Research On Routing Strategy For Large Scale Satellite Constellation With Low Earth Orbit

With the growing need for network service,satellite communication system attracts many people.The extensive coverage,long distance communication capability and no limitation on nature and geography conditions are three major features of such systems,which bring in many advantages such as mobile communication ability and faster network construction.Meanwhile,comparing with Medium Earth Orbit and Geostationary Earth Orbit satellite communication systems,Low Earth Orbit satellite communication systems have the advantages of low delay,low power consumption and extensive coverage.OneWeb system is a new LEO system.Different from Iridium system,globalstar system,the major features of OneWeb system can be summarized into two aspects: The number of satellites is large and no inter-satellite links exist between satellites.Therefore it is significant to do some research on the routing problems on such systems.As mentioned before,this thesis first introduces the background knowledge of the existing routing algorithms and analyzes the reason why they can't be directly applied into OneWeb systems.Then we build a model of OneWeb systems with Matlab.Through the construction of main incidence matrix between the satellites and the ground stations,we apply the shortest path selection algorithm and demonstrate the correctness of such method.Moreover,we modify the traditional algorithm by eliminating the irrelevant satellites in the system,which simplify the matrix and reduce the time and space complexity.In addition,we discuss the influence on the number of ground stations and analyze the transmission delay.Extensive simulation results present the relationship between the number of stations and delay.Finally,the interference between different satellites systems are also investigated in this thesis.We consider MEO satellite systems and further modify the routing algorithm based on the sub-satellite point distance and intersection angle between satellites and prove the effectiveness through simulations.The results show that the immunity from interference improves with little sacrifice on the transmission delay through our mechanisms.