| Low Earth Orbit(LEO)satellite network is an important part of space integrated network,which can play an important role in national defense security,ocean navigation and other application fields.Because LEO satellite network has the characteristics of large network scale,complex architecture and so on,it is necessary to strictly simulate and verify the relevant functions of LEO satellite network before the network protocol and service system are really applied to the LEO satellite network system.Therefore,how to build an easy to deploy,accurate and reliable LEO satellite network simulation environment on the ground has become the focus of researchers,which has great theoretical value and practical significance.This paper studies the key technologies of LEO satellite network simulation based on container cloud.The specific work is as follows:1.In view of the defects of the current satellite network simulation software,based on the characteristics of LEO satellite network,a new generation of LEO satellite network simulation cloud is designed and built,which maps and interfaces from the actual LEO satellite network to the container virtualization network.The simulation cloud adopts a distributed architecture and integrates the advantages of the three state Markov LEO broadband satellite channel model in accurately simulating the LEO broadband satellite channel environment,the advantages of STK software in accurately measuring the satellite orbit,the advantages of Software Defined Network(SDN)in centralized network control and the advantages of lightweight virtualization of containers.It supports the real-time simulation of large-scale satellite networks.2.Based on the channel characteristics of LEO broadband satellite mobile communication system,this paper improves the existing three state Markov satellite channel model,establishes the three state Markov LEO broadband satellite channel model,and applies it to the dynamic link simulation of LEO satellite network.In the simulation of LEO satellite network,the bit error rate of inter satellite link is mapped to the packet loss rate of virtual link between containers.The fitting degree between the satellite channel model and the actual satellite communication scenario determines the accuracy of the packet loss rate of the virtual link between containers.Most of the existing multi state Markov satellite channel models are oriented to narrow-band satellite channels,and the states are mostly described by narrow-band satellite channel models such as C.Loo and Suzuki,which cannot match the characteristics of LEO broadband satellite channel models.The three state Markov LEO broadband satellite channel model comprehensively considers the free space loss and other losses in the process of satellite transmission.Based on the Tapped Delay Line(TDL)channel model,the three state Markov process is introduced according to the shadow fading degree of the direct path.The simulation results show that the model can meet the needs of LEO satellite network simulation.3.In view of the frequent changes of LEO satellite network topology,a SDN architecture with Ryu controller as the control plane and Openv Switch(OVS)as the data forwarding layer is designed to enhance the flexibility of network flow control.At the same time,based on the development of Ryu application,the simulation cloud has the ability of time-varying network topology simulation;In view of the high accuracy of link parameter simulation of LEO satellite network,the bit error rate parameters of satellite link are obtained through the three state Markov LEO broadband satellite channel model,and the fine control of link parameters is realized based on the link simulation principle of Linux kernel.In addition,s Flow technology and Weave Scope tools are innovatively integrated into the simulation cloud to realize real-time monitoring of resources. |
