Spatial Information Network Optimization And Performance Simulation

With the development of aerospace technology,spatial information network technology has been widely used in military and civil aspects.The spatial information network has the characteristics of extensive coverage,flexible access to mobile and so on.It has a good complementary relationship with the ground network.In the spatial information network,satellite nodes have high-speed mobility and periodicity,which leads to frequent link switching of the network.At the same time,the space link has a high bit error rate,a long transmission delay,and limited network resources.The unique space communication environment makes the existing network protocols and routing methods unable to guarantee quality of service.Due to the nonhomogeneous traffic distribution of users,the traffic load of satellite nodes tend to be very different.The importance of different nodes in the communication process is also different.The spatial environment of the spatial information network is relatively harsh.The satellite node's position information is relatively open,and it is vulnerable to the influence of the natural environment and human damage.Therefore,spatial information networks need to have strong resistance to destruction.The current spatial information networks are mostly studied from the perspective of the transmission performance of routing algorithms.There is less research on the importance and invulnerability of nodes.In this thesis,the routing technology in spatial information network,the importance of nodes in communication process,and the survivability of space information network are studied.It includes the following parts:(1)In order to build the global spatial information network,a double-layer satellite network model of 3GEO+66LEO is built,and visibility analysis is carried out for the nodes of different layers in the spatial information network.(2)The Qos routing algorithm of satellite network is improved.The algorithm reduces the influence of node mobility on network routing by using virtual topology,and adopts different routing strategies in different heights of satellite networks.The algorithm mainly improves the following three aspects:1The least hop routing algorithm in GEO layer is optimized,which reduces the transmission delay of high delay demand data in GEO layer.2The congestion control process is improved and a multi-node combined congestion control strategy is used.The traffic detour is carried out in the dual path transmission of the LEO layer,which improves the transmission performance of the network.3The route selection is based on the distance and the next hop node congestion.The transmission distance of the current node to the destination node is fully considered.The simulation results show that the improved routing algorithm can achieve smaller packet loss rate,and the throughput of the network has been improved to meet the requirement of various types of businesses.(3)For the problem of the nodes importance in spatial information network nodes during communication,an evaluation method for determining the importance of nodes in the transmission process is proposed.This method takes into account node dependence,the distance between nodes and other factors,and can accurately evaluate the importance of satellite nodes in satellite network communication.The method of node importance evaluation is verified by the method of node contribution.(4)In this thesis,the survivability routing technology in spatial information network is studied.The data transmission of satellite network under the scenarios of node failure and security threat is analyzed.According to different network fault types,a corresponding invulnerability routing strategy is designed.The effectiveness of the survivability routing technology is verified by simulation.