A Topology And Routing Design Of Navigation Satellite System Inter-Satellite Links

Autonomous Navigation is an inevitable trend of the future development of Global Navigation Satellite System(GNSS),and inter-satellite measurement and data transmission based on inter-satellite link is the basis for maintaining autonomous Navigation.Relying on the inter-satellite link,the satellite navigation system can not only independently carry out the ephemeris,clock difference calculation and navigation message transmission under the condition of less or no dependence on the ground station,so as to provide navigation services for users,but also solve the problem of the limitation of the regional monitoring and control network station in China.Therefore,the study of intersatellite link has become the most important task in China's beidou construction.The network design and routing planning of intersatellite link is an important link to realize the efficient operation of intersatellite link network.In this paper,based on the actual requirements of satellite-earth joint orbit determination and telemetry return service,the network strategy of satellite navigation constellation inter-satellite link and the planning of telemetry return path are preliminarily studied.The main work is as follows:1)Analysis of the working system of the intersatellite link in the navigation constellation.First,the MEO constellation containing walker24/3/1 and the mixed constellation model with 3 GEO and 3 IGSO were determined.Secondly,considering the existing equipment technology and complex space environment,the frequency-used inter-satellite signal is discussed and analyzed,and the ka-frequency band is determined to be used to construct the inter-satellite link.Correspondingly,the antenna is 1Ka phased array antenna.Then,combined with the high dynamic characteristics of the intersatellite link network,high measurement accuracy and weak interference requirements,the communication system combining time division multiple access and space division multiple access is determined.Finally,the establishment condition of inter-satellite link is given.2)Visibility analysis of all network nodes and analysis of time slot planning algorithm.For satellite constellation complex topology structure and the star point of the link between communication system of the beam,with rail,detournement tree and tree layer was studied between the visual relationship between different types of satellite,on this basis,draw lessons from the thought of finite state automata(FSA),link between specification star chain cycle of building,avoid the frequent change of topological structure impact on the stability of the system.The design method of non-permanent link based on GDOP contribution value is proposed,which breaks through the technical problem of low positioning accuracy caused by the single satellite link.The average PDOP<2.2 of any MEO orbit determination accuracy is achieved.Thus,the service quality of global navigation system is improved.3)Routing algorithm analysis.For high dynamic link between,the timing of the star,the advantages and disadvantages of traditional routing algorithms are analyzed and the suitable scene,this paper proposes A routing algorithm based on time-varying graph model of A* search,break through the temporal change built chain brought about by the high waiting delay switch,high dynamic topology routing reconstruction problem,implements the entire network satellite telemetry data distributed to the technical index of the average delay is better than 1 min,so as to improve the network transmission performance of navigation system.