| With the rapid development of modern communication services,satellite networks have become a powerful supplement to the ground mobile network because of its advantages of high speed,wide geographical coverage and not being affected by geographical location.However,the high-speed dynamic change of satellite network operation and the large difference of user density in different areas will leads to uneven distribution of system traffic at the same time,resulting in congestion of nodes in the network,and produce higher end-to-end transmission delay and packet loss rate,which finally impact on the transmission performance of satellite networks.Therefore,it is important to design and implement the congestion-control routing simulation platform for Low Earth Orbit(LEO)satellite.Because of the rich library of network component objects and relatively perfect underlying programming modeling logic of Network Simulation version 3(NS3),it can be better to describe the congestion problem and realize the dynamic simulation system of the congestion-control routing simulation platform for LEO satellite based on NS3.However,it is challenging to design and implement the simulation platform due to the large number of network component object libraries and the complex system overall framework modeling process of NS3,and there are few detailed introductions in existing literatures.In conclusion,in order to better conduct system-level simulation research on the congestion-control routing strategy for LEO satellite,this paper designed the implementation method of the routing protocol simulation platform for LEO satellite networks based on the underlying modeling logic of NS3.This paper designed and implemented a network simulation platform for LEO satellites to realize congestion-control routing,proposed a set of design ideas and implementation methods based on the NS3 network framework.Firstly,based on the theory of the congestion-control problem of LEO satellite networks and the network framework of NS3,a network congestion-control routing protocol simulation platform plan is designed.Secondly,the system architecture is constructed according to the four levels of application layer,transmission layer,network layer and network interface layer.In the application layer,data receiving and sending applications are used to realize data receiving and sending.Different data flow transmission rates are designed in data receiving and sending applications to simulate different satellite load states and satellite congestion scenarios.The internal implementation logic of data receiving and receiving application is analyzed.In the transmission layer,Socket is used to realize the business logic of the application layer,and the realization process of the transmission layer is analyzed to undertake the application layer and transfer the network layer.In the network layer,the congestion-control routing protocol module is designed,and the implementation of congestion control routing protocol is divided into routing table establishment and load balancing module,using the shortest routing algorithm to establish the initial routing table,and the timer to test the satellite load and link-state.When it is detected that the satellite is congested or the link is broken,the backup path is used to redistribute the traffic,thus realizing the balance of the satellite traffic.In the network interface layer,a mobility model is designed to simulate the trajectory of LEO satellite,and its implementation is aggregated into the mobility model library.Finally,the simulation test and analysis of congestion-control routing protocol verify its effectiveness. |
