| With the rapid development of satellite communication networks and the growing maturity of aerospace manufacturing technology,the satellite network architecture is developing in the direction of large-scale,multi-access,and high reliability.However,due to the high cost,short life cycle and poor maintainability of satellites,the actual satellite-ground communication test process is greatly limited.Most of the current mainstream satellite network simulation software cannot meet the requirements of both visualization and multiprotocol programming functions,and there are problems such as insufficient scalability and inconvenient data interaction.In addition,the wide coverage of satellites and the characteristics of wireless transmission make them have natural advantages in the application of multicast technology.How to realize long-distance,low-latency,multi-level multicast data transmission under limited and valuable satellite resources is an important issue.huge challenge.Therefore,it is urgent to develop a satellite simulation technology for large-scale constellations,multi-protocol support,and efficient allocation of on-board resources,and to design a reliable satellite multicast algorithm.Facing the above requirements,this paper mainly completed the following two research works:(1)At present,network simulation tools mainly implement various algorithms of communication protocols,and use different programming languages to complete existing or customized communication protocols.Their functions in network programming are superior,but they cannot fully visualize the communication process,and they also lack the corresponding simulation analysis function library for satellite orbits.Aerospace satellite analysis tools are mainly used to study the operation rules of satellites,analyze the construction and connectivity of constellation models,and the target object analysis and modeling library is rich and accurate,but cannot achieve specific satellite network protocol settings.The high-orbit constellation simulation platform designed in this paper combines the advantages of these two types of software and makes up for their respective shortcomings.The hierarchical modeling method is used to realize the multi-layer protocol algorithm,the communication process is designed to realize the efficient allocation of satellite resources,the multi-level addressing scheme is designed to realize the inter-satellite roaming of mobile users,and the satellite-ground link transmission model is constructed to simulate various environmental interference factors.The interactive simulation function is realized by the main control software of the simulation system,and the feasibility of the platform is verified by creating multiple simulation scenarios.(2)In the multicast scenario,high-orbit satellites can greatly reduce the number of onsatellite hops and reduce the inter-satellite link overhead,but at the same time,it also brings the defects of poor delay performance and high packet loss rate.The satellite-to-ground link propagation delay of low-orbit satellites is very short,which is very beneficial for applications with high real-time requirements,but low-orbit satellites require frequent switching behavior of inter-satellite links,which is easy to cause transmission signals.of instability.In addition,in a multicast scenario,if the size of group members increases,the number of intermediate and low-orbit satellites required continues to increase,the number of redundant links increases,and the link occupancy rate increases,which will occupy a large amount of on-board resources.The low-orbit constellation-assisted multicast algorithm designed in this paper combines the characteristics of high-orbit satellites and low-orbit satellites to reduce the link overhead as much as possible while shortening the propagation delay.Finally,the multicast delay and multicast success rate are tested by simulation.And the cost of multicast tree,it solves the problem of cooperative multicast under the high and low orbit constellation model. |
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