Research On Routing Technology Of LEO Satellite Network

Self-organizing LEO satellite network has the advantages of low delay,strong invulnerability and flexibility and is the core element of space-based integrated information network.LEO satellite network includes many kinds of network structures,such as constellation,star cluster and formation,with large span of time-space scale of link,dynamic change of topology and prolongation of network reconfiguration,which results in serious packet loss and delay in data transmission.On the other hand,the communication environment is more open and the satellite is vulnerable to attack,so the security routing between satellites becomes a key problem.Specific research findings and contributions are summarized as follows: LEO satellite network can transmit remote sensing data in real time,which plays an important role in military communication and emergency rescue.In this paper,the path establishment mechanism of data transmission is studied,which mainly solves the problem of transmission interruption caused by the change of cooperative satellite(currently visible to the earth station).And the routing metric of path persistent service time is proposed to measure the transmission time of the path supporting,and to determine the optimal path with the goal of maximum path persistent service time.Based on the predictability of the orbit,inherited cooperative satellite(the next satellite that is visible to the earth station)is introduced.When the cooperative satellite deviates from the earth station,the path is interrupted.When the path contains the inherited cooperative satellite,the inherited cooperative satellite can continue to transmit data,the transmission process is not interrupted,and the path reconstruction is avoided.The simulation platform of LEO satellite network is built based on NS3.The network includes LEO constellation and formation,and the satellite can establish the inter-satellite link independently.The proposed routing protocol is used to transmit the data to cooperative satellite and compared with the traditional routing protocol to verify its effectiveness in satellite data transmission.Considering the potential routing attacks in satellite network,such as the gray hole attack of malicious discard data and the interrupt routing attack that destroys the routing process,a measure of node security estimation is designed,which is based on the characteristics of satellite network.The metric is service-oriented,considering data forwarding familiarity,response delay,routing interrupt,routing connectivity and link on-off frequency are considered.Due to the influence of network state,legal nodes may exhibit anomalies.A dynamic adjustment mechanism for evaluating weight factor is proposed,in which malicious nodes and legitimate nodes with abnormal behavior can be identified when the network state is more congested.On this basis,the inter-satellite multipath routing protocol is designed.According to the hops,the evaluation level of network state and the result of security evaluation,several paths with low probability of attack are established to improve the reliability of data transmission.In the LEO satellite network simulation platform,malicious nodes are set up and the proposed routing protocol is simulated to verify its security performance in data transmission.