Research On UWB Vehicle Channel Measurement And Modeling

Intelligent vehicles are gradually entering the market,and the booming evolution of wireless communication technology has caused widespread attention to on-board wireless signal transmission systems.Moreover,due to their freedom from time and space constraints as well as high information transmission rates,they have gained higher research significance and value.Among them,ultra-wideband(UWB)wireless communication technology stands out in this short range wireless communication technology relying on its high transmission rate,high accuracy,high security,low power spectrum,and other characteristics.Although there has been a lot of research on wireless communication technology so far,the existing research is not sufficient for harsh environments such as vehicle environments,where there are many metal reflective objects within a short distance.Modeling channels in different parts of a vehicle in different environments is essential for designing wireless sensor systems with strict specifications.The three experimental measurement scenarios selected in this thesis are all scenarios with important application value in objective reality.Considering that most of the existing studies only consider a single scenario,in this thesis,the selection of the latter two experimental scenarios reflects the linkage of on-board wireless communication systems,and factors that may affect wireless communication are introduced in the measurement process for parameter comparison.Through comparison,it can be concluded whether the potential influencing factors studied will have an impact on UWB signal transmission in this measurement scenario,and what impact will be obtained,providing valuable reference suggestions for the future design of on-board wireless sensor systems.In addition,the analysis of the results shows that there is a significant correlation between the models generated from the vehicle passenger compartment and the models defined in IEEE 802.15.4a in industrial scenarios.The main work and contributions of this article are as follows:Firstly,the propagation characteristics of UWB wireless signals are analyzed from large-scale fading and small-scale fading,and the methods and principles of UWB channel measurement involved in this thesis are introduced in detail.The important parameter extraction methods involved in the path loss model and the multipath delay model are described respectively.In addition,the on-site implementation methods of the experimental measurements in this article are described and verified for feasibility.Secondly,research was conducted on the wireless channels in the passenger compartment,from the engine compartment to the passenger compartment,and from the chassis to the passenger compartment.In addition to considering the channel model in a single compartment,the wireless channels between compartments were also analyzed,and the interaction between compartments was added.It was found that when wireless signals propagate across compartments,energy loss is more severe,and the arrival rate of clusters and rays is lower.The study of parameters in channel models is also more complex.Thirdly,different potential influencing factors were selected for comparative studies under various experimental scenarios.Modeling and analyzing the wireless channel in the passenger compartment of a vehicle under full-load and no-load conditions.When analyzing the wireless channel of the engine cabin and passenger cabin,it is considered whether the engine is switched on or off.When studying the wireless channel from the chassis to the passenger compartment,the engine status factors and three different road conditions(cement flat,grass,and muddy road sections)were introduced.After analysis,it is found that the presence of passengers can affect the wireless channel in the passenger compartment,including path loss,energy attenuation,and arrival rate of radiation within the cluster and cluster.Whether the engine is turned on or off will have a significant impact on the path loss in the channel from the engine compartment to the passenger compartment.From the vehicle bottom to the passenger compartment,while the impact on the energy attenuation of the cluster and the radiation within the cluster is relatively small.However,different road conditions have a significant impact on the path loss,energy attenuation of the cluster and radiation within the cluster in the wireless channel from the vehicle bottom to the passenger cabin,while the impact on the arrival rate of the cluster is very small.Fourthly,when analyzing and studying wireless channel models under three scenario settings,important parameters were extracted.Also,their impact on the parameters was obtained by comparing parameters under different influencing factors.When extracting model parameters,after preliminary processing and transformation of the data,least squares curve fitting and linear fitting based on Least Mean Square(LMS)criterion were used,respectively.The path loss model involves path loss index,reference path loss,shadow value,and path loss frequency dependence.The multipath delay model considers the energy attenuation coefficient of the cluster and the rays within the cluster,the time dependence of the ray attenuation factor,and the arrival rate of the cluster.Finally,the content of the full text is summarized,and the future prospects for research on vehicular UWB wireless channels are presented.