The Networking Method And Performance Evaluation For Large-scale LEO Satellite

With the continuous development of satellite communication technology,it is possible to integrate satellite network into ground communication network.Although the ground network is developing rapidly,it cannot cope with sudden natural disasters.Due to the cost problem,people in remote areas may not have the Internet access.For users in the above areas,satellite access is an important choice.For the rapid development of the network demand of ground users,space satellite network with wide coverage and high bandwidth can provide a great buffer solution.The satellite network is an indispensable part.in the future network construction.Among all kinds of satellites,LEO has the advantages of small ground height,less propagation delay and small signal attenuation.At the same time,as the first level for users to access the space-based network,considering the satellite power and launch management cost,LEO may be the most ideal satellite access mode for ground users.However,due to the frequent changes of satellite topology and the large scale of constellation,the traditional ground routing protocol cannot be directly applied to LEO satellite network.Therefore,we need a more reasonable method to realize the routing management of space satellite segment.Taking large-scale LEO satellite constellation as an example,this thesis explores the methods and Strategies of satellite level networking.The main contents in the thesis are summarized as follows:1.In this thesis,we use STK and other tools to build the Walker Constellation scene of LEO satellite,and simulate their geometric characteristics.After verification and inference,we finally adopt the connection scheme that each satellite has four inter satellite links.We propose a distributed routing scheme based on lateral link length,which quantifies the topology changes of large-scale LEO satellites.The satellite address is set,and the forwarding direction of distributed data is determined according to the relative position of the source node and the target node.Combined with the change of link length between adjacent satellites,the next hop forwarding of data is determined.Compared with the common satellite routing algorithm,this method saves the computing cost and routing storage resources.2.An active congestion management strategy is proposed.Due to the particularity of constellation structure,in a transmission scenario,the data can be easily concentrated on a satellite node.We set a fixed time slot between adjacent satellite nodes to exchange their own cache.Based on the above routing method,packets will bypass some key links with a certain probability to avoid congestion.3.A distributed fault management strategy is proposed,which makes full use of the connection characteristics of LEO satellite constellation.When a satellite fails,it only needs to announce the location of the faulty node between satellites,and signaling exchange can be completed within the limited fault area.Compared with the centralized fault management strategy,this method has less signaling overhead and better convergence.