measured data.Compared with the traditional algorithm,the proposed adaptive handover method can effectively improve the handover success rate and reduce the handover ping-pong rate.It provides valuable support for the design and optimization of UAV communication system in engineering applications.