Leo Satellite Communication System Switching To Management Studies

The satellite mobile communication can realize the radio communication between the mobile terminals by using the satellite repeaters which act as relay. Among the satellite mobile communication systems, the LEO-MSSs (Low Earth Orbit Mobile Satellite Systems) show the wide development space due to their global seamless coverage, much shorter transmission delays, less power requirement for the user terminals and strong ability in anti-ruin. Moreover, it will play an important role in the future personal communication system (PCS).Because of the relative high speed movement between the LEO satellites and the terrestrial user terminals, the very high handover rate during a call's lifetime, including inter-spotbeam handover in a satellite within an earth gateway centre , inter-satellite handover within an earth gateway center,inter-spotbeam handover in a satellite between earth gateway centers, and inter-satellite handover between earth gateway centers, will occur.The handover management belongs to the mobile management (MM) category. Mobile management is a time-variable mapping between mobile nodes and their addresses (node's relative network architecture position), and it is a kind of basic technology which supports the roaming-user who arrives at a new service area to accept the service. Mobile management includes two aspects: location management and handover management. Generally speaking, location management processes the inquiring and memory of the user-database as well as the transmission of paging signal, while the handover management maintains the connectivity during the movement by controlling the change of access points.In this paper, the handover in LEO-MSS is introduced and discussed deeply, and a particular handover management strategy of the low earth orbit satellite communication system which is suitable for our country is introduced. This strategy is suitable for one situation that the satellites'function in this system is a repeater without links between satellites, and the earth gateway center is defined as the control center. In this strategy, the four kinds of handover situations in LEO-MSS are processed into two situations: handover within an earth gateway center, handover between earth gateway centers. This paper has separately defined the concrete flow for the two situations, the signaling forms while executing handover, and the principle of selecting destination satellite for both high-speed users and low-speed users.At last, the network models of low earth orbit satellite communication system are builded through the OPNET network simulation software in this paper. Base on these simulation models, the handover management strategy is implemented and the simulation results are collected. The results show that the strategy this paper puts forward is feasible and effective, and these results also can provide reference for a practical network design.