Research On Multi-layer Satellite Network Modeling And Fault Diagnosis Technology

Satellites are the most frequently launched and most versatile spacecraft at present.With the increase of communication demands,it is difficult for a single satellite to handle the increasing volume of business.The networking technology of multi-layer satellite network composed of multiple satellites arises at the historic moment.However,because satellites are in outer space,the environment is harsh,and the orbit information is easy to detect.Besides faults caused by natural factors and their own factors,satellites are vulnerable to deliberate attacks.Therefore,it is necessary to describe the attack and defense process and study the faults caused by attacks.The early warning satellite is an important application of satellites in the military field.Its typical representative is space-based infrared system(SBIRS),which has important research value as a multi-layer satellite network.This paper takes SBIRS as the research object,and conducts research on the establishment of its simulation model,the description of attacking and defensing process,and fault diagnosis,including the following:(1)Build SBIRS simulation model using STK and OPNET software.Through the generation function of satellite orbit provided by STK,the required orbit files and the visibility of data between satellites are formed.In OPNET,the models of GEO,HEO,LEO and ground nodes are built respectively.The processor module and queue module are used to simulate the satellite communication process,including the creation,sending,queuing,receiving and destruction of data packet.In the radio receiver and transmitter module of the node,setting functions simulate various characteristics of the wireless link.And the packet model is established to simulate the data transmission.Finally,a multi-layer satellite network model of 4GEO + 2HEO + 24 LEO is formed.(2)Using the knowledge of game theory,the attack and defense process of the early warning satellite system is constructed as a static game model.First,the weakness of satellites and possible attacks on them are described.Then,in the case of complete information and incomplete information,the strategies that both sides should adopt are analyzed.The obtained capacity data by simulations is used to characterize the failure probability of the node under attack.The attack and defense strategies based on the simulation data are proposed.Finally,the optimization of the model under incomplete information is analyzed based on the simulation data.(3)A dynamic game model is established to describe the whole attack and defense process,including alternate attacks and defensive counterattacks of two sides,which is characterized as three stages.A possible attack and defense process is introduced in detail through analyzing the benefits.Quantify the costs of both parties,the conditions of stopping attacks or counterattacks are given based on the ratio of network delay and cost obtained by simulations.(4)On the basis of the attack and defense model,the simulation is operated by the data monitored by ground stations and data packets received from the satellite.The failures resulting from attacks on satellite nodes have a significant impact on the network based on the analysis of these data.The judgment method is given according to the model and the simulation is used to verify the effectiveness of the judgment method.