Research On Mobility Support Of LEO Satellite Network

With the rapid development of Spatial Information technology,the construction of Satellite Internet has become a national strategy.LEO satellite has many advantages in communicating with the ground terminals.global coverage.LEO satellite can provide Internet services to users all over the world with low transmission delay,low power consumption link and strong damage resistance.LEO satellite improves the communication ability with small mobile terminals which is exactly needed in the Satellite Internet construction.However,the low orbit satellite moves at a high speed relative to the ground,and the viewing time of the ground terminal to one satellite is usually only a few minutes.Ground termianls have to switch between satellites.Therefore,it is of profound practical significance to support mobility from the characteristics of LEO satellite network.A reasonable and effective mobility management scheme is needed to reduce the switching time delay and the management cost and prevent the loss of data.The specific work is as follows:With the consideration of LEO satellite network's predictive satellite-satellite topology and complex space-ground topology,a satellite network architecture based on routing separation from mobility is proposed to solve the problems raised above.The system is divided into routing module and mobility management module.Mobility management module is responsible for acquiring the service satellite of destination terminal.Meanwhile routing module is responsible for switching data to destination satellite according to routing table.Adopting the management idea of MIPv4 and MIPv6,we implement mobility management on this LEO satellite network architecture.Through theoretical analysis and simulation analysis,the architecture is proved right.At the same time,MIP protocol applied to the satellite network directly showed many problems such as high switching frequency and longer registration time delay in LEO satellite network than in the ground network.All of the above cause registered cost and switch delay time increase.To solve the problems existing in the mobile IP protocol,a mobility management scheme based on dynamic service domain is proposed using static ground location partition to manage termianls' location.Location registration is performed only when the terminal leaves the ground location area.At the same time,in order to shield the influence of the link layer access control strategy,this paper selects the ground location division to form the service domain according to certain rules.The terminal information is shared between the corresponding satellites of the service domain to ensure that the access satellite of the terminal is included in the corresponding satellites of the service domain.When the data packet is outside the destination service domain,it will be forwarded to the corresponding satellite in the service domain center;when the data reaches the edge of the destination service domain,it will query the terminal information stored and forward the data to the access satellite of the terminal.Through theoretical analysis,the scheme does reduce the registration cost of the MIP scheme and increases the maintenance cost of the service domain is proved.At the same time,applicable conditions for the construction of the service domain are given.Finally,the simulation implementation and simulation analysis of the mobility management scheme based on the dynamic service domain are introduced.And then the simulation software STK and OPNET and the modeling methods of mobility management solutions are introduced.Through network layer,node layer and process layer modeling,the mechanism and process of the solution is fully realized.Finally,the performance of decoupling of network layer and link layer mobility management and the overall performance were simulated and analyzed to verify the feasibility and effectiveness of the scheme.