Mobility Management Technology For Low Orbit Constellation

The low-orbit satellite network can achieve global coverage,provide global personal communication services,and complement and extend the terrestrial cellular mobile communication system.In the construction of constellation systems,the traditional low-orbit constellation has been rapidly updated,and the emerging low-orbit constellation has steadily advanced deployment,which has jointly promoted the development of low-orbit satellite network construction.Mobility management technology is one of the key technologies for satellite network communication.Due to the characteristics of satellite network,such as high dynamics and topological changes,the construction of an efficient mobility management mechanism suitable for low-orbit satellite network faces many challenges.This paper studies the characteristics of satellite networks and the problems highlighted by applying the existing ground mobility management mechanisms.The specific work is as follows:In view of the high dynamic characteristics of low-orbit satellite networks,the frequent passive handover of users leads to the problems of heavy mobility management load and large handover delay.To solve these problems,a low-orbit satellite network mobility management mechanism based on virtual agent domain is proposed.This paper builds a virtualized mobility management mechanism based on the MIPv6 protocol,namely the virtual mobile IPv6 protocol.Virtualization focuses on the setting of logical concepts.In this mechanism,for the problems that the resources are strictly limited and the ground station is difficult to deploy,a virtual agent cluster(VAC)is designed to co-manage the network architecture of users in the corresponding virtual agent domain(VAD).Utilizing on-board processing and switching capabilities,the architecture of distributed mobility management mechanism is adopted to support information sharing in virtual agent clusters,reduce the performance requirements for single satellites,and improve system scalability.In addition,in the low-orbit satellite constellation system,the network topology changes dynamically,and the high-speed moving satellite makes the user often passively move.Frequent switching results in a significant increase in signaling overhead for the mobility management protocol.At the same time,the long delay link characteristics in the network also lead to an increase in handover delay.For the problems of heavy mobility management load and large handover delay,we construct the home mobile-agent-anchor(HMAA)and the local MAA.In this way,the MN triggers a binding update to the HA only when the home MAA is lost,and the MN's switching within the VAD only needs to update its intra-domain relations,which reduces the overhead of mobility management and switching delay.The mechanism can optimize the flow of the mobility management protocol,adapt to the high dynamic characteristics of the low-orbit satellite network,reduce the requirements on the number of ground stations,and improve the performance of mobility management.In the given scenario,the mobility management overhead of this mechanism is only 64% of that of mobile IPv6 protocol.Finally,this paper designs and implements a low-orbit satellite network mobility management simulation platform,which consists of three subsystems: topology management,mobility management protocol implementation,and performance evaluation and display.The simulation platform combines the new mobility management mechanism proposed in this paper to realize the low-orbit satellite network mobility management protocol based on virtual agent domain.In the test simulation environment,the platform implements functional testing,protocol workflow testing,and statistics of protocol operational data,verifying the availability and efficiency of the protocol.