Modeling And Simulation Implementation For LEO Mobile Channel

Satellite communication networks are considered to be an important part of future communications by virtue of their wide coverage and flexible network formation.Among them,low-orbit satellites have become a current research hotspot due to their low orbital altitude,short communication delay and low link loss.In order to ensure reliable LEO satellite communication,it is necessary to study its channel transmission characteristics and establish a channel model.However,the high-speed movement of LEO satellites leads to continuous changes in communication elevation angle,while the satellite communication transmission environment is complex,which makes the current satellite channel model unable to accurately portray the time-varying characteristics of the channel.To solve the above problems,this paper focuses on the fading time-varying characteristics of LEO satellite channel model,and the innovative points and contributions of the paper are as follows:1.LEO satellite channel modeling and simulation for a variety of ground environment scenarios.Based on the Tapped Delay Line(TDL)channel model,this paper proposes a LEO satellite mobile channel model suitable for various scenarios such as dense urban areas,urban areas,and rural areas.When modeling,different multipath numbers and different degrees of shadow fading are adopted for different scenes and different elevation angles.At the same time,when realizing the fading factor of the low-orbit satellite channel,according to the different communication environments of the ground receiver,the classic Jakes doppler power spectrum and the bilateral truncated Jakes power spectrum are used to realize the Rayleigh fading characteristics of the channel.After analyzing the simulation results of the model,it is shown that the channel fading variation obtained by the multi-scenario LEO satellite channel model is suitable for the LEO satellite channel.2.Development of a LEO satellite channel simulation platform.In this paper,a visual graphical interface is designed to simulate the motion trajectory of satellites,and a modular LEO satellite channel model simulation platform is built.The platform not only supports the proposed multi-scenario LEO satellite channel model,but also simulates the C.Loo and Corazza narrowband channel models,The simulation platform calculates the satellite motion trajectory according to the orbital data of LEO satellite,judges the visibility with the ground receiver in real time,dynamically calculates the rainfall attenuation,atmospheric absorption attenuation,shadow fading,small-scale fading and multipath delay of the channel,and finally generates the impulse response data of the channel.The simulation platform is used to analyze the power loss change on the communication link,the number of multipath signals and the time-varying characteristics of doppler frequency shift when LEO satellite is moving.3.Multi-scenario LEO satellite channel characteristics analysis and verification.Based on the developed LEO satellite channel simulation platform,this paper analyzes the fading power of the channel in dense urban,urban and rural scenarios.The power delay at different elevation angles in urban scenes is analyzed,and the power delay spectra of direct diameter and multipath are depicted respectively,which intuitively illustrates the characteristics of low elevation angle and high delay of satellite signals.Finally,the model fading parameters in 3GPP TR38.811 are used to verify the fading of channels under two different belief angles in dense urban areas and rural scenes.The results show that the channel fading parameters obtained by LEO satellite mobile channel model proposed in this paper have a good agreement with the fading parameters in 3GPP TR38.811,which proves the accuracy of the model simulation results.In summary,based on the TDL model,this paper models and simulates the LEO satellite channel,which is suitable for a variety of ground environments and multiple belief angles,and finally builds a LEO satellite channel simulation platform,through which the verification of the multi-scenario LEO satellite channel model and channel characteristic analysis are completed,which provides reference for subsequent research.