Modeling And Simulation For UAV Wideband Channels

Unmanned Aerial Vehicle(UAV)will have a variety of applications in the future because of its low cost and high flexibility.With the continuous development of UAV-related industries,UAV communication technology has gradually become a new hot topic in wireless communication research.It is crucial for the development of UAV communication technology that a reasonable and reliable UAV channel model can be proposed.Considering the fact that UAV channel measurements and data obtained from actual measurements are still lacking,geometry-based statistical channel models can help us quickly have a study on the channel statistics,which can be used as a reference for future measurements of actual UAV channels.In this paper,a generalized wideband regular geometry-based statistical r-eference channel model f-or the UAV-MIMO scenarios is proposed.In order to describe the movement of the UAV in three-dimension,a sphere model is adopted to account for the combined effects of vertical and horizontal angles.And to describe the wideband channel characteristics,the narrowband sphere model has first been established and then expanded into a wideband concentric-sphere channel model.The model consists of a line-of-sight component,a single-bounced component for the transmitter,a single-bounced component for the receiver and double-bounced component.This model can be applied to narrowband or wideband UAV communication channels in various environments by appropriately adjusting parameters such as path power ratio in the model.Secondly,based on the proposed UAV wideband and narrowband channel reference model,close-formed expressions of second order channel characteristics such as space-time-frequency correlation function,Doppler power spectral density,power delay spectrum,envelope level crossing rate and average fading time in three-dimensional non-isotropic scattering environment are derived.Varying wideband and narrowband channel characteristics in different scenarios are obtained with different UAV flight parameters such as direction of motion,speed,antenna orientation,and flight altitude.Combined with the actual UAV scenarios,the reasons for the influence of the UAV flight parameters on the statistical channel characteristics are discussed reasonably.Some suggestions for the design of the UAV communication system are also proposed.The simulation results show that the UAV flight parameters and the scattering environment have a joint effect on the statistical channel characteristics,and the UAV flight parameters can be adjusted to achieve more stable UAV-to-ground communication.Finally,the deterministic and stochastic simulation models based on the narrowband and wideband UAV-MIMO reference models are proposed.The simulation models are based on the sum-of-sinusoids method.Since the horizontal and vertical angles of the sphere models have a joint probability density function,the traditional modified equal area method is improved in this paper.The statistical characteristics of the simulation model channel are also derived.The simulation results show that the simulation model can reasonably reproduce the channel statistical characteristics presented by the reference model while reducing the complexity of the model,which proves the practical availability of the proposed two simulation models.Compared with the measured data in different scenarios,the accuracy and generality of the proposed channel model are proved.