Multi Scene Doppler Power Spectrum Modeling And Hardware Implementation For LEO Satellite Channel

As an important part of the integrated information network between space and earth,low orbit satellite communication system is a hot topic in the field of new generation communication.In the low orbit satellite transmission environment,channel fading will directly affect the performance of the communication system.The real channel characteristics can be described by constructing channel model,so it can provide the precondition for system design and optimization.In the modeling of low orbit satellite channel,because of its characteristics of Doppler effect,continuous change of satellite elevation and ground receiving environment,and strong dynamic performance of multipath fading,Doppler power spectrum modeling will face the problems of low accuracy of model representation and large error of model parameter fitting.In order to solve the above problems and improve the accuracy of the model,this paper focuses on the Doppler power spectrum modeling.The innovation points and contributions of the paper are as follows:In view of the dynamic change of channel fading characteristics during transit of low orbit satellites,the Doppler power spectrum is rich and changeable,which is difficult to describe accurately by existing models.In this paper,we study and propose a bilateral truncated asymmetric Rician power spectrum model and its simulation algorithm.The model can adjust the shape of Doppler power spectrum flexibly by using a set of model parameters according to the difference between low orbit satellite and ground channel,so as to uniformly characterize the shape change characteristics of Doppler power spectrum caused by dynamic changes of multi scene during satellite transit.Aiming at the large amount of data in modeling and the easy to overlap among different scenes,which leads to the large error of model parameter fitting,this paper proposes a model parameter fitting method based on fingerprint method.This method extracts and classifies the measurement data samples of Doppler power spectrum in multiple scenes,and selects the most representative data in each scene The data can fit the model parameters,and then obtain the accurate parameters of Doppler power spectrum model in multi scene.In the suburban and urban environment with different elevation angles,RMSE between the model and the measured data based on fingerprint fitting is significantly lower than the existing fitting method,which proves that the method can eliminate the multi scene sample mixing and improve the modeling accuracy.According to the proposed Doppler power spectrum modeling method,this paper designs and implements the function module of Doppler shift and Doppler power spectrum of low orbit satellite channel simulator based on Lab VIEW platform.The performance of the realization function is verified and evaluated by building hardware verification platform.The results show that the error of Doppler shift measurement is less than 0.15%when the bandwidth is 100MHz,and the average RMSE between the Doppler power spectrum and the theoretical value and simulation based on sum of sinusoids(SOS)algorithm is 0.15 and 0.18 respectively when the number of sinusoids used is 48.Therefore,the Doppler power spectrum model implemented in this paper is more accurate.