Research On Wireless Channel Modeling In Industrial Internet Scenarios For 5G

The Fifth Generation Mobile Communication System(5G)has shifted the service focus from individuals to vertical industries for the first time.With the gradual improvement of 5G technology and the deployment of 5G around the world,the application of 5G in the industrial has become the development trend of intelligent manufacturing in factories in the future.Industrial Internet of Things(IIoT)is an example of communication technology empowering industrial manufacturing.Compared with wired communication,the application of wireless communication technology in industrial scenarios has the characteristics of low cost,flexibility,and easy maintenance.Wireless communication can bring profound changes to the development of manufacturing industry.The IIoT has become the key competitiveness of the country.At present,countries all over the world have begun to explore the combination of 5G and IIoT.Channel characteristics determine the upper limit of wireless communication systems,and wireless communication modeling is the basis and premise of mobile communication system design,evaluation and optimization.Compared with the traditional indoor scenarios,the IIoT scenarios has the characteristics of diverse scenes,rich metal scatterers,moving objects,and electromagnetic noise radiation from working equipment.In order to realize the deep integration of 5G and IIoT,it is necessary to establish a channel model suitable for 5G IIoT scenarios to accurately characterize the wireless channels in IIoT scenarios.This thesis uses the method of statistical modeling,build a broadband time-domain channel measurement platform,selects the IIoT scenarios,and carries out channel measurement activities according to the characteristics of the IIoT scenarios.Based on the collected measured data,the signal propagation mechanism is analyzed and compared.The channel characteristics at different antenna heights are studied,and the frequency dependence of the channel in this scenario is studied under the condition of ensuring the comparability of different frequency channels.The main research content and innovation points of this thesis are as follows:(1)Channel platform construction and channel measurement in the IIoT scenarios.This thesis takes the IIoT scenarios as the research target,builds a broadband time-domain measurement platform.Firstly,the angle measurement is carried out by transmitting a signal with a center frequency of 28 GHz and a bandwidth of 2 GHz.The receiving end uses a sampling rate of 2.4 GSample/s to achieve a multipath resolution of 0.42 ns,capturing rich multipath in the IIoT scenarios,the power angular spectrum is obtained,and the source of the received signal is deeply explored in combination with the walls,metal devices and other objects in the actual scenario.Then the channel parameters are extracted and the wireless channels under different antenna heights are compared.In addition,channels of 17 frequencies with a bandwidth of 200 MHz are measured,and typical frequencies are selected to analyze the characteristics of multipath in the power delay spectrum.The research in this thesis not only helps to understand the signal propagation mechanism in industrial Internet scenarios,but also enriches the channel measurement database of the IIoT scenarios through a large amount of measurement work.(2)Analysis and modeling of channel characteristics under different antenna heights in the IIoT scenarios.Considering the high ceiling,flexible antenna deployment position in the IIoT scenarios and the relationship between the height of the antenna and the height of the metal scatterer,two sub-scenarios where the antenna is higher than the metal scatterer and the antenna is lower than the metal scatterer are set up.The difference of the path loss model under different antenna heights in LOS propagation conditions and the additional loss caused by occlusion under different antenna heights in NLOS propagation conditions is analyzed.The distance-dependent model of delay spread is established,the lognormal distribution is fitted to delay spread,and the statistical distribution mean value of delay spread under different antenna height is compared.(3)Frequency dependency analysis and modeling of channel characteristics in the IIoT scenarios.In this thesis,the influence of other influencing factors is strictly excluded.In the measurement scenario,channel measurements at 17 signal frequencies in the frequency range of 3.3 GHz to 39 GHz are carried out.Considering the limited low-frequency bandwidth,200 MHz is selected as the signal bandwidth.Firstly,the path loss at different frequencies is extracted,and the ABG model is used for fitting the data.Secondly,according to the measurement results of delay spread,a frequency-dependent model of delay spread is proposed.Finally,the frequency dependence of the Rice factor is analyzed and modeled.