Design And Implementation Of Dynamic Doppler Frequency Extension For Wireless Channel Emulato

With the acceleration of the commercialization of 5G technology,the application scenarios of wireless communication continue to expand,and people’s requirements for wireless communication systems are gradually increasing.In the planning and development of wireless communication systems,the cost of choosing to conduct experiments in the actual transmission environment is too high.The wireless channel simulator can simulate the transmission characteristics of wireless signals in a near-real propagation environment,which is used for testing in the development process of wireless communication systems,which can significantly reduce development costs.However,the existing wireless channel emulator shows many shortcomings in simulation speed and resource occupation,and it is difficult to meet the dynamic channel simulation.The research content for simulators includes channel modeling,dynamic simulation and hardware implementation:(1)In order to solve the problem that the existing simulation model needs multiple simulations to obtain a better Doppler power spectrum,after analyzing the modeling schemes of existing models,a time-varying parameter channel model is proposed,which increases the number of random angles of arrival changes during simulation,so that the Doppler frequency shift of the channel is more,and then the Doppler frequency extension and Doppler power spectrum with good effect are obtained.The simulation results show that the time-varying parameter model successfully solve the efficiency problem that requires multiple simulations while retaining the advantages of the proposed models,and are suitable for implementation on the Field Programmable Gate Array(FPGA).(2)Aiming at the problem that it is difficult to implement dynamic simulation of channels on FPGA,a method for adjusting the interpolation factor to implement the dynamic change of channel Doppler extension is proposed,which implements the adjustment of the bandwidth of the channel coefficient by interpolating the channel coefficient in the time domain.The simulation results show that the method can use the static channel coefficient obtained in a single simulation to simulate the dynamic channel of various situations.(3)In order to further implement the time-varying parameter channel model and dynamic channel simulation,these two parts are implemented based on FPGA to obtain the dynamic Doppler frequency extension module.After testing and verifying the dynamic Doppler extension module and its various units,it is proved that the module can simulate the Doppler power spectrum and Doppler extension with better effect in a single time,and can change the two according to the change of channel environment.