Study On Optimization And Invulnerability Of The Space Information Network

With the development of communication network technology and aerospace technology,traditional ground network cannot meet the growing human rapid access to information and data transmission demand.The space information network has a large coverage,high bandwidth and high service,which can better meet the needs of human communication.The satellite network works as the backbone of the communication system,whose performance affects the whole performance of space information network.How to further improve the performance of the satellite network is a key problem and the routing problem is one of the most important issues.The reason is that every node in the network is constantly changing over time and that communication links between the nodes shows the phenomenon of intermittent connectivity,which leads to the time-varying topology in satellite networks.The key to planning a superior routing scheme is how to deal with and optimize the time-varying topology of the system.Based on the predictability of satellite network nodes and links,the topology and routing problems of satellite networks are deeply analyzed,and the corresponding solutions are given.(1)According to different classification standards,the existing classical routing schemes are summarized and classified,and the main principles,core mechanisms,application scope,advantages and disadvantages of these routing schemes are discussed.(2)Considering the advantages of the low orbit and geostationary node network,one double-layer network model with excellent performance can be established.Based on this topology model,the coverage area of any low orbit node in the network is replaced by a virtual node,and the influence of the polar boundary on the footprint division of the satellite is taken into account.In addition,this model also combines the virtual topology method and the management scheme of satellite grouping,which effectively overcomes the difficulty of routing design of satellite network topology.Numerical simulations and theoretical derivation show the effectiveness of the scheme.The network topology model outperforms other network models in terms of number,average length and uniformity of time slice.(3)A useful routing scheme is designed using two-layer network.According to the network controlled by topology,the time-varying topology of the network can be,clearly,effectively controlled.Based on this,the routing frame is designed.In this routing scheme,the upper satellites can regularly obtain the topology and delay information of the lower satellite,and then can compute routing for the lower satellite while the lower satellites are responsible for the packet forwarding.The performance of data transmission is improved through the exchange of information and routing data between two kinds of satellites.The effectiveness of the related scheme is illustrated by the way of simulation.(4)A routing method using congestion avoidance is suggested.First,the routing is preestimated according to the topology characteristics of the low orbit network.Then,according to the traffic distribution in the network,the path selected can be adjusted to reduce the network congestion.In addition,in order to meet the needs of different business delay,packets are classified.Delay sensitive data packets are transmitted in real time in the network,while other packets may be forwarded with the help of the upper nodes.The congestion avoidance and packet classification mechanism could improve the network performance,and the relevant numerical simulation confirmed this fact.